How to Plant and Care for a Shade Tree
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Today’s podcast interview focuses on consulting arborists and how they help property owners evaluate tree health. Gordon Mann explains that a consulting arborist provides independent inspections, identifies problems such as leaning, branch breakage, bark shedding, root issues, and recommends options for treatment or mitigation rather than only suggesting removal or trimming.
But we talked about a lot more regarding shade trees. Among the topics discussed:
* Call a consulting arborist (not a tree-care salesperson) every few years for an independent inspection, especially if you notice leaning, breaking branches, or unusual bark shedding. Find one via treesaregood.com [https://www.treesaregood.org] (ISA) or asca-consultants.org. [https://www.asca-consultants.org/?]
* Don’t over-water lawns and starve trees: if you cut lawn irrigation, add dedicated deep watering for trees instead (e.g., a spiral soaker hose or concentric drip rings under mulch) so roots don’t rely on turf runoff.
* Water deeply and infrequently (weekly to bi-weekly in dry season), covering the entire root zone from trunk to drip line, not just one emitter at the trunk.
* Mulch with wood chips or leaf litter (”duff”), replenished every few years, as a top dressing only, never buried under the tree. It moderates soil temperature/moisture, builds soil biology, and softens rain impact.
* Before planting, remove the tree from its container and check for circling roots; prune or score the root ball on four sides (and the bottom) to redirect root growth.
* Use the “pedestal method”: dig the planting hole to the height of the root ball (or 1 inch less), keep that pedestal of native, unexcavated soil undisturbed, but loosen a much wider area around it (2–5x the root ball diameter).
* Plant slightly high - top of the root ball about 1 inch above grade - to account for settling, and never plant in compost or heavily amended soil that will settle and bury the trunk.
* If amending soil, mix in only 8–10% organic matter across the whole dug area rather than replacing native soil entirely.
* Space trees for mature canopy size, not instant privacy. Plant further from fences and from each other to avoid crowding, root conflicts, and future removals.
* Plant a diverse mix of species (no more than two of the same species in a row) to avoid catastrophic losses from pests/disease like Dutch elm disease or emerald ash borer; include some native trees for a stronger ecological palette.
* Learn correct pruning cuts: avoid “heading cuts” (topping/chopping), which cause weak, densely packed regrowth; favor selective, purposeful cuts instead.
* Prune only for a specific reason (health, structural safety, or clearance needs). Remove no more than 5–20% of foliage annually, and retire the outdated idea of “thinning” a tree just for looks.
* For dead, dying, diseased, or crossing branches, evaluate each case individually rather than removing wholesale. A partial dead branch can sometimes be left for habitat.
* Choose the right tree for the right purpose and location up front, accounting for underground utilities and infrastructure, since trees take 15–20+ years to deliver full shade/canopy benefits.
* Give young trees a light shake 12–30 inches above the ground; if the root ball shifts, the tree isn’t rooting well and needs root pruning, transplanting, or replanting.
Today’s conversation with Consulting Arborist Gordon Mann reminded me of two of the 11 Farmer Fred Garden Rules [https://open.substack.com/pub/gardenbasics/p/11-garden-tips-for-success?r=2lhdw&utm_campaign=post-expanded-share&utm_medium=web]:
7. EVERYTHING YOU KNOW IS WRONG. In the 1940’s & 50’s, DDT was available to home gardeners as a pesticide. Turns out, it caused cancer and killed birds. In the 1960’s-70’s, the Modesto Ash was considered the “perfect shade tree” for the Central Valley of California. Turns out, it is susceptible to anthracnose, mistletoe and is no longer recommended. In the first decade of the 21st century, the pesticides Diazinon and Dursban were taken off store shelves. Also proven ineffective, despite claims to the contrary: Vitamin B-1 for transplant shock, store-bought ladybugs, and tomato calcium spray to cure blossom end rot. In horticulture, research is always ongoing.
8. IF IT WORKS FOR YOU, FINE; BUT KEEP AN OPEN MIND. If you’re using safe gardening techniques that others frown upon - and those techniques are working…well, who are we to tell you to stop? Still, new research, techniques or equipment may make your chores a heck of a lot easier and satisfying. Today’s solution could become tomorrow’s problem. Be open to change.
Even if you listened to the podcast, read the transcript. Gordon Mann had so many profound ideas about trees and tree care, you’ll learn a lot more with another read (or listen). Plus, links mentioned in the podcast for more information about trees and tree organizations can be found in the transcript.
