Installing our Square Foot Garden Boxes


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Installing our SFG boxesOur plans are coming along nicely now. The boxes are built, the garden is cleared and most importantly… our Sphagnum Peat Moss has finally arrived – We can mix our perfect soil (Mel’s Mix) at last. After yesterdays little escapades in the garden (digging, cutting and clearing the garden), I’m not too enthusiastic about the idea of more ‘hard labour’ today but I am impatient to get our Square Foot Garden boxes installed, the soil mixed and the boxes filled. I’m like a kid in a candy store and I just want more… now! After visualising it all on paper I can finally get to see what the boxes look like in reality. Oh well, time to get cracking then.

Laying out the boxes

First step was to lay the boxes out and mark the edges in the ground. Then out with the spade to cut away some of the lawn where the boxes stuck out further than the previous flower beds did. I saved the squares of grass sod that I cut out with the spade for the first layer of our soon-to-be compost heap. I also had to level the ground under two of the box positions so that we don’t have slanted boxes, we want any heavy rains to soak through the soil, not run off and wash away our Mel’s Mix.

After making sure that everything was level we positioned the boxes and placed a layer of flattened cardboard boxes in the bottom to act as a weed barrier and to prevent anything else from growing or crawling up into our boxes from the ground below. A layer of newspaper on top of that just for good measure and a good watering to get the paper and cardboard all soggy and well tucked into the corners for a good seal.

Time to mix the soil and fill the boxes

A quick bit of advice here – Don’t mix your Mel’s Mix outdoors on a windy day! The Peat Moss is really light and fluffy and will get up your nose in even the slightest breeze. Preferably wear a mask of some sort in any case.

I found an easy method of measuring the equal quantities of Sphagnum Peat Moss, Vermiculite and compost required for the Mel’s Mix. The compost generally comes in 30dm3 (cubic decimeters) bags which is the equivalent of 30 liters, the vermiculite was in 2 kg bags and the peat moss in 6 cubic foot bales. All I did was to find a 25 liter bucket and measured out everything in that to get equal volumes. The peat moss bales are compressed 2:1 so, as we were shoveling it into the bucket, we were sifting it through our fingers to ‘fluff it up’ again first. What a lovely texture it is, almost like handling shredded silk 🙂

We mixed our Mel’s Mix on an old tent groundsheet that we discovered lurking in the garage, rolling the mixture back and forth inside the groundsheet a few times and then making sure it was well mixed by spreading it out as thinly as possible by hand before rolling it once or twice more. I have to say that I’m not overly impressed with some of the compost that we bought. The quality varied immensely and some of it was just plain bad! We sifted out all the bad clumps (compost that is not well matured tends to be soggy, clumps together and stinks) and added a bit more of the better stuff until we were happy with the result.

As a side note: I spent three of my school going years at an agricultural college and have since spent quite a bit of time during the past 20 odd years pottering around in various gardens around South Africa but I have never seen soil that looks quite like this. Not even the best quality ‘potting soil’ I have seen comes anywhere close to it.

We mixed the soil in small batches so as not to strain our backs too much in the process and then dragged the groundsheet over to the boxes and simply tipped it in. Once the boxes were full we gave them a good watering to help the soil ‘settle’ before topping up the boxes to the brim. Remember that we are using boxes that are 8 inches deep (20cm) instead of the 6 inches that is usually recommended, so two 2×1 meter boxes and one 1×1 meter box works out to exactly 1 cubic meter of soil.

Attaching the Grids

The last step was to attach the square foot grids to the top of the boxes. I know that many people simply use string or thin nylon rope for this but we wanted more permanent (and better looking) grids on our boxes that, even when the boxes are filled with bushy plants, will still clearly demarcate the squares. So, wooden slat grids they are, screwed to the top of the boxes.

So what do you think of the results? (click on the images to enlarge):

Yep, we’re pretty impressed too 🙂

Happy gardening


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5 Comments on “Installing our Square Foot Garden Boxes”

  1. Jenni Pestana says:

    Wonderful site you have here. I am into my 2nd year of SFG and it is great to read your story. Very neat boxes you have built. I did not bother to get Sphagnum Peat Moss, but used the compressed blocks of coconut peat. I also was lucky enough to have my own vermicompost to add to the mix. Good luck with your veges.

  2. Venessa says:

    Would like to see what your SFG looks like now.

  3. Johan says:

    Hi what is the actual sizes and how deep is the sfg boxes? how do i get involved

    • Mark says:

      Hi Johan

      The sizes and shapes of the boxes are up to you. We do not recommend the boxes being wider than 1.2m though. You still need to be able to reach into the middle of the box from both sides comfortably without climbing into it and compacting the soil.

      Also remember tha any box longer than 3m will be too tempting to try and “hop” across it instead of walking around it. This can also be disastrous if you miss and fall into the bed and crush your plants.

      How to get involved? Well you could start by just going out into your garden and observing it for a while. Try and picture where you would place your boxes according to where the best sun is, where no water puddles during heavy rains and where it is convenient to access. Now picture the size of the box/es and half the planning is done. Then attend one of our Square Foot Gardening Workshops in person or download our online course (coming soon).

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