Tyler Close

I built my first hugel last year and am currently fixing it up for the next rainy season. The top layer of soil, leaves and twigs broke down and settled a lot more than I was expecting, so I've got a lot of holes to fill in. Luckily, I followed Bryant's advice to use upright logs for the bottom layer, so it's been easy to fill in the holes by just pouring more dirt in. With horizontal logs, fixing this error would have likely meant tearing the whole bed apart.

When building the bed, I really thought I had packed enough dirt in. I also watered the dirt in as I was going. I suspect dirt and compost that's been fluffed up by digging is always going to settle so much that it is hard to pack in enough of it during initial construction. Using upright logs makes it a lot easier to deal with this issue. First timers seem especially likely to run into this problem so should all be advised to use upright logs.

A lot of information online suggests that my zone gets too cool in winter for avocado, but there are a few mexicola grande trees that are doing well in my neighborhood. However, they can grow to 25 feet and are spreading rather than columnar. I've got enough space to put a 20 foot separation between them, but am going to check the nurseries for a columnar variety that's also cold hardy.

The trench my wife and I have dug is a rectangle 5 feet wide and 22 feet long, with the long side on the north-south axis. The plan is to put avocado trees on either side of the north end of the hugel. The avocado varieties are supposed to grow tall, but narrow. The first elderberry will then be planted on the hugel, about 6 feet in front of the avocadoes. Then 5 feet down from the elderberry comes a couple of dwarf citrus, again on either side of the hugel, then finally the second elderberry. I hope this creates a sun trap effect, with the elderberry in the understory. The elderberry should get plenty of sun, especially as the sun swings around and hits the hugel from the side in the late afternoon. I also want them to get some shade from the citrus, since the summers here routinely spend a few weeks in the 100s. When grown, the whole arrangement should also provide a nice evergreen privacy screen between the street and the house.

We've started laying the wood in and are using vertical logs for the lower half of the hugel, as you suggested. It's astonishing how much wood fits into a trench of this size. I've also now got a lot of black clay that I'm trying to figure out what to do with.

Different elderberry varieties have greatly different sizes, some of them clearly trees rather than bushes. The varieties I've been considering all claim to top out at about 6 feet. That seems in about the same range as a blueberry bush, which I've read do well on a hugel. As you've noted, the elderberry also prefers the moist soil that a hugel provides.

I'm planning to use the edges of the hugel for actual tree size fruit trees, so also don't want to give up that space for the elderberry.

Since we're talking about it, another question I've had is how close to the hugel to plant the fruit trees. I haven't found anything more specific than "next to". Is two or three feet away from the edge of the hugel the right spacing?

I like the idea of spacing the logs further apart under the bushes. The extra soil might also prop up the hugel more in that area, so that even if the surrounding parts fall below the soil grade, the bush's root crown might stay above the grade. Thanks.

By shrink, I'm mostly concerned with how far down the top of the mound will drop over the full lifetime of the elderberry bush that's planted there.

My current plan is to dig down 3 feet and build a 6 foot mound, so that initially there's 3 feet of hugel above the soil grade. I think an elderberry bush has a productive lifespan of about 20 years. So the question becomes, will a 6 foot hugel shrink to less than 3 feet in 20 years, including the initial settling?

To keep the mound above the soil grade, I'm wondering if I should build the lower half of the hugel with upright logs closely packed with soil. Maybe roots would then fill in the gaps left by the rotting wood and stitch the soil columns together.

I'm building a hugel that will be home to a couple elderberry bushes. It's in the front of the house, so I'm digging down to accommodate a deep hugel without having a huge mound. Since the bushes are long-lived, they will sink as the hugel sinks. I don't want the bushes to sink below the surrounding soil grade level, as that could put them in a muddy pit. So, I need some idea of the amount of shrinking to expect over the lifetime of the hugel/bush pairing to know how much of the hugel can be initially below the soil grade level. I realize the shrinking will be influenced by what I put in the hugel and how I pack it, but what would be a good rule of thumb?