PODCAST TRANSCRIPT:
HOW TO PLANT AND CARE FOR A SHADE TREE
Farmer Fred: Do you have trees on your property? Well, trees are usually the largest and longest live natural features on your property. Plus, they’re worth a lot of money when you go to sell your home. So it pays to take care of the trees on your property. But do you know how? Well, if you don’t know how, that might be the time to call in a consulting arborist, especially if you think that there’s going to be problems if you see the tree leaning or maybe branches are starting to break or there is some unusual shedding of bark or something like that, you want to call in a consulting arborist. Well, what is a consulting arborist? Well, let’s check in with Gordon Mann. He happens to be a consulting arborist and he has a company called Mann-Made Resources [https://mannandtrees.com] serving Northern California for residences, businesses, agencies. He’s been doing it for more than three decades and he wants your trees to succeed. But the only way those trees can succeed is if you do the right thing and treat them right. And as I’ve been saying on this program for how many years now, it’s all about the soil. And that’s so true when it comes with trees as well. Gordon, a pleasure talking with you. And I hope we can shed some light for people to help them take better care of their trees.
Gordon Mann: Thank you, Fred. I appreciate the opportunity to share some information with you. And actually, I’ve been doing this for about 45 years. And seven years ago, Handmade Resources shifted our consulting to California Tree and Landscape Consulting, CalTLC. And that’s where the consulting comes from. I also, in July, started the Institute for Soil Genomics for Healthy Community Forests. And the idea is to help people learn how to get our soils back to their natural form.
Farmer Fred: And I bet right now people are wondering, well, wait a minute, what is a consulting arborist? So why don’t you explain the difference between a regular arborist and a consulting arborist?
Gordon Mann: A consulting arborist should be someone with enough experience to come out and make an inspection on the property or the trees and figure out what any of the issues are that are, impacting the tree health or the tree condition. Usually, the consulting arborist is not part of a tree care company because most tree care salespeople show up to your property to sell tree work. There are several of them that will give some consulting out, but their job is to sell tree care. Otherwise, the company goes out of business. Nobody can just keep giving free information and stay in business for their careers. So we do charge for our independent, unbiased inspections of the trees. And the most scientific ways to help the trees grow and stay healthy. Or if the trees have some issues, how to treat the issues. And instead of just saying the trees have to be trimmed or have to be removed, we give options and mitigation options for any issues on the property.
Farmer Fred: And just like you would visit a doctor regularly or a dentist regularly, if you have trees on your property, and especially if they’re full-grown trees that could be worth thousands of dollars when the time comes to sell your property, you might want to call in a consulting arborist every few years to just do a general survey of your urban forest.
Gordon Mann: I agree with you. And I’m not just trying to sell our work. But any asset that we have requires some kind of preventative maintenance or regular maintenance. We think about all the things in our homes and our cars, and we do things to take care of them. No one drives their car until the engine seizes because they never change the oil. And trees being a very valuable asset to our property and part of the community canopy are very important and do need to be inspected occasionally and help the property owners learn how to manage their trees, structure, and health in an appropriate manner.
Farmer Fred: And to find a consulting arborist near you, there are a couple of good resources out there that can help you pinpoint somebody locally who can help you out. I know there’s the International Society of Arboriculture with their website, treesaregood.com [https://www.treesaregood.org], where you can find a list of arborists and consulting arborists. But also there’s one specifically for consulting arborists, the American Society of Consulting Arborists [https://www.asca-consultants.org].
Gordon Mann: Both of those have arborists that are either certified or with ASCA registered consulting arborists that can help you inspect the site and give you the information you need to take better care of your trees. And hopefully the person that comes out is talking to you about growing better trees and keeping your trees healthy. And helping him understand what we can do to avoid unplanned failures as much as possible. None of us are able to look completely below the ground, but we can look at differences in the site conditions, the tree trunks, and sometimes the roots. And what we normally do is we make as much assessment as we can from what we can visually see from the ground. And then if we come up with some things that we need more information on, There’s called advanced assessments, where people might go up in the air and climb the tree to do an aerial inspection and look at what’s up in the branches close up or actually excavate the soil so, those of us without x-ray vision can actually see the roots. Also, we have things we can do like tomography [tomography%20of%20trees] or resistance drilling and find out what level of decay is in trunks that might have no apparent openings that we can see inside but sound hollow and we use a mallet to check the quality of the wood.
Farmer Fred: The American Society of Consulting Arborists, their website is asca-consultants.org. And it will have a link to both the American Society of Consulting Arborists and the International Society of Arboriculture [https://www.treesaregood.org] in today’s show notes as well. I know you’ve been going around giving presentations on tree health, and I’m amazed at the resiliency of trees, how even though to the naked eye they might appear to be healthy, they could be stressed because they were started poorly, and not the least of which is when they may have been planted when the housing development you live in was finally developed. Usually the landscape goes in as the very last thing after all the construction work, and that initial landscape is being installed on compacted soil and maybe very little topsoil just because of the construction process.
