It’s September, and much of the garden has been put to bed. As we approach the autumnal equinox, daylight hours begin to recede noticeably. Sunflower heads have been cut for drying, tomatoes have been picked green and brought indoors, and pumpkin fruits sit bright and orange while the rest of the plants have succumbed to mildew and the season’s end.
Now is the time to plant legumes as cover crops, though. Members of the pea and bean family germinate well in the cooler soil of autumn. Plants like clover, fava beans, vetch, and winter field peas are perfectly cold hardy, and will continue growing (slowly), well into winter, and often into the following spring. As they grow, they work with naturally occurring soil bacteria to draw nitrogen from the atmosphere and fix it in nodes along their roots. So much nitrogen is accumulated in the soil that any crop planted in the same spot the following spring will have a natural advantage, and accelerated foliar growth.
So if there is a patch of soil in the garden that would otherwise sit empty until next spring, consider planting one of the following useful cover crops to take advantage of this organic growing method.
Crimson Clover – Hardy to Zone 6: -23°C (-10F). Tilled plants break down in just ten days, ready for spring planting.
White Dutch Clover – Hardy to Zone 4: -34°C (-30°F). Allow two weeks for this clover to break down prior to planting.
Hairy Vetch – Hardy to Zone 4: -34°C (-30°F). Its deep roots help to break up compacted soil as it fixes nitrogen for spring planting.
Fava Beans – Hardy to Zone 7: -17°C (0°F). Plant in the heaviest of soils, and plant as late as November on the coast. This plant ignores winter and chugs along producing lots of carbon-rich foliage to compost, and fixing nitrogen as it grows. In the spring, just cut the plants down at ground level and lay them as a mulch over spring beds.
Winter Field Peas – Hardy to Zone 6: -23°C (-10°F). Easy to plant, easy to till under the following spring. Your soil will thank you for it.
All of these cover crops produce organic matter that will feed garden soil over the following spring and summer, and the nitrogen they fix will improve growth for all crops that follow.