You’ve dug all the potatoes, harvested the onions and garlic, and now have open spaces in your outdoor garden. With first frost still two to three months away, there’s plenty of time to grow a second crop in these unused areas. But what’s best to grow? And when and where should you start the new plants?
Lettuce, spinach, arugula, chard, kale, broccolini, and other leafy greens are good choices for a second crop. Here in Rhode Island, they can be grown and harvested outdoors right up until Thanksgiving (the fourth Thursday in November). Start the seeds in trays in your greenhouse, and as soon as they develop two true leaves (not cotyledons), set the young plants in the ground outside. Growing a second crop in pots in the greenhouse isn’t always as successful because the greenhouse warmth can cause them to go to seed rather quickly. My preference is to keep just a few plants in pots that can be moved into the greenhouse before frost and set the remainder in the outdoor garden. Slower–growing plants that can stand a light frost, such as kale and chard, can even be sown directly into the garden soil. Then, by covering these plants with a glass cloche or a plastic hoop enclosure, they can last until Christmas and often beyond if the severest of winter cold doesn’t arrive unexpectedly early.
However, it’s said that greens in the brassica family, such as kale and chard, shouldn’t be grown where you’ve just removed alliums like onions or garlic. So in these areas,you might be better off growing beets or carrots, both of which take 80 to 100 days to mature to harvestable size. Being root crops, they can be left in the ground until heavier frosts arrive, which is often around November in Rhode Island. I usually cover them with a glass cloche to help keep them warmer on cold nights. But a small plastic hoop–style mini-greenhouse might do just as well.
If you don’t plan to extend your growing season with new crops, you might want to sow a cover crop in your outdoor beds, such as winter rye or clover, to help prevent winter rains from leaching nutrients out of the bare soil. Then in spring, this winter cover crop is dug in (my back aches just thinking about that job!) in order to add nutrients to the soil for whatever summertime crops you grow. If you don’t want to sow a cover crop, covering the bed with a clear plastic film will not only reduce nutrient leaching. It will also cook any seeds near the surface and help reduce weeding next summer. Ideally, the film should be removed a few weeks before spring seeding to allow rain to sufficiently moisten the soil. Digging the bed over after removing the film is not recommended because doing so will bring more weed seeds to the surface, making all your careful cooking of seeds for naught!