Gordon Mann: Yes, Fred. It’s really sad how when we look at the difference in how trees have grown in our communities from 50 years ago to current, they used to build individual houses. They didn’t scrape the entire site, all the topsoil off and compact it so they can build the houses so they don’t settle. And then they come in with four inches of topsoil and try and get the trees to grow. I hope some of your listeners have actually had the opportunity to walk into wildland areas or forests. We have so many national forests in our area and county forests and things like that where we can actually see how trees grow naturally. And hopefully they walk across a duff layer that It is a tree’s natural fertilizer, a natural way to restore the soils, with the elements that it needs to function properly. So soils and soil genomics are very like the human gut. There’s so much more information now about the biomes and things going on in the human gut that help our bodies care for themselves. The soils are the exact same way. And there’s so many fungi and bacteria in the soil that help promote earthworms and other things that are happening in the soil that sometimes you need a microscope to look at. And when we scrape the organic matter off the top of the soil and we compact it, then it eliminates a lot of how those organisms can grow. It changes the soil porosity and permeability. It changes the soil aeration. And most people just think that tree roots need water, but roots need both air and water because they’re living cells and cells need oxygen. And most of the microbiomes in the soil are not anaerobic, so they also need oxygen and air. And so what we try to do at the institute is we do actual soil tests.
Not the normal one that goes through the local cooperative extension agencies and some of the soil testing we do that just talks about the elements in fertilizer, nitrogen, phosphorus, and potassium, and pH. But we actually look at up to 120,000 microorganisms, both bacteria and fungi, and what’s missing. And it looks at what nutrients that are actually tied up in the soil and unavailable to the plant because the bacteria and fungi that help the roots extracted from the soil are damaged or missing. And the other thing humans do really well is we clean our soil. We rake in all the organic matter and all the leaves and any loose organic material off the soil.
And it does two things. It protects the soil from the sun so what we have otherwise is baked soil that’s kind of like a brick so anytime we get water it usually runs off until the soil gets so saturated that it finally does soak in a little bit or, it does just run off and it never goes deep into the soil. And because the soil is baked, the organic matter and the fungi and bacteria that are in the shallow areas of the soil that normally replenish the soil, are actually either killed or lost. And we have very poor quality soils.
Farmer Fred: Earlier on, you mentioned the word duff, and some people are probably thinking, why is he talking about a fictional beer from The Simpsons? Duff is another word for mulch, and it’s the fallen leaves, the small branches that basically can carpet a forest floor, which is their mulch. It’s an actual mulch, just like we’re always talking about the benefits of mulching your garden because it moderates soil temperature. It moderates soil moisture loss. It helps aerate the soil as it breaks down. It builds up the microbiology in the soil. And also when you get a heavy rainstorm, that layer of mulch can also help break up the impact of the water on the soil. Because on bare soil, when it rains really hard, it actually compacts the soil, removing the air. So that duff layer, that mulch layer, helps that water more slowly trickle into the soil so it penetrates deeper too. too. Besides, we don’t rake the forest. Maybe reconsider those leaves that are falling from your trees every fall. I’ve gotten into the habit of collecting the neighborhood oak leaves and grinding them up with either a mulching mower or my weed whacker and spreading it around my garden to help improve the soil during the winter if I’m not planting a cover crop.
Gordon Mann: Yeah, Fred, you’ve got such a great method of the least expensive way to care for your soil. Most tree care companies, when they grind up the chips, we can still get them to drop them off at our house for almost for free without having to haul them away to the dump. And wood chips around trees are the best. And the natural organic matter of whether it’s a crop, a plant, or a bush or a tree is what those plants are used to growing in normal nature. And as humans, we think we’re doing the right thing by pulling them out. And we have this great behavior as humans of treating everything like they’re human. We do all these similes and things of how nature would act as a human is probably a better way to put that. And it’s not correct. And there’s also some new mulch products out there that people can use, such as nut husks and hazelnuts and maybe butternut. We don’t want to use walnut because they have some allelopathy to them, which can be a little bit aggressive to other competing plants. But the other ones are creating a nice mulch layer that we can put over the soil and actually do the breakdown of organic matter like you’re talking about. And unfortunately, when we add mulch, it’s not a one-time done. We have to add mulch again after it breaks down, but that’s what helps keep the soil in a well-functioning condition.
Farmer Fred: You’ve been going around doing demonstrations and talks about the healthy soil for healthy trees, and you talk about the basic building blocks for cultivating a healthy tree life. What’s in that soil for a healthy tree? Water, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, zinc, copper, boron, molybdenum. All right.
Gordon Mann: Yeah, there’s exopolysaccharides, ESPs, cider O4s.
Farmer Fred: But what’s interesting is all of those soil elements can be accomplished with organic matter.
Gordon Mann: Correct. Humans are so used to taking two tablets and call me in the morning and give me a pill to take care of what I’m doing. That we think that by fertilizing our trees, we’re helping with the exact same thing.
Farmer Fred: Now, we’re not talking fruit trees here. We’re talking ornamental trees.
