Wood Selection Details
Making a big hugel bed requires more wood than you probably expect. If you plant to build a hugel bed, it’s a smart idea to start preparing long in advance by saving tree trunks, branches and any trimmings that will take considerable time to break down.
Note: Some types of wood are better suited to hugelkultur than others. There are certain trees that naturally produce chemicals that prevent them from breaking down quickly, and these chemicals sometimes impede plant growth as well. To be safe, stay away from black cherry, cedar, black locust and black walnut.
Additionally, avoid any wood that has been treated with harsh chemicals. Not only will this wood take longer to break down, you will also be exposing your food source to potential toxins. Stay away from pressure-treated wood like railroad ties, pallets, and anything that has been painted or stained. Untreated lumber or scrap pieces should be fine.
Creating the Beds
When you put together your hugelkultur system, remember to try to copy the natural order or decomposing materials in the real world. Think about the forest floor and the way that leaf litter and debris stacks on top of fallen trees and reproduce this system like this:
First layer: thick logs and sturdy twigs
Second layer: dry material like dead leaves or straw
Third layer: wet organic material like fresh grass clippings
Fourth layer: fresh compost and manure
Top layer: topsoil
How tall you choose to make your hugel bed is entirely up to you. To keep things manageable, some people like to dig trenches for their bottom logs to go in so that the subsequent layers of compostable materials lie flat and closer to ground level, giving the gardener more room to plant in. Other people find it better to pile logs several feet into the air to minimize the time they need to bend and stoop over.
Because the structure of a hugel bed causes the bottom log layer to both suck up water and slowly release nutrients into the soil over several years, you won’t need to water or fertilize it very often, if at all. However, the bed will have a chronic shortage of nitrogen for the first few years, so it’s in your best interest to not plant annual vegetables until the bed is fully established after a few years. Instead, you can plant potatoes, beans, lettuces and perennial vegatables. Within three or four years, your bed should be ready for squash and broccoli as well.