Unlike traditional single-row gardening where everything in that row is ready to harvest at the same time, with Square Foot Gardening we plan ahead so that we have a continuous harvest of fresh lettuce all the time—never too much or too little. Well, at least until it gets too hot to grow.
Take a look at this Planting Schedule for Continuous Harvest Crops from the All New Square Foot Gardening, 3rd edition book. There are plenty of crops you can grow for a continuous harvest: radishes, beans, spinach. There are also many more found in the book. The example we’re using is lettuce, since it seems to be the most popular crop for planting multiple time throughout the growing season.
Leaf lettuces, as you may know, are grown four per square. As they mature, cut just a couple outer leaves off of each plant with a sharp knife for your daily salad and let the center continue to grow. When it’s done, pull the plants out of that square, add a trowel of blended compost to refresh the nutrients in your Mel’s Mix™, and replant the square with whatever you’d like.
Decoding The Planting Chart
In the chart, the “0” (zero) on the left represents the average last spring frost date and the “0” on the right is your average first fall frost date. If you don’t know the frost dates for your specific location, Google “frost dates by zip code” and you’ll see several sites where you can get this information.
Let’s say you live in Baltimore, Maryland. Your average last frost date in the spring is April 30. Looking on the continuous harvest chart, you’ll notice that you can start planting lettuce seven weeks before the last frost date and three weeks after. In this example, you can plant a single square of lettuce every other week for a total of ten weeks from March 26 through May 21. If you have a large family or really like salads, you can plant a square each week.
If your weather starts to turn hot sooner than expected, you may get an extra week or two out of your lettuce by covering it with shade cloth. Once the weather continuously gets too hot, lettuce turns bitter. When that happens, pull it, add compost and replant that square as described above. But don’t despair, you can pick up planting your fall squares of lettuce in late summer. Of course, this depends on your area’s first frost date. There are some cultivars that are called “heat tolerant” or “slot to bolt,” so be sure to search for varieties if you live in a hot climate.
In our example, Baltimore’s first frost date is October 15. On the chart you’ll see that you can plant leaf lettuce from 11 weeks before the first frost date to 7 weeks before or July 30 through August 27 for a fall harvest.
Protecting Your Harvest From Late Cold Snaps
Remember, because they’re so small, you can easily protect your Square Foot Gardening raised beds from a cold snap by using the dome made from two 10-foot lengths of 1/2” PVC pipe, positioned in the bed as shown and held together at the top with a cable tie.
Then you put the appropriate cloth over it such as plastic garden sheeting, a large bed sheet, or other covering of your choice. Make sure the cloth is large enough to completely cover the bed and overhang it so you can weigh it down with bricks or stones on all four sides.
In both spring/summer and summer/fall, you might lose a square or two because it’s been planted too early or too late, but that’s fine . . . seed is cheap. It’s worth it to try to “push the envelope” a little bit. The rewards usually outweigh the failures.
For More Information
If you love the continuous harvest schedule, check out the All New Square Foot Gardening, 3rd edition book for more. In addition to the Planting Schedule for Continuous Harvest, there are schedules for Spring Indoor Seed-Starting, Outdoor Planting Schedule for Spring and Summer Crops, and Planting Schedule for Fall Crops. It’s available on Amazon at https://amzn.to/39RbMVE.