Gordon Mann: Ornamental trees, right. And even fruit trees, there’s some fertilizers that are specific towards improving the fruit production. And that’s different than just trying to throw extra nitrogen and stuff in the soil to get it to grow faster.
Farmer Fred: And we have talked about nitrogen on this program, about how it does spur new weak growth that’s very attractive to insect activity and not necessarily good insects either. And the same is true if you start adding fertilizer to a tree that doesn’t need fertilizer. If it’s got that layer of leaves on the ground, that’s enough to feed that tree, isn’t it?
Gordon Mann: It usually is. And again, because we start with soil that was not natural, and then we’re changing it, that some of the things in the soil are not there. And trees typically only need two things. Water and organic matter. The organic matter will break down and improve the soils and help the roots do their job and help them break down what’s in the soil and free up the elements that they need to grow. And by creating enough organic matter, which builds up the bacteria and the fungi in the soil and the biodiversity helps the trees be more healthy. But typically the humans think we want something to turn around overnight, and so we don’t give the soil the chance to do the long-term development that it needs that’s going to eliminate the need to do all these shots of nutrients that we get from fertilizers.
Farmer Fred: Let’s talk about your travels throughout Northern California and assessing especially backyard trees, residential trees. What are most of the problems you’re seeing associated with those trees?
Gordon Mann: I guess the problem we saw was a result of the drought. The wonderful way the state of California manages its water. Instead of trying to help people and be educated and say, we all have to use less water, we all have to do these things properly and deep watering our trees and not so much throwing the shallow water on the turf and not relying on how much rain we get each year to how we are going to behave. Unfortunately, that’s what the state does. And so when people tell you you have to stop watering their grass, they also stop watering their trees. One of the things we designed was we called stealth tree watering, where we have people dig a 12-inch wide, excavation of their lawn and putting a soaker hose in that spiral excavation, covering it with mulch. And then very slowly turning on the water so it bleeds out very slowly and drips into the ground and actually does go into the soil without greening up the grass next to it. And the mulch helps cover it so no one can see it and they can keep their trees alive. Because as soon as people cut off the water to their lawns, they’re cutting off the water to their trees as well. And unfortunately, most of the trees have learned to rely on that water from the turf watering.
Farmer Fred: And that tree may not even be in the turf. It may be adjacent to it, but a tree’s roots can travel a long way, and they’ll go a long way to find water.
Gordon Mann: Correct. And one of the problems we have with most of our nursery stock is that they’re grown in containers, and more people are trying to use air pruning to stop the roots from circling. But as soon as we pull a tree out of a container, we can see all the roots that have circled. And if we’re fortunate and the people growing it, every time they moved it from a smaller container to the next larger one, they actually did root pruning to get rid of the circling roots. The only roots we have to deal with at planting are that last layer of circling roots where we have to either prune them or something because they don’t just go, I’m free, I’m out of the container. They stay right where they’re at, even after we pull them out. And the people that just stick it in the ground like a wine cork, the tree is going to continue to grow in a circle. And the first thing I do when I visit people’s property with young trees is I give the tree a little shake. I grab it anywhere from 12 to 30 inches above the ground and wiggle it. And if I can see the container size moving in the ground, the tree is not rooting well. And the choices we have then are we can root prune it right then. If it’s been really recent, we could pull it out and transplant it. Or we could try transplanting it as been for a while and root pruning it and replanting it with much more healthy structural root system.
Farmer Fred: We’ll have link in the show notes today about the correct way to plant a tree [https://sactree.org/tree-care-tips/how-to-plant-trees/]. And you have to pay attention to the hole. I think the old saying is dig a $10 hole for a $5 tree or something along those lines. But basically, that hole should be wide, not necessarily deep, but wide. And when you plant that tree to maybe if those roots are going round and round in that root ball is to score the root ball with a sharp object on four sides and maybe across the bottom and try to spread the roots out so that they will go out and help fill in that space that you just dug out like a six foot diameter, maybe 10, 12 inches deep. It depends on the size of the container that you’re planting. And by the way, don’t plant your trees in containers. Take them out of the container first.
Gordon Mann: Yes. And, you know, it’s really interesting. The Sacramento Tree Foundation has had this pedestal method of planting trees pretty much for the last 30 years. And when I brought that up at the industry standards meeting, my coworkers and my professionals around the country called it a boutique planting method, which kind of shocked me because our volunteers do that all the time with very little training. When you dig the hole too deep and put the soil back on it, we can’t compact it to the type of aerated density that it was before we excavated it. And so the tree will settle. And one of the number one ways to kill trees is to plant them too deep. So the pedestal method is we take the tree out of the container and, We measure what the depth of the root ball is. Then we dig where the tree is going to go to only that height or even that height less one inch.
