Square Foot Gardening How-To: Part 2

Sorry this post is a day late, everyone. I wasn't feeling well yesterday and was stuck in bed. Anyhow, better late than never, right?

I hope you all have decided on a location and design for your square foot garden and are ready to get building! For more info on designing your garden, see my How-To: Part 1 here. Also, if you haven't gotten Mel's book on square foot gardening, I highly recommend it. It's a must have on this topic.

 For Part 2 we will discuss an overview of building your garden boxes, their grids, cages, and supports for your growing veggies.

Step 1: Building your square foot boxes

I had my husband, Zack, write this part because.....well, I know nothing about building stuff (thanks honey!)

If you want to follow Mel’s instructions to a t, I highly recommend getting his book.  But for a quick synopsis, here is what I did.  Mel recommends using 2x6 boards for the box so you can maintain a 6” deep soil fairly easily (yes, that really all you need! Only 6" of soil depth!).  I used 2x12 so we could have a little more freedom to make the soil as deep as we like because we are growing veggies like carrots, onions, and garlic that are going to grow down instead of up on top of the soil.  So for one box just get two 8 foot long boards of whatever width you prefer, and cut them both in half so you have 4 boards, each being 4 feet long.  To arrange them into a square, use the stagger method of aligning the ends together.  Each board will have only one end exposed, and this ensures the dimensions are equal all the way around your square.  They can be screwed together using deck screws.  Three to each joint should be plenty.

This should leave a box shape and next you can decide if you want it to sit on the ground or raise it up.  If you choose to let it rest on top of the ground, you are ready to get started with your soil.  If you would rather place the box on supports like we did, then putting a floor on the box is fairly simple.  The interior of the box is 48” square, but the surface area to cover with a floor is 50” square.  A lot of times people don’t realize that the sizing of boards is not actually what they say it is.  So a 2x4 isn't actually 2 inches by 4 inches- it’s a bit smaller.  To cover this box you will need five 2x10 boards cut 50 inches long.  Notice, however, this does not add up to a full 50 inches; there is a huge gap in the floor.  So a 2x4 at 50 inches long will cover the gap that is left over perfectly.  I used three deck screws on each end of the 2x10’s to attach them, and along the side I spaced the screws about six inches apart.  

Now that the floor is on the box, you will need to add drain holes so the box allows excess water to exit.  With a ¼” drill bit, drill holes in your floor spaced about a foot or less apart in each direction, and in the corners double up on the holes.  You should end up with about 20 holes spaced fairly evenly.

Now the box is ready to be fliped over.  Do this with a partner because it will be really heavy at this point.  Cinder blocks are inexpensive and perfect for supporting the box.  Select a level surface where you would like it to sit (you need to be confident about where you want it to go because once the soil is in it, the box is pretty much impossible to move) and place the box on them.  One under each corner will do just fine.  Take a minute to relax and give yourself a pat on the back, then you are ready to fill your box with Mel's mix and build your grid for the top of the box.

Step 2: Mel's mix

My very first post about my garden talks a little about Mel's mix. It's like gold when it comes to gardening.

Mel's mix:

• 1/3 peat moss
• 1/3 blended compost
• 1/3 oil dry

But the 3.9 cubic foot bales of peat moss. It is much more cost effective than buying several of the smaller bags. As for the compost, try to get several types of compost at your local garden center (or even better, use  your own homemade compost!). Lastly, Mel will tell you to use Vermiculite, not oil dry, in your Mel's mix. Don't do that! Oil dry is significantly less expensive. You can find it at most auto parts stores. 

I know what you're thinking now- I'll just use some of my existing soil to fill my box up and save some money. DON'T DO THAT EITHER! Your existing soil will not have all the nutrients your growing plants will need and it probably has weeds and doesn't drain well. The whole point of using Mel's mix is to avoid having to use any fertilizer, eliminate weeds, and provide an optimal water balance for your plants. Believe me, it's worth spending the money on the peat moss, compost, and oil dry. 

So, how much Mel's mix will you need? That depends on how many boxes you have, but I'll use one 4x4 box as an example (which is what our box is). A 4x4 box that is 6 inches deep has a volume of 8 cubic feet (4 x 4= 16, then divide by 2 because your box is only 1/2 a foot deep, 16/2= 8 cubic feet). Since there are 3 ingredients that you need, we just accounted for 9 cubic feet; 3 cubic feet of each ingredient. We were able to do this because our 4x4 box is about 10 inches deep. If you have a true 6 inch deep box, you'll have to adjust a little. 

Since the peat moss already comes in 3.9 cubic feet compressed bales (which equals about 8 cubic feet lose), you'll only need to use a little less than half of one of them. We used about 3 or 4 bags of compost, and one 40 lb bag of oil dry. These ratios are not exact, but they don't have to be so don't stress about it. The most important thing is to have an adequate amount and variety of compost.

Once you have all your ingredients, you are ready to put them in your box, mix them well, and add you grid. 

Step 3: Make your grid

These next sections were written by me, so please forgive me if they aren't perfect :)

Your garden box absolutely must have a grid on top dividing it into 1 square foot sections. The grid should be prominent and permanent to your box. 

The material Mel recommends using when building your grid is wood lath. This can be found at home improvement stores and is already cut to 4 feet long. And it's cheap which is always good. 

You will need 6 strips of wood, fairly narrow but still sturdy. You don't want them to be too wide or they will take up too much of your gardening area in your soil. Depending on how deep your boxes are, the grid can either rest right on top of the soil or span the width of the box and kind on hover over the soil (like ours does). Be sure to check out the pictures at the end of this post to get a better idea of what I mean. 

Now all that has to be done is to measure and mark off 1 foot increments on one side of your box. Do the same to a side that is perpendicular to the first side you measured, lay your wood lath strips out at the marks you measured, and screw the boards down to your box. You will also want to drill a hole at each intersection and connect the wood lath with some type of hardware. We just used more screws but you could also use a nut and bolt if that's what you have. 

Now your box is ready to plant. I'll talk more about planting in Square Food Gardening How-To: Part 3. Look for that at the beginning of next week!

Bonus steps: Cages and supports

I'm just going to very broadly discuss cages and supports for your square foot garden. Check out Mel's book for more detailed instructions. 

Cages are used to protect your garden from weather or pests. It will need to fit over your entire box, what ever size that is. Using plastic coated wire fencing, you can make U-frames and cover them with plastic or chicken wire, depending on what you want to protect your plants from.

For supports (to use with climbing vegetables like tomatoes, beans, peas, etc), Mel recommends steel tubular pipes which are strong and pretty inexpensive. Nylon netting can be attached to the steel frame to give support to your growing vegetables. The frame can either be driven into the ground or attached to the box itself. 

Also, keep in mind that your support for climbing veggies will potentially shade other vegetables in your box. For this reason, keep frames on the north side of your square foot garden box. 

An update on our square foot garden:

All our plants are doing just great! They are going so fast! We water about every other day and that's it. There is no other care involved right now. We are keeping an eye out for weeds that may be gotten blow onto the top of our box by the wind, but we've only found 2 or 3, and they are easily removed. 

This is a great picture of the grid on top of our box.

Here you can see how tall our onions are getting!

2/19/13

3/06/13

Our peas are also getting big!

   

3/06/13

The most exciting thing we've noticed is that our spinach plants have itty bitty spinach leaves on them!

You can see the little spinach leaves there in the middle! So cool!

I hope this post was helpful and you enjoyed it! Check back at the beginning of next week for Part 3 which will discuss the fun part of gardening: choosing you plants and planting!