Arborist Answers Your Questions PART 1

We sent in your questions, so in this part one episode, Davey arborist Lou Meyer answers them! To submit a question for a future episode, email us at podcasts@davey.com.

In this episode we cover: 

• Growing trees in containers (1:03)
• How is biochar applied? (9:46)
• Chlorosis - iron sulfate or biochar? (14:42) 

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Connect with Doug Oster at www.dougoster.com. 

Have topics you'd like us to cover on the podcast? Email us at podcasts@davey.com. We want to hear from you!

Transcript

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Doug Oster: Welcome to the Davey Tree Expert Company's podcast, Talking Trees. I'm your host, Doug Oster. Each week, our expert arborists share advice on seasonal tree care, how to make your trees thrive, arborists' favorite trees, and much, much more. Tune in every Thursday to learn more because here at the Talking Trees podcast, we know trees are the answer.

Folks, get ready because we have something brand new for you today. I'm so excited that we put this together. We've got your questions. Lou Meyer is a regional business developer for the Davey Tree Expert Company in the Atlantic region. He's been on the show just about more than anybody. We love seeing him. Lou, are you ready to answer these questions?

Lou Meyer: I am always ready to talk trees with you, Doug. I'm very excited that we've got fans from all across the nation writing in questions about their leafed friends.

Doug: [laughs] If you get stumped, though, you're fired. I didn't know if they told you that.

Lou: I know. I'm sweating bullets.

Doug: [laughs] All right, let's get right to it. This is from John. "I live in Zone 6, and our property is mostly concrete and hardscape. We do get a good amount of sun, though. I have wanted to grow a tree on our patio, but I'm told not to attempt it. Any advice would be great." Well, Lou, we've talked about growing trees in containers before, but I don't remember what you said.

Lou: Yes, we had covered that. I want to say it was in early 2024 or maybe late 2023. I can go back through my notes, but if you search the Davey podcast history, you'll find one on container-grown trees. This is something that a lot of people ask us about because most of us live in urban and suburban situations, where we don't have giant lawns to grow big trees. That's perfectly fine. Anyone can be a gardener. Anyone can be a tree lover. What we talked about then, and what I still stand by, is you can grow trees in containers in places, where historically you've not been able to.

Doug: Let's talk about choosing the tree. I'm sure you would want to get more information on exactly what kind of sun is there and then what the purpose of the tree is going to be. Making that decision is a little easier. Just in these broad brushstrokes, what would you use?

Lou: The questions I would ask first off, and this is the questions that we would ask anyone who's planting a tree, we're more limited by a container with the scope. Still, the same questions are, where are you living? John said Zone 6. We break up our horticultural zones or USDA, United States Department of Agriculture hardiness zones based on temperature, degree, growing days. A few other things.

Zone 6 is where a lot of people live. If you look at the USDA map, Zone 6, you are in most of Kansas, Missouri, southern Illinois, most of Indiana, all of Kentucky, all of Ohio, almost all of Pennsylvania, except in the mountain regions. Half of Michigan. You got northern New Mexico. Most of Utah, except the mountains. Zone 6 is a very popular place to live.

There are a lot of trees that grow there. Now, if you're in a different zone, you're going to look at different plant material. Your local nurseries can help you find that. Your local arborsists can help you find that. John also wrote in that he's in full sun or a lot of sun. That's really helpful. There are trees that like full sun. There are trees that prefer shade. Of course, there are trees in between, like anything. Then we're going to talk about exposure to the elements.

If your patio is on the northwest side of your house, that's the one that gets hit with those winter winds all the time. Or, is your patio on the southeast or northeast side of the house, that might be a little more protected. Wind exposure is really big when you're talking, especially about container-grown trees, because the biggest concern for container-grown trees are those root systems. They're freezing over hard in the winter.

For John, Zone 6, with a good amount of sun, you're not going to want a giant oak tree, arborvitae, green giant. This is where we talk about limitations on container-grown. You want to think about things like a Japanese maple. A Japanese maple is an excellent container-grown tree. Most container-grown trees I see are Japanese maples. Eastern redbud is another popular one.

You can find all sorts of cultivars, too. For instance, one of my favorite eastern redbud cultivars is the forest pansy. This particular cultivar, instead of having the bright green leaves, has a real dark purple leaf. If you have a house that is white siding on it, or I used to live in a yellow house in Cincinnati, we planted a forest pansy. That purple offset with the yellow was spectacular.

Some of the magnolias can do really well in containers as well, like a saucer magnolia, for instance. When you plant these things in a container, since John has a lot of hardscape and concrete, and he wants to put it above ground, when you plant in a container, you want to be able to consider moving this container. Again, depending on weather conditions and other things, you may need to use a dolly to pick this thing up and move it to a different location.

You don't want to use soil from your backyard. That's going to be very heavy, a lot of clay, likely. Even loam is heavy. We use totally different stuff for planters. [unintelligible 00:06:01] you need to think about is a potting mix or a potting soil. Those are two different things. Refer back to the last episode about it. They're lighter weight. They've got more peat mixed into them and other nutrients that will help maintain soil moisture, but not have the density of your typical dirt, for lack of better words.