Gordon Mann: And then around that pedestal where that tree is going to sit, you can go as crazy as you want with your excavation. We usually recommend at least two times the root ball diameter, but you can go three, four, five times root diameter. And outside of the pedestal, you can dig deeper. And if you have a hard pan outside the pedestal, you could punch through the hard pan so the water can actually drain the planting hole and you can create a really wonderful environment for your tree to grow. And because we’re talking about organic matter and things, a lot of the soils we have don’t have organic matter and that’s where the mulch we’re putting on comes in. And then we water the tree. The only roots the tree has, whether it’s a ball and burlap or a container, is the roots that are moved on to the site. So we have to keep that root ball moist, and then we have to slowly expand the moisture outside the root ball so the roots can grow outside the root ball. And the more we loosen and break up the soil into digging those bigger holes, the better the air and water can actually flow in what was the original compacted soils in most developed neighborhoods or sites.
Farmer Fred: Many people, when they’re planting a tree, They want to do the tree a favor, and they buy some really nice potting soil, potting mix, and don’t put the native soil back in there. Instead, they’ll just fill it with potting mix soil. That can be a negative, can’t it?
Gordon Mann: Can be. The bigger the hole you dig and the more you mix in some of the potting soil, so you increase some of the organic matter in that really large site, the better off it is, because as the roots do grow with the soil genomics and biomes, they pull those things with them, and they keep moving them through the soil. But I wouldn’t replace it completely. I would just mix in some organic matter, maybe up to 8% or 10% at the maximum, into the soils, and I would do it over the entire area that I dig out really large, and that may help the tree establish a little faster.
Farmer Fred: And you mentioned, too, that you add mulch, but that mulch is only a top dressing, correct?
Gordon Mann: Correct. If you’re using topsoil, it usually is a combination of... A silt loam, which will have both clay and loam in it. It will have some organic matter as well, light. You don’t want heavy organic matter. You do want light organic matter. And then you add more to the surface and let it slowly get broken down and move through the soil.
Farmer Fred: Yeah, we should point out too that if you’re adding compost to that hole, even if it’s just eight or 10 percent, compost tends to break down. So it’s going to settle. So you do not want to plant compost beneath the tree. You want that pedestal to be the native soil, I would think.
Gordon Mann: Native unexcavated soil. You want that to be unbroken up because as soon as we loosen it up and put it back in the hole, it does settle. The people that do root grinding and all that, they take the wood and the dirt and they grind it up into pulverized and they usually mound it. And then with a couple of years, that mound is level because that stuff naturally settles.
Farmer Fred: Which is exactly why you need to replace mulch every few years, because it’s really a living thing and it’s breaking down. It’s feeding the soil. So you’re really helping out your trees and your shrubs when you do use a natural mulch like chipped and shredded tree branches. Now, one good tip I know for planting that tree at the correct level where you want about one inch of the existing soil ball of the tree from the container above grade is to lay your shovel across the hole. And then when you place that tree soil ball on that pedestal, you want that top one inch of the existing soil ball to be just about a little bit higher than your shovel.
Gordon Mann: Yes, and that and also once you take the tree out of the containers, sometimes the root ball starts to disintegrate. It’s just that’s what soil does. It falls apart. It’s not supposed to be packed together like a clay thing you make pottery out of. And so by having it higher, if you do get a little bit of the bottom to fall away, you still don’t plant the tree too deep.
Farmer Fred: I guess we should get into one reason why people like to plant trees is for privacy. I remember years ago during a technical advisory committee meeting at the Sacramento Tree Foundation, there was just this rush to try to find tall growing, fast growing, narrow trees for compact backyards to give people the privacy they wanted. And usually as a result, and this has been going on for 30, 40 years, they tend to plant the trees too close together to try to get instant privacy.
Gordon Mann: Yes, and even landscape architects, they’re taking a site that has nothing and trying to make it look attractive. They’re going to put the trees very close together just because you want to look nice. Otherwise, it looks like a desert with a couple trees on it. And so they do put things together. The only benefit about that is because they have so much irrigation, As the initial trees that we’re going to keep on the site over time grow, they already have irrigation in place because they have additional irrigation for trees that will probably be removed because they’re overplanted and they’re growing the canopies together.
Farmer Fred: Causing all sorts of other problems, too, usually with fences because they tend to plant that row for a privacy screen way too close to a fence line.
Gordon Mann: Yes. And again, we think about what we’re doing from our side of the fence and not the other side of the fence. And if you’re a property owner and your tree is going onto my property, I have the right to prune it back to the fence line as long as I don’t kill the tree and don’t do too aggressive pruning. And if you want to keep the tree with the kind of a balanced canopy or a balanced crown, it should be planted a little bit in from the edge of the fence. Plus then the roots are going to have less impact. And if I do have to do root pruning and put a barrier in. The earlier in the tree’s life I do that and the farther from the trunk I do that, the more natural root system I’m going to have with that tree as it grows bigger. The worst time to root prune is when the tree has got large woody roots because if we cut that root close to the tree, everything that extends outward from the point we cut is lost.
