Michelle asks about planting a food forest in clay:

A friend in South GA has asked me to come help him figure out how to start a food forest on his property but all of the trees he has planted previously are languishing because of his clay soil (and he hadn’t mulched them).

Do you have any tips for working with really thick clay?

A friend just south of him says she started a few fruit trees in her clay yard by putting the tree’s root ball on top of the soil, adding soil around it to create a mound and then let the tree slowly work its way out and then eventually down. I’m thinking that would be what I wanted to try even though it might require more outside input (soil). I’d love your experience and tips.

In another project, we’re having a food forest planting day at our church’s 2 acre lot next week. You’ve been the greatest inspiration toward tackling this project.

(See my answer as a video)

Growing a food forest in clay is not impossible. There are massive forests in clay everywhere.

I remember when I was a kid, going to Spruce Pine, North Carolina, and the woods there were fantastic. They were beautiful. Great, big, happy forests. But when we did a little bit of work on my grandparents’ yard, putting in some steps down the slope, cutting into the ground with a shovel in order to put railroad ties in to make the steps, we found that the soil was like pottery clay. It was shiny when you cut it with a shovel, and it took a lot of work to dig in. It was so thick you could make pottery out of it.

In fact, we did make some pottery out of it. I remember making little heads and bowls and things and letting them dry, and then we fired them in a campfire.

It was clay. It was serious clay, yet the trees were happy.

Problems with Planting in Clay

Here’s what can happen when you plant new trees in clay, though. We had this problem before, when we lived in Tennessee, is that you dig a hole to plant your tree in. That hole in clay becomes a pit that water fills up. So, you put a hole in tree into it, and the tree goes down into it with its nice, light, fluffy soil from the pot.

And then what happens?

It becomes a spongy, swampy mess, because the water goes down into that pocket in the clay. It’s like a little pond that your tree ball is floating in, and just filling full of water, and the tree’s roots drown, and it dies.

So, how does nature deal with that? Well, my bet is that a lot of those very happy trees that are growing in your clay, would have come from seeds, that would have broke their own way through the clay, and put down roots through the existing clay, rather than basically creating a drain pocket in which the water can just drown the roots.

You’re almost making a container for water in the clay that you’re putting a tree into, which is not particularly good for the roots.

Planting in Mounds

As for the idea of planting on a mound, that definitely works.

We did that in poorly draining soil down in the Caribbean. We would make mounds that were about 18 inches tall, painstakingly digging in the hard clay, and then we would plant on top of them, and our trees and plants would not drown.
However, if we planted them flat in the ground, when it got swampy during the rainy season, they would drown.

The water has to run in between those beds, so if you have two beds like this, the water would go in between them, and there would still be enough drainage up here that the soil did not become completely saturated and kill the plants. So, that is an option. Now, the downside of doing this, if you do as your friend says, who started a few fruit trees in her clay yard by putting the tree’s root ball on top of the soil, adding soil around it to create a mound and then letting the tree slowly work its way out and eventually down is that the tree is not well anchored in the soil.

If you have any wind events, boom, there goes that tree. So, if you’re going to do that, you’re going to need it to stay in. I would consider digging down a little bit, putting your tree partway in, mounding up around it, like, like I said here, but if you’re going to do that, put a stake with it. Another thing about clay, is that clay can be chemically loosened, not by putting something toxic on it, but by adding lime, adding pulverized limestone.

Lime and Mulch and More

If you spread pulverized limestone in enough  quantity, clay will actually loosen up, because the calcium starts to make it flocculate a little bit.

You can get a little more like soil, and a little less like bricks. This is very, very useful.

Also, deep mulching on top of clay will loosen it up.

If you put a foot full of wood chips on top of it, and let it rot down, it will make it loamy, it will start to loosen it up underneath.

I would start the food forest with clay by making mounds, so there’s a little drainage around them and planting into those.

I would not add any extra soil or anything to them.

Bare Root Trees May be Better

If you could start with trees that were bare root, you might have even better luck, because they start completely new.

They’re going in the native clay soil and not inside of a little pocket of loose potting soil where the roots are going to continue to circle, because it takes effort to go into the clay.

You’re going to make them make the effort right from the beginning by starting with bare roots. And the time to plant those is usually February or March, depending on when they come out of dormancy in your area. If you can get bare root trees and put them in the ground in the clay, I have a feeling they would do better than trees that were planted from pots.

If you have forests in your area, you can grow food forests. Even if you don’t have forests in your area, you can often force a food forest to grow by starting to create the conditions that are amenable to a forest. Clay soil is not going to stop you from having a food forest. It is quite manageable. And over time, if you have mulched, if you have added lime, it can actually become loose and friable, or at more loose and more friable than what you started with.

And as for the church food forest, great work! Glad to have been an inspiration. May it do excellently.