Backyard Garden: Box Construction

As I mentioned yesterday, I said I would be back to show you the construction of my garden boxes. Between building the boxes, and filling them with dirt it took less than 2 hours. There are many variations to these boxes. My goal was quick and easy and not necessarily pretty or well built. These instructions reflect that as this is what has worked for me. Feel free to get creative and come up with your own variation. Gardener's Supply Company carries a line of prefabricated boxes that require minimal assembly. You really can't go wrong with these boxes.

The number of boxes you build is up to you and how much food you need. 1 box = enough food for 1 person by producing just the basics. For a full range of produce count on 2-3 boxes a person if you have the space.


Boxes: 4 - 1”x12” pieces of untreated wood cut in 4’ lengths
12 eyelet screws
50+ feet of string
4-8 corner brackets
Nails or deck screws
Weed barrier – 4’ width

Soil: ~3 cubic feet peat moss (usually 1 large bag)
~3 cubic feet compost (2-3 bags of variety)
~3 cubic feet expanded shale (1 40lb. bag)

Tools: Hammer or cordless screw driver (depends on use of nails or screws)
Staples & staple gun (if you have one)
Ruler or yard stick
Optional: work gloves, shovel, tarp

Notes about the supplies:

1. If you don’t have a saw the 4’ lengths can typically be sawed in the store OR in some cases, may be sold in that length already.

2. Purchasing untreated wood is imperative. Treated wood will leach chemicals into the soil that will then end up in your produce.

3. The number of corner brackets varies. You want at least four for each corner if they are heavy duty or you can use eight smaller ones by utilizing two in each corner. There is not a particular bracket to use as long as it holds the boxes together. The boxes will not be moving once you put them in place so the main purpose is to keep the wood together so the dirt doesn’t fall out. Meaning: don’t over think it.

4. Creating a fresh soil bed is important because you want to provide a nutrient rich base as well as eliminate the possibility of weeds sprouting. The general rule of a green thumb when it comes to mixing your own soil is 1/3 peat moss, 1/3 compost, 1/3 expanded shale. This provides the best ratio of nutrients, fluffiness, and moisture retention. You can use premixed soil from a garden center, but I wouldn’t recommend it being your only ingredient. I actually used some in my mix because I needed the extra volume for plants such as tomatoes. I’ll talk more about the soil in the instructions section below.

5. Peat moss, expanded shale, and compost can be purchased from most garden centers. The key to buying compost is to get a variety. You don’t want it all from one source unless it’s your own. Check your local municipalities as well. Many times they have a compost/garden program and you can get these materials for free.


1. Find a flat surface to put your boxes together. It usually helps to have a second person when doing this. One person can concentrate on holding the bracket and using the tool, while the other person holds the wood in place. Hammer or screw your brackets by alternating each corner to ensure you end up with a square box. Placing the brackets on the inside or outside of the box is personal preference. Mine are on the inside.

2. Now that your boxes are together the next step is to secure the weed barrier to the bottom of the box. There is no right or wrong bottom so choose either side. Since you purchased the weed barrier with a 4’ width you won’t have to worry about layering it. It should fit nicely across the entire box. Cut the length to match the box. You can either staple this to the bottom of the box or use small wide-head nails. Be sure to pull it taut to minimize gapping.

3. Once your box is complete, move it to its end location. Be sure the location you choose has plenty of sunlight.

4. It’s time to mix the soil recipe. This can be done directly in the box (which is why it’s important to move it to the end location beforehand) or you can spread out a tarp to do the mixing. You want to fill the box at least half way up the 1”x12.” You should have purchased enough ingredients, however, if you feel you need more don’t hesitate to add more. Again, there is no right or wrong amount. If you plan on growing tomatoes, carrots, potatoes or any other vegetable that grows in size below the surface or has deep roots, you will want deeper soil. Remember, plants will not be able to root into the ground you’ve placed the box on because of the weed barrier. The purpose of the weed barrier is to obviously keep weeds and grass from growing in your box. So you have to create enough depth for the plants you want to grow. The key thing to remember is the ratio. You want a 1/3 of every ingredient. You may feel like you are using a lot (like the shale) but once you get it all mixed up it will be just right. Stick to the ratio. Once you have all the ingredients on the tarp or in the box mix them all together using a shovel or your hands. The peat moss has a tendency to be dusty. You can add a little water to help control this. If using the tarp, dump or shovel the new mix into your box.

5. Almost done. Now it’s time to lay out the grid for easy planting. I have seen wood slats used before but I went for a cheaper route (eyelets and string) that works just as well. Screw in three eyelets on the top of each side (see the picture above). The eyelets should be about 1 foot apart. Take the string and run it through each eyelet to create a 1’x1’ grid over the top of your box (see picture). Tie off each end.

Finished! Now it’s time to plan your garden so you can start planting. I’ll be back soon to show you how easy it is.

One final note. I have cats that love to be let out in the backyard. I also have rabbits in the neighborhood. I don't want either one to enjoy my boxes more than me. The easiest solution is a simple netting that can be purchased to cover the boxes. I picked up some netting used for fruit trees and cut it a few sizes larger than my boxes. I can water right over the top of it and it can be pulled back easily for planting. 


Square Foot Gardening
Gardener's Supply Company

PDF instructions here

images: indigo 26