Farmer Fred: Yeah, and those trees could be supporting each other.
Gordon Mann: Yes, sometimes the roots do graft together. But the biggest thing is when we do work on our trees, we want to avoid unplanned failures. We can do things to improve the soil and do things to help improve the health of the tree. Sometimes we do add some fertilizers with our organic matter. But for the most part, we can try and keep these trees growing, especially with water and organic matter. But we can’t stop unplanned failures once we’ve taken away the structural support the tree has. And one way you can look at this with a great model is you can put a wine glass on a cocktail plate or a dinner plate and they take trees out of the field, field grown trees and fall the burlap. They’re basically taking the tree that was the cocktail plate and coming out with the wine glass or the champagne flute base. And when we start root pruning, if you chip away the base of a wine glass or a champagne flute, you’ll see how little you have to take off for that thing to fall over. The only difference between that model and a tree is the flute or wine glass fall in the direction of the chipping, and the tree falls away from the root pruning usually.
Farmer Fred: Let’s take our pruning talk above the soil level and talk about what people are doing to their trees as far as pruning goes. A lot of people don’t know the difference between a heading cut and a thinning cut when it comes to pruning. And most people are just doing heading cuts, chopping a tree willy-nilly to get to the height they want with little regard for the health of the branch that’s left over. Which usually when you do that, you end up with many, many more branches coming out of that cut that are all more weakly attached.
Gordon Mann: They’re more weakly attached and are growing so close together that they can’t grow to maturity without pushing on each other. One of the features of that is accluded bark where they grow and smash into each other. And then when those tree branches actually fail, you can examine the top and see there was no connection in the top anywhere from a quarter to half of the way those branches are touching each other. The best way to prune a tree is to allow it. And because we’re allowing our trees to grow mostly in open areas, they’re growing a little wider than they would and taller and skinnier than they would in the forest when they might be close together. And so what you really want to do is you want to take away the end weights on some of the branches that reduces the loading. When we get branch failures, it’s because the weight and loading of the branch is stronger than the attachment. So when we have those heavily over pruned trees that are basically the hard heading cuts and the branches sprout together and aren’t thinned out the attachment is not complete as i explained earlier and so at some point they do fail.
Gordon Mann: Which is really unfortunate because when the branches break without pruning we lost all our pruning options we now have this sheared off branch we have to see if we can take away the shearing and still get the branch to grow and then once or If the new branches do sprout out and the shoots sprout out, we have to prune to manage them. And most nurseries, they grow trees like they take a baby tree and make it look like a mature tree. They strip up all the branches on the lower bark to a tuft on the top where they’ve topped the tree. When we get bigger, woody branches and we make these large heading cuts and topping cuts, the likelihood of decay is much greater because the trees don’t heal. They seal or cover and take so long for their wound wood and their callus to grow over those pruning wounds that they expose that open wood to decay, which they can get into the tree and cause structural problems over the life of the tree.
Gordon Mann: The other thing I’d love to talk about is, you know, people have heard plant the right tree in the right place. That to me is a mantra from all the electric companies that have to prune to clear their wires as a way to avoid expending money pruning trees for their wire clearance.
Gordon Mann: What really has to happen is trees are actually a wonderful community or an individual asset. What we want to do is we want to figure out why we’re growing the tree to begin with. Then we’re going to grow the right tree in the right place for the right purpose.
Gordon Mann: So if we want the tree for shade or for screen or for flower or for fruit, they’ve done the iTree Studies [https://www.itreetools.org/tools/research-suite#:~:text=The%20i%2DTree,in%20forest%20advocacy], which is probably since 2003, we’ve been getting results from iTree. It’s a free computerized program that the Forest Service has sponsored with some of their research grants. And it’s shown us that from the first zero to seven years of a tree growing, we don’t get any benefits from the tree. We’re investing money and time. And because the canopy is so small, we don’t get any benefits back. The leaves are the worker bees on the trees, and the leaves are what do the photosynthesis and do the shade and do the air quality. And so if we can’t grow the tree to maturity, the tree from 7 to 15 years starts to break even on its return on investments. Then for 15 to 20 years, we’re starting to get a little bit. And 20 years to maturity is just pouring back the benefits with the crown size. And so if we can’t grow the tree to maturity, we’re never really achieving those benefits. So the idea is how do we locate the tree? So we move away the competing infrastructure and utilities. So if I have to fix a sidewalk or if I have to fix a curb or have to fix an underground line, whether it’s electrical, water, sewer, gas, communications. I can do those repairs without having to cut so many roots that I have to take the tree out. Then I can grow that tree to maturity and still take care of all my infrastructure. So the idea is that we figure out why we want to plant the tree, then we figure out what space we have, then we determine which potential trees we could plant in that space.
