Build a Raised Wicking Bed

Visitors to our urban farm always ask how our raised wicking beds work. They are a smart addition to any permaculture plot or urban farm. The simplicity and ease of care seem a little too good to be true. As with most permaculture projects, at the beginning it sounds like a lot of work, but I promise you they really are the best thing we’ve built for many reasons.

Water Conservation. The reservoir can be filled and left alone to hydrate the plants for weeks at a time. Urban farmers are often busy with life outside of gardening and it’s nice to have the luxury of skipping watering days. Due to the reservoir being low to the ground, the water slowly evaporates and as it does, moves up through the soil above. Roots of the plants are encouraged to reach down toward the cool water below. Use your hose or your rain collection tank to fill. The boxes also act as a catch basin when you get a good rain. We’ve had seasons that require no filling outside of a healthy rain once per week.

Pest Control. Being raised a few feet off the ground, many furry friends will naturally leave the boxes alone. It's difficult for a bunny to notice what's above them and hop that high. The screens we added on top keep out most critters that would otherwise disturb seedlings and snack on mature fruits and veg. In particular, we have lots of squirrels and birds. The chipmunks are another beast altogether (we might post about our adorable tiny friends later, so stay tuned for that fun). The screen frames also provide a structure to lay shade cloth over top to keep delicate young seedlings from being scorched by hot sun or to protect from a surprising spring frost.

Comfortable Maintenance. The height and accessibility of the boxes make planting, weeding, and harvesting a pleasure. You can pull up a stool, or squat/kneel without breaking your back. Kids can stand and work easily. Park a wheelbarrow neatly beside or dump one straight over the edge.

They look super cute. We’ve stained our wood black to complement our style. Adorn with fairy lights. Decorate however you like. Make them into a focal point in your garden. They deserve some attention! Watch this video to get a 3D feel of our raised beds in action.

We’ve built raised beds in our other backyard gardens before, and they were ok. But some key elements make these boxes especially amazing. Here are the steps involved in building these particular beds.

1. Start with a level and flat base. Boxes can be tricky when built onto slight slopes and uneven ground. They turn out ok, but this level base is a dream for so many reasons. When we began to build our wood frames and laid them out, it was a delight to achieve a complete and square grouping of boxes, and the finished heights matched seamlessly without fuss. The overall design is pleasing to the eye and makes visual and functional sense. So although it is extra work to build a flat, raised pad, it was totally worth it. The pad is framed with 6x6 posts and filled and compacted with gravel.

2. Build the box frames. This part is easy. Just cut your length and width pieces, secure together with screws, add some reinforcing braces in the longer sections, and set in place. There are no wooden bottoms, just the outer frames.

3. Place a layer of wire mesh in the very bottom of the boxes directly on the ground. Use mesh with a tight weave, so moles, voles, and other digging and burrowing animals can’t enter from below. Secure the edges of the mesh to the wood frames inside so there can be no sneaking through.

4. Next is the pond liner. Use a good quality, thick pond liner that cannot be easily punctured. This will hold the collection of water. You’re essentially making a small pool and you want it to be water tight. Lay the pond liner in and fold it in the corners. Leave the liner loose at the top edges so you can adjust as you add and build. You can trim the edges when you’re finished.

5. You’ll need a pipe that extends the length of the box, with holes in it to evenly disperse the water when filled. We used a flexible, perforated “Big-O” drain pipe. In other boxes we’ve built, we’ve used a length of PVC with drilled holes and attached an elbow to make the turn up the inside of the box. Use what you have on hand or what you can easily source. Cap the end of the pipe in the bottom of the bed. We used a few large stones to hold the pipe in place so it didn’t wiggle around while we worked further.

6. Drill a hole for your overflow tube. You'll drill at the circumference of your tube, and make sure to drill carefully through the wood and cut your pond liner as closely to the size as possible to avoid losing water. Use a short length of tube that can reach through into the reservoir bed. Ours were about 8-10 inches long. This should be placed at the top of the reservoir area.

7. Fill the bottom with pea gravel, enough to cover the entire pipe and overflow height. This will be anywhere from 5-10 inches depending on your situation. Other people use sand, but we used gravel.

8. Cover the top of the gravel with a layer of landscape fabric. This prevents the soil you’ll add on top from dropping down into your reservoir bed. You want to keep these two layers separated, so layer it thick enough to keep soil from getting through.

9. Now it's time for the soil layer. We had some pieces of wood from a tree we'd recently cut, so we added this on the very bottom of our soil layer. This is similar to the hugelkultur method of growing. The slow breakdown of the logs nourishes the soil for a longer period of time. Add compost and organic material of any kind to build your planting medium. We collected some worms and threw them in as well.

10. Fill your reservoir and plant!

Materials you’ll need:

Wood for framing

2-3” screws

Mesh screening for bottom

Pond liner

Big-O perforated flexible pipe (or your version of this)

1/2”-1” overflow tube

Gravel or sand

Landscape fabric

Soil/compost/organic material

*Sizes, lengths and quantities will be determined by your design requirements and space

You can see the evolution of our raised beds in the photos above. We added the covered screens after we realized that we had a lot of wildlife exploring our new plants. We built these out of 2x2 wood pieces and chicken wire. They’ve been very helpful for us. You many not need them, so it’s an optional step. If you’d like to know more about how we built these, please reach out. Or please share your own designs. Let’s collaborate!