Square Foot Gardening

By Steve Reiners, Professor and Chair, Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech. This is part of a series of columns that he wrote about vegetable gardening during the pandemic.
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May 11, 2021

Some of you may remember a PBS television program that was popular in the 1980’s called Square Foot Gardening. The host was Mel Batholomew, a retired engineer and enthusiastic gardener. In addition to his TV show, he wrote books on the subject including All New Square Foot Gardening (3rd Edition, Cool Springs Press, 2018).  The basic idea of Square Foot Gardening entirely changes the way you plan and plant your garden.

Most of us tend  to make our gardens look like farmers’ fields, with long single rows and walkways between each row or bed.  Although this setup makes sense for farmers, there might be a better way for gardeners using hand tools to plant that will save space and produce more vegetables per square foot – hence the name.

Farmers set up their fields with long rows because they need to pull equipment with  tractors up and down rows.  They need to mechanically cultivate between rows to control weeds and perform other tasks.  Driving a cultivator through a field is a lot quicker and easier if you are working with a long, straight row, minimizing how often you need to turn around.

But in your garden, it’s a different story. Let’s say you have a 10-foot long bed and it’s three feet wide and you will be planting carrots.  Copying a farmer, you could plant a single row of carrots, spaced 3-inches apart within the row.  You could get as many as 40 carrots from that row.  If you planted a double row on the bed, you might harvest 80 roots. 

Square Foot Gardening tries to maximize production by organizing your garden by each square foot instead of by rows.   To space carrots properly, you’d divide each square foot into a 3 x 3 tick-tack-toe grid and plant a seed in the center of each square.

If you lined up ten of those 1-foot-square, 3 x 3 grids down your 10-foot long bed, you could harvest 90 carrots.

Now deploy those grids three-abreast across the 3-foot-wide bed, and now you’ve got the potential to harvest 270 carrots – nearly 7 times more carrots than planting carrots in a single row.

The same principle works for other garden vegetables by just changing the number of squares within the square foot based on the size and needs of the plant.  This 3 x 3 grid works well for beets, onions, garlic, turnips, peas and spinach.  A 2 x 2 grid is good for bush snap beans, lettuce, endive, Swiss chard, and many leafy greens.  A 1 x 2 grid is fine for cucumbers.

Large plants -- like cabbage, broccoli, cauliflower, peppers and potatoes (both white and sweet) -- will need 1 square foot per plant.  Tomatoes (staked or caged), eggplant, and summer squash should have 2 square feet.  You can pack radishes tightly in a 4 x 4 grid.

One advantage of spacing the plants optimally this way is that they quickly form a canopy and fill up the space where weeds can grow, largely shading them out.  But if you do have some weeds pop up, it can be very tedious to pull those weeds out of the grid by hand.  

Another disadvantage from the plants growing so closely together is that it can encourage plant diseases.  I always tell gardeners one of the most important things to do to minimize plant diseases is to have good air circulation. Spacing plants widely helps them dry out quickly after a heavy dew or rain.  Plants packed into a Square Foot Gardening arrangement will have wet leaves for longer periods – which can promote many plant diseases.

If you use this method, plants will likely need more water and nutrients than those planted traditionally.  Using the example above, in the same area you could have 270 carrots versus 40.  That’s likely going to greatly increase the fertilizer and water your planting will need. 

Whenever you read about Square Foot Gardening, it always goes hand in hand with raised beds.  Just about every picture you see and every website you visit, shows this being done only with a wooden raised bed filled with rich soil.  Typically, the beds are 3 to 4 feet wide and 8 to 12 feet long. I’m sure many people don’t try this method because they already have a great garden and don’t need raised beds.

But there is no reason why you can’t use these spacing principles in your regular garden beds without raised beds to optimize your spacing between plants.  Test it out in a small area this summer and see how it works for you.

In the garden this week

Despite a few warm days, the frequent cool rains have kept our soil temperatures low.  In the Finger Lakes, it’s barely over 50F -- far from ideal for getting any seeds other than peas and spinach to germinate.  You can increase soil temperatures after planting by laying a clear piece of plastic over the row.  One sunny day and soil temperatures can be 5 to 10 degrees higher.  Remove the plastic after seeds start to germinate.