Gordon Mann: Then we look at the characteristics of those trees, evergreen or deciduous, nice flowers, nice fall color, fruit if we’re doing it for crops. And then we pick those trees and we actually try and have some diversity so we don’t have rows and rows of the same trees. Because those of us that have heard of Dutch elm disease, chestnut blight, emerald ash borer, eucalyptus borers, and psyllids, they’re usually attracted to one species. So if we have a row of species, we just create a smorgasbord for either a current insect or an invasive insect.
Gordon Mann: And if we look at the city of Milwaukee, who has some of the best records and best research from some great research professors in Wisconsin, when Milwaukee got hit with their Dutch elm disease in the 1970s, it took until about 2020, about 50 years for the canopy to restore itself. It was lost by the loss of all their elm trees. And if you look at the emerald ash borer cities in the Midwest, in the Northeast, and in Southern Canada, they’re going to be 30 to 50 years to restore their canopies that are lost from all the emerald ash borer damage to their ash canopies. And so what we really try to do is getting some diversity in place, maybe not have more than two like trees in a row, find trees that have similar canopies and crown shapes and fall color, and have a little bit of diversity in the species, but as similar a uniformity as humans seem to need.
Farmer Fred: And don’t forget to maybe throw a few native trees into that mix as well.
Gordon Mann: Yes, and native trees are a great thing to have, and we have a great history with them. But as soon as we take that site and scrape all the soil off and compact it, there’s no guarantee the native trees are going to do any better than any other tree. And if you look at the number of native trees we have in any ecosystem... If we only have two or three native trees, we can’t have diversity. If we have 10 or 12 native trees, then we have a great palette to work from, and we can share our native trees with a few introduced trees and have a wonderful, natural, and attractive landscape.
Farmer Fred: And again, we will use the term hydrozone, where you want to match up the watering requirements for the plants that you are irrigating.
Gordon Mann: Correct. And it’s not just the hydrozone, it’s the availability of water. In California, we get no natural rain typically from April til October. We might get an occasional rain. We’re getting more a little bit the last couple of years, but they’ve just been a spritzer. And the rest of the time and with the heat we get getting up into the 90s and the 100s and triple digits, that water evaporates out and the trees do evapotranspiration pretty quickly. And so most of the artificial and supplemental watering that we do has to be repeated on a weekly to a two-weekly basis. And that watering should be very slow and deep watering that goes deep into the soil and put on under the mulch. And then the mulch helps reduce the evapotranspiration and evaporation from the soils that you talked about earlier and helps to contribute longer between irrigation applications.
Farmer Fred: And again, that spiral you mentioned is a great idea where you are laying down either a soaker hose or an inline drip irrigation tubing in a spiral that gets wider and wider as it goes out so that the whole drip line of the tree, if you will, which extends from the trunk to the outer leaves, has the availability of water. Putting one little drip emitter next to the trunk of the tree is not doing the tree any good. It’s like you mentioned earlier, that whole area needs equal amounts of water.
Gordon Mann: Yeah. One of the designs we’ve used when we were working with landscape architects is you actually can do concentric rings of drip hose, as you talked about. Or you could use a bubbler and you create a basin so that bubbler fills the basin. And you start out with the basin right over the root ball so the root ball stays alive and slowly enlarge the basin as the tree grows, because it’s not a Popeil Showtime grill, set it and forget it. It’s a living thing that needs constant attention and maintenance. And hopefully if we do it right, we’re putting in small inputs and as the tree gets bigger and bigger, we get more and more benefits from it.
Farmer Fred: Now, folks, you can take this conversation about trees and apply it to your children, by the way. The same rules apply.
Gordon Mann: Absolutely, Fred. You know, we don’t just birth childs. We don’t just plant trees. We grow them and we raise them. And you’re 100% on that.
Farmer Fred: Yes, exactly. You want your trees to help take care of you when you’re old. It’s like that. Is there anything we didn’t talk about that we want to talk about?
Gordon Mann: Last thing I would say is that you mentioned the term thinning earlier about pruning and thinning cuts. Yeah. In 2017, we extracted the word thinning from the industry standards because humans have this thing that the trees need to be thinned. The leaves on the tree are the worker bees and they perform everything. And if we, since they’re worker bees, if we compare the trees to a corporation where we have workers and productivity, if we take away a third of the foliage, and we were General Motors or Dodge or Ford, we just got rid of our night shift. If we take away two-thirds of the foliage, we got rid of our night shift and our swing shift.
Gordon Mann: And those cruel people that top the trees, we got rid of all our workers. Who’s going to build the cars? Who’s going to do the photosynthesis? The trees can’t go to the union hall and bring on new workers. The way they restore their leaves is they sprout from, usually buds and some are adventitious and some are their buds that are on the trunk and on the branches and they sprout from those and they’re trying to restore the number of workers that they lost and the attachments from the sprouts are usually weakly attached.