Doug: When you guys are doing a big container, is there some proprietary mix or something you're using, or do you get it from a nursery? What are you using?

Lou: We're using what's local. A lot of times, that's from our tree providers. We have local relationships with nurseries across the United States, and we have national relationships with national providers. Some of the higher profile ones that I've been involved with, the landscape architect that has designed the project, has specified the exact potting mix that they're looking for. We've gone to custom blenders for that. For your homeowner, for John, you can find bags of potting soil or potting mix at your local garden center. Those should work sufficiently.

Irrigation's tough. You got to pay attention to the irrigation of these things. I would recommend a drip irrigation system, one that will allow water to percolate into the soil for your tree to take it up. If you want to hand water it, that's fine, but these things dry out really quickly because that soil, since it's so lightweight, doesn't hold on to the moisture long. You want to make sure to keep it moist. Mulch will help with that. Mulch helps regulate soil temperature. It also helps regulate soil moisture levels.

If you have a really cold winter, those root systems can freeze. In the wintertime, you want to protect it. You could wrap it in burlap. If it's in an area that's over turf, you could put a tarp down and put wood chips around it. Arbicultural firms like Davey are always looking for places to dump our wood chips. We'd be happy to dump a load in your driveway, John. You can insulate your tree that way.

Doug: Yes, it'd only be about eight yards, so don't worry about it. It shouldn't take longer than the entire summer to spread it. That's how long it would take me.

Lou: It's a great exercise. Builds character, John. Your other option is, if it's lightweight and you have a real cold snap, if you could dolly it into your garage for a few days. In the wintertime, it's not photosynthesized in any ways, so it doesn't need that sun exposure on the leaves to create food. That's another way to protect your tree.

Doug: What do you think about drainage for the container? What do you think about the size of the container? For some reason, I have in my head, this big, giant concrete container. I know you're not going to be able to move it, but that's just what pops up into my head when I see a tree growing in there.

Lou: Yes, the concrete containers are pretty popular. There are concrete alternatives that are like concrete but super lightweight that are much better. Yes, you're going to want a large container. The bigger the container, the happier and healthier your tree is going to be, unless you're bonsaiing it, which is an entirely different episode. Yes, there's plastic containers that are lighter weight also.

You do want to make sure it drains. You want to put a layer of gravel at the bottom of that tree well, and then the soil on top of the gravel. You want to make sure there are weep holes to allow the water to come out. I know we said that the soil doesn't hold on to moisture long, but the last thing you want is a cauldron of water for this tree just to sit in.

Doug: Well, I think we've taken care of John. Now let's move on to Cynthia, who has a couple questions, actually. She says, loved the podcast on soil. Jason mentioned biochar at the end. It sounded like it would help make micronutrients

available. Let's start off with biochar. What is it? Her question is, how is biochar applied?

Lou: Great question, Cynthia. I'm so glad that you listened to Jason's podcast there. He's a good buddy of mine and does good work. Biochar is an activated charcoal product. You can make biochar out of almost anything, but the one that we like the most is when it's made of organic wood material. You put woody debris into a kiln where it is heated at a high heat with low oxygen, which pretty much turns into charcoal. That's how you create charcoal. Then we blend that with organic material.

Think of compost. Some folks like to add molasses to theirs because sugar attracts a lot of micronutrients in the soil. What this does is it creates a product that has a high cation exchange capacity. I know that's a blast to the past from high school chemistry there. We're not going to get into the weeds here, but what it means is a high cation exchange capacity allows nutrients to bond to the material much easier.

If you want your water molecules to last longer in your soil, if you want your nitrogen, phosphorus, and potassium to last longer in the soil, they will bond to a product like biochar and will hold on to it for much longer. We use it as a soil amendment. There's all sorts of other uses for it. They use it to clean ponds. They use it to clean mine reclamation sites. Charcoal is often used as a filter for all sorts of purposes. For our purposes, we use it as a soil amendment.

We apply it in three big ways. I'm sure there's other ways, but the three big ways are for your turf. If you're trying to revamp your turf, if you're trying to build a healthier growing medium for your lawn, your turf, we can apply it with a spreader. Either a drop spreader, which is more of a complicated machine that allows stuff to drop down from it. Your typical lawn spreader, though, also works depending on how the biochar was made and what form it's in.

I use one that can go through a lawn spreader. Just your typical lawn spreader that you push. You're throwing this biochar all over the surface of your soil, and it'll work its way into the soil. Ideally, and my buddy, Zane Raudenbush, will back me up on this, our turf expert at Davey, ideally, you're doing this when you are aerating the soil. You're pulling these plugs out of the soil. You're putting some biochar back down. That's going to work its way into the root system of the turf.

Even if you're not doing it then, any way to get biochar onto the turf, it'll find its way down into the soil. It'll last for 5,000 to 6,000 years. That's thousands with a T, so a long time. You get a good base of this into the soil, and you're good for a while, a couple of generations anyways. It's got a long-term lasting. That's how you do it for turf. When we're planting trees, or when we're rehabilitating soil for trees that's been compacted, or trees that have been damaged in construction, and we just want to really revamp that soil, we'll use bigger pieces of biochar. We'll use an air spade or other air tool that will cut through the soil.

