From green rooftops to living walls and mycelial bricks, professional designers are getting more and more sophisticated with the art of incorporating living organisms into built environments. Biotecture is no longer a futurist dream, but has become a practical reality. But as much as it has become a part of high-tech building design, the principles of living structures are timeless and so simple that you can play with them — and make a fun and useful structure — in your own backyard.
The supple branches of willow trees are a prime material to start with. We’ve all seen baskets woven from willow branches, but it’s possible to weave the branches while they’re still alive to create almost any conceivable form. People have made living chairs, small bridges, fences, play structures, conceptual artwork, and many other designs with willow. This article gives step-by-step instructions on how to build a dome-shaped willow shade shelter; perhaps one of the simplest possible designs, and one that can be morphed into more complex structures if you get inspired.
Before getting started, it is important to understand the characteristics of willow trees that make this artform possible. Willow branches are long and pliant, which allows them to adapt into almost any form imaginable. Wherever two branches touch each other, the wood will fuse into a solid joint – the trait that gives structural integrity to a willow dome. Plus, willows have an incredible growth rate. Creating a living structure takes as much time as is necessary for the plants to grow, so it pays to work with a species that grows 6 to 8 feet a year.
Willows also have the magical ability to quickly form roots from any branch that is cut and stuck into the ground. This means that it’s easy to propagate dozens of trees in a short period, which, as you’ll see below, is the key to making this design work. Finally, it’s easy to find willow trees to propagate from, as they’re commonly found along streams and wetlands in almost every corner of the globe. Don’t worry about taking cuttings for your willow dome project – the trees re-grow immediately and almost seem invigorated as a result of being cut back. One of the great things about this project is that it doesn’t cost a thing. You’ll only need a few basic tools, and access to a stand of willow trees.
1. Cut willow “posts” that are 1- to 2-inch diameter by 4 feet in length.
These need to be as straight as possible. You’ll notice that certain places on any willow tree will have long straight sprouts that make the perfect material to start your willow dome. The number of posts needed depends on the diameter of your dome and your goals for building it – read through the rest of the directions for more clarity on how many you’ll need for your project.
2. Use a stake to measure out radius/diameter.
In a flat part of the yard, pound a wooden stake (you can use one of your willow posts if you like) into the ground at the center point of where you would like the dome. Tie a string to the stake and cut it at the length equivalent to the planned dome’s radius – any size from a 3 foot radius (to make a 6-foot diameter dome for little people) to a 10-foot radius (for a large party dome) is feasible.
3. Add the willow posts.
Pound the willow posts into the ground in a circular shape around the center stake, using the string as a guide to make sure all posts are equidistant from the center. Of course, the softer the ground is, the easier this will be. If the soil is dry, you’ll want to run a sprinkler over the area for a few hours before starting to make sure it is soft and saturated – willows love water. Pound the posts in to a depth of one foot, keeping them as straight as possible.
- Deciding how close to space the posts: You can space the posts anywhere from 2 inches to 2 feet apart, but it should be consistent around the entire circumference of the circle. By spacing them so they’re almost touching, you’ll end up with a solid wooden wall within a few years, as the posts will fuse into a single unit as they grow together. Otherwise, there will be space between the posts, resulting in a structure akin to an open air gazebo.
- Entrances: Decide how many entrances you want for the dome and leave 2 to 3 feet of space between posts at these locations.
- Note: Use the posts immediately after cutting them or stick them in a bucket of water to preserve their vitality until you’re ready to use them.
4. Encourage the willows to grow.
The posts should begin to sprout within a month after they were ‘planted’. Water them absolutely as much as possible; you can’t overwater willow trees and the more you water, the faster they will grow. Spreading all-natural fertilizers around the willows (such as composted manure, bone meal, fish emulsion, etc.) will only accelerate the growth of your dome. Replace any posts that do not begin sprouting with the others.
5. Guide the branches into the shape of a dome as they grow.
It is likely that several sprouts will emerge from the top of each post, but you should clip off all but the single most vigorous sprout from each one at first. The goal is to bend each of these toward the center to meet a branch growing from the opposite side. Once they are long enough to reach each other, each pair should be lashed together in the middle with biodegradable twine.
6. Weave side branches horizontally to fill out the shape of the dome.
Clip off any side branches that grow perpendicular to the main branch (i.e. either directly toward the center of the dome or away from it), but the rest can be woven in and out of the adjacent main branches to create a spider web pattern across the dome shape.
7. Remove branches that grow into the entryways.
As the structure grows, train two branches together into an arch over each doorway to create a hobbit-hole. The same can be done to create windows.