Gordon Mann: Branches and trunks, the way they grow, and Dr. Alex Shigo showed us this back since 1977 or 78 that the trees, they overlap and their tissue overlaps from the trunk to the branches. And that’s what holds those branches on so tightly. And when we do the heading cuts or the topping cuts and we get these sprouts, the branches are only attached by one or two years into these buds.
Gordon Mann: And it takes, if they grow really fast, that they’re trying to do to produce the foliage, they’re weakly attached and they can fail. So the idea is to get rid of the word thinning from our vocabulary and talk about only remove a branch for a specific reason, for either the health of the tree or the structural integrity of the tree, or one of our human important needs like clearance for fire damage on homes, for visibility of traffic signals and street signs, and for making sure that we’re not getting slapped in the face when we’re looking down at our cell phones while we walk. And figuring out a way to manage the way the trees grow and allow them to grow by only removing anywhere from 5% to 18% to 20% of the foliage at any annual pruning on the tree, unless it’s a really critical need. And trees that maybe haven’t been pruned in a long time have the risk of a branch falling. Because the branch falling takes away our pruning options, whereas pruning well and keeping the natural shape of the tree looking like a tree full of foliage and dense foliage is the best way to grow the trees.
Farmer Fred: So what did we learn from Gordon Mann, consulting arborist today? Well, it’s Farmer Fred garden rule number seven: “Everything you know is wrong.” because just like in this little conversation here, what terms don’t lead to correct pruning work? Things that we’ve been saying for years like remove dying branches, remove diseased branches, remove crossing branches and thin your trees. Basically, hold on. And what Gordon is saying is only prune what is necessarily good to prune.
Gordon Mann: You know, when we write the specs to say remove dead, dying, crossing, diseased branches. So if you have a dead branch, you may want to only prune it back a little bit and leave some habitat. Sometimes dead branches do that. Or you can remove the dead branch because it’s not going to impact the health of the tree.
Gordon Mann: But a dying branch, say 10% of the branch is dying, you gave me permission to remove the whole branch, even though you had to remove the 10% of dead branches.
Gordon Mann: Diseased branches, we have anthracnose and powdery mildew. And you have a diseased branch with those, and you gave me permission to go ahead and remove all those branches. And basically, you’re getting a topped tree when you thought you wanted a nicely pruned trees. Crossing branches are, depends on your perspective. You look at the tree from the top and every branch is crossing. It’s really crossing and rubbing branches. And you want to try and first reduce some of those loading weights that gets it to separate from the rubbing. Or if they’re crossing and their branches are covering the same area where we need the leaves to grow, maybe remove one or two of the one of the two branches or a pair of branches. But removing crossing branches, I can remove all of them or both of them. And then the last one would be, and thinning, thinning again, you’re just taking branches out of the tree and the tree is going to regrow those because it has to grow.
Gordon Mann: And we used to say in the industry standards that you don’t remove more than 25% of the foliage and all the pruning specifications said remove up to 25% of the foliage. Really want to move anywhere up to 5% to 12% to 18% maximum, depending on the needs and the species of the tree. And we only want to remove the branches that have to for end weight loading or critical safety issues. And that’s a different approach than just go ahead and thin every tree of 25% and make it look like you got a haircut at the barber. One of the best analogies I can relate to is for those of us that have significant others, that one of us goes to the barber and the other goes to a hairstylist.
Gordon Mann: I go to a barber, I come out, and first I point into a picture on the wall to make him cut all my hair off like the guy in the picture. And when I walk out of the barbershop, everybody knows I got a haircut. When my lovely wife walks out of the hairstylist, she’s probably paid 10 times what I pay. And she comes out, she goes, what do you think? I’m like, okay, what did they do? Your hair looks great. You know, which supermodel do you want to look like? They don’t look like an army sergeant that just came out of boot camp. They look like the nice head of hair with a beautiful style. And when my friends come out of hairstylists, their hair doesn’t look like it’s been cut. It just looks very attractive. And if we can kind of prune our trees that way, I think we’ll be way ahead.
Farmer Fred: I hope you have a comfortable couch to sleep on.
Gordon Mann: I know.
Farmer Fred: We’ve been talking with Gordon Mann. He is a consulting arborist with the California Tree and Landscape Consulting Firm. He has a website called Mann with two N’s, mannandtrees.com [https://mannandtrees.com]. If you don’t know your trees, if you don’t know what kind they are, if you have questions about your trees, it pays to invest into a consulting arborist. Gordon Mann, thanks for setting us straight on trees today.
Gordon Mann: Absolutely, Fred. I always enjoy your show and I really appreciate all you do to educate our public in the areas. I’m glad you share your podcast with whoever can go online and listen to them.
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