Take care of the soil and it will take care of you. Cover cropping is an easy way to condition the soil whenever a part of your garden is lying fallow. Cover crops protect the soil, build structure to maintain the microbial life within, suppress weeds, add organic matter and keep nutrients from leaching away each time it rains. Some popular summer covers include: buckwheat, sudan grass, sunn hemp, cowpeas, and velvet beans. Each one has its particular benefits, so choose according to your needs. (Here is a comprehensive guide to cover crops of the southeast.)
Some summer covers we’ll be using on LSSI are buckwheat and velvet bean. Buckwheat is a quick-growing cover crop for short sowing windows. I recently spread some buckwheat seed where I intend to plant sweet potatoes next month. I cleared the field of winter arugula, but my potato starts were not ready yet. Come June, the buckwheat will have grown shin-high and will be easy to hoe in to make way for my sweet potato seedlings. You can put buckwheat in for longer, just keep trimming the heads back with some hedge shears or a weed whacker each time it flowers so it won’t reseed itself. I’ll be seeding buckwheat all season as my earlier spring crops of lettuce and beans quit producing and it’s too hot to plant a second round of snap beans or summer squash.
We’ll grow velvet beans in the raised beds that need a break this summer. Giving the soil regular rest is a sound practice in sustainable soil management. On LSSI, we rotate our production beds, trying to give each bed or row a rest once a year. Think of cover crops as a living mulch, and velvet beans lay it on heavy. It grows a lot of organic matter, and because it is a legume, it will fix nitrogen into the soil for the next crop. Just chop it in with a hoe and let it sit and break down before sowing the next thing. Velvet bean is an especially beneficial cover for us because it is known for deterring the detrimental soil pest, the root-knot nematode. We haven’t grown regular tomatoes in our garden for years because this critter binds to the roots and takes soil nutrients from our plants. Look out for an update next summer, as I plant tomatoes in the beds I treated with velvet beans to see its effectiveness in managing that pest.
And since, we’re talking ‘maters, I want to share this great cover cropping tip for you to experiment with next spring, but in order to do it, you’ll get started late this fall by scattering rye seed. Our cherry tomato and eggplant beds will be nearly weed-free this summer because I sowed this rye last November and let it grow winter-long in order to plant my nightshades into this spring. I simply cut the rye at soil level and turned the soil where I wanted to transplant my seedlings. I turned it a few weeks in advance. That’s important or else they’ll compete with the rye and won’t get a good growing start. The summer heat will kill the rye and I’ll essentially have grown my mulch in place.
As soil biologist Elaine Ingham reminds, “Nature abhors bare soil.” If you’re going to leave it bare, she’ll put something in there that you will probably call a weed. Spread cover seed.
Another reminder for the more northerly growers in clay-rich soil: Use daikon radish, AKA nature’s plow, to break up that clay. Sow this fall and let it over-winter and rot in the ground.