The best term I use is fluff it up. You're fluffing the soil. You're blasting down 8 to 10 inches, loosening the soil. Then we're throwing this biochar on top of that fluffed-up soil, and then using this air tool again to work the biochar down into the root system of the trees. That's where it needs to be to, again, hold on to these nutrients. That's why it's such a powerful soil amendment, is it holds on to nutrients. It holds on to water molecules, and improves the soil structure. That's through air spade.

The final way we sometimes use it. We're getting into it more and more, is a liquid injection. You can buy liquified biochar that we'll mix in with our fertilizer, our patented fertilizer. Davey Arbor Green PRO. We are injecting that liquid into the root system when we are injecting the fertilizer. Again, the benefit of biochar is it helps hold on to those nutrients longer, so it elongates the effectiveness of those nutrients.

Doug: That explains that. That's good stuff, Lou. Cynthia's got some other questions, though, too, and it does relate to biochar. She has a redbud that looks chlorotic. She sent us a picture. Did you take a look at that?

Lou: I did.

Doug: Master gardener friend suggests it is an iron deficiency, and that I might try some iron sulfate at the base of the tree around the roots. Will biochar be an option? Between the two, which is a better choice? Lou, I'm sure you get a lot of these, where someone sends you a picture and wants the answer. Can you answer a question like this by just looking at that picture?

Lou: I cannot definitively answer a question, but I can provide some answers. I'm probably going to come back with more questions, but those questions are going to be purposeful. It's not just random questions. Looking at Cynthia's redbud, I wouldn't rule out chlorosis, so a lack of iron in the soil. This is something we see a lot. Redbuds are more rare with that. We see it a ton in oak trees. Chlorosis in oak trees is a normal thing for us to deal with. We counter that sometimes with iron injections. Iron sulfate around the base of the tree can help as well.

Changing nutrient makeup of the soil sometimes has to do with a lack of that nutrient. Interestingly, though, sometimes it has to do with the pH level of the soil. Your pH level, if you remember, again, back to high school science, you've got your alkaline and your acidity. 0 is one, 14 is another. Then 7 is a neutral right in the middle. Most of our plant life prefers a little more acidity, but some like more alkaline, and different ones have different temperaments. Different pH levels in the soil allow for different nutrients to be taken up.

Without looking at a chart and remembering all the ins and the outs, I'm just going to say maybe. Iron needs more alkalinity to be available for the trees. Again, it's a maybe. I don't have it in front of me. I'm not the soil scientist. You have to have your pH right. No matter how much iron's in the soil, if the pH isn't correct, it doesn't matter. What I would recommend to Cynthia or any of our listeners is to get a soil test to know what your pH level is.

If you do a comprehensive soil test, it'll tell you what nutrients. It'll tell you what the cation exchange capacity of your soil is, your organic matter makeup. Really, before anyone tries to alter their soil, you need to know what's there first. Get a soil sample so you know. Maybe it's just the pH that you need to change. Maybe there's plenty of iron there. Now, the second part of her question, well, her first question is, will biochar be an option?

Biochar won't change the iron level of your soil. Between the two, which is a better choice? Biochar doesn't have a nutrient consistency. It's the void of nutrients. What it does is it helps build better soil, which in turn helps your soil hold on to nutrients longer. Between the two, which is a better choice, for this particular problem, the iron is more important. I would, A, get a soil test first. B, if necessary, I would apply the iron. C, if you have the means, I would include biochar to help that iron stay in the soil much longer while at the same time improving the soil.

Plant healthcare, much like human healthcare, there's a lot of layers to it that have to work together. If you have a vitamin C deficiency, your doctor might say, "Hey, take some vitamin C pills." It's probably better to eat some apples, eat some oranges, because in addition to vitamin C, they're going to have other nutrients in them that will help unlock the powers of that vitamin C. It's no different with soil and trees. A lot of things work together for their success.

Doug: Well, Lou, we only got two questions answered. This is part one, and I don't know how many parts we're going to be doing because we've got lots of questions. For our next question episode, we're going to go right back to Cynthia because she's got another long question, which I think is really interesting. Stay tuned for that. The next time that Lou and I get together, that's what we're going to be doing, answering more questions. As always, Lou, thanks so much for the time and the information.

Lou: Great talking to you, Doug. See you next time.

Doug: Well, as I said, that's Part one. We were going to have a Part two, for sure, probably a Part three, but we're still looking for questions, and there's a couple different ways to send them to us. Send us an email to podcasts@davey.com. That's P-O-D-C-A-S-T-S at D-A-V-E-Y C-O-M. You can also click the link at the end of our show notes to text us a fan mail message.

Your questions can be on the podcast. It's going to be fun. Don't forget to tune in every Thursday to your Talking Trees podcast from the Davey Tree Expert Company. I'm your host, Doug Oster. Do me a favor, as always, subscribe to the podcast, so you'll never miss a show. As always, we like to remind you on the Talking Trees podcast, trees are the answer.

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