On 18 March 2015, I wrote Intercropping: Companion Planting that Really Works. In that post I talked about planting spinach with peas, and chard with lettuce or scallions. Here I’ll write about vegetable crop combinations that work well for later spring and early summer plantings. In the near future I‘ll write about undersowing winter cover crops in summer vegetable crops.
Interplanting, or relay planting, is a version of companion planting where the second crop is planted while the first is still growing. Lettuce can be interplanted with a slower crop to increase the productivity of an area and provide better habitat for one or both crops. Cultivation is reduced, and the relay planting allows maximum use of the space. Examples include sowing or transplanting warm-weather crops such as peanuts, tomatoes or peppers into the center of beds of lettuce at the transplanting stage, or one month or more after direct seeding.
We have had great results sowing a row of peanuts in the middle of a lettuce bed. The timing is a little tricky, so try it at least twice before deciding whether it suits you. We are still fine-tuning this one! We sow the peanuts April 29–May 12 (around our average last frost date) into the middle of the bed with lettuce transplanted on April 22–May 15. The ideal seems to be to plant regular size lettuce transplants (not overgrown ones!) on the same day you sow the peanuts, or up to two weeks later. We use romaine lettuces and small Bibbs for these plantings, not large spreading leaf lettuces. Back when we sowed peanuts in an empty bed, the slowly emerging peanuts got lost in weeds and the slow-growing unusual seedlings were hard for some of our newer crew to distinguish from the weeds.
We hoe our lettuce beds to kill the weeds, and as long as we remember that the peanuts are there and don’t hoe them off, they do well. In hot springs we have had shadecloth over the whole bed for the lettuce, and the peanuts come up very nicely. In cooler springs we use rowcover. The lettuce grows faster in cooler, wetter springs than peanuts do, so if necessary, we harvest the inner rows of lettuce a bit earlier than we might have expected, before the peanuts get swamped. All the lettuces are harvested before the peanuts grow large, leaving the peanut canopy to fill out the space.
If you’ve done research into whether companion planting works or not, you’ll have found that it’s usual that the yield of one or both crops is lower than it would be if it were grown alone. From my experience I can say that lettuce and peanuts do well together. I’ve read research that has shown that interplanting of transplanted lettuces and tomatoes does not delay the date of first tomato harvest, or reduce lettuce yields. But lettuce sown immediately before tomatoes are transplanted will have a significantly lower yield, as the tiny lettuce seedlings cannot compete with the fast-growing tomatoes. The timing is critical.
Usually we transplant our okra, sowing on April 15, using soil blocks or Winstrip 50-cell flats. Okra grows slowly until hot weather arrives. We sometimes take advantage of this and its upright growth habit to transplant it into a bed of early cabbage. We transplant cabbage in two rows along a 4' (1.2 m) bed on March 10 and the okra in a single row down the middle on May 11. At first the cabbages are relatively small and the okra uses open space in the middle of the bed. As the plants grow, we remove any outer leaves of the cabbage that might overshadow the okra. Finally, in late May and early June, we harvest the cabbage and leave the okra to grow to full size. This method saves space and efficiently uses our time to help two crops with one weeding.
I have read of intercropping cucumbers and okra, giving each plant 3 ft2 (0.3 m2). Again, this uses the very different growth habits of sprawled cucumbers and tall okra to get more crops from the same piece of land. Good soil fertility is needed if the two crops are not to stunt each other.
Some say interplanting corn with big vining squashes deters raccoons and other critters, but I think it deters crew too! If you are interested in Three Sisters Planting (dry corm, winter squash and pole beans for drying) see the Southern Exposure Seed Exchange Guide and Carol Deppe’s book The Resilient Gardener.
Some of this material is excerpted from my book Sustainable Market Farming.
Pam Dawling manages the vegetable gardens at Twin Oaks Community in central Virginia. She often presents workshops at MEN Fairs. Pam also writes for Growing for Market magazine. Her book, Sustainable Market Farming: Intensive Vegetable Production on a Few Acres, is available at Sustainable Market Farming, Pam's blog is on her website and also on Sustainable Market Farming Facebook.
Photos by Wren Vile (lettuce), Kathryn Simmons (okra)