We’ve had some very heavy rains this summer, and it’s reminding us why planting cover crops is so important this fall. Cover crops increase the carbon content of our soils through root growth, root sloughing in response to mowing, and when we incorporate vegetative growth into the soil, directly tilling the plants under or composting first.

Soils with higher carbon content drain better, which prevents flooding and keeps our crops from getting “soggy feet.” Water saturated soils create lots of problems for plant growth – they quickly become oxygen depleted, and plants respond by growing new roots to hunt for oxygen. This root growth is costly – it means the plants aren’t growing the greens or fruits we want. And the new roots generally form at the plant base, on the soil surface, where there’s plenty of oxygen available, while deeper roots may die. The result is shallow-rooted plants that are more susceptible to drought and more vulnerable to wind and other disturbances.

Carbon-rich soils are more resilient to dry conditions as well as wet. In addition to increasing soil porosity and drainage, higher carbon content also lets soils hold more water. Deep rooted grasses like rye are especially good cover crops for increasing the carbon content of the subsoil, so that plants can be scavenging deeper water reserves even when the surface layers have dried out.

Well established cover crops will help prevent our soil from being washed away by winter rains, but they also prevent leaching of soil fertility. Nitrogen and other nutrients still available in the soil after summer and fall crops can’t be leached out of the soil by heavy rains when tied up in cover crops like oats and rye.

We plant quick-growing winter rye in most of our fields. We mix hairy vetch with the rye to add nitrogen to the soil, but only in places where the soil won’t be worked until late spring (vetch sprouts now, but puts on most of its growth in late spring). Where we plan to have early spring crops (like potatoes, peas, and early spring greens), we plant Hulless Oats. Temperatures below 10°F kill our oat cover crops in January here, and the residues are easier to work into the soil for early crops. Red Clover, Crimson Clover, and White Dutch Clover are also good winter cover crops, but are slower to establish than other types – so sow clovers at least 40 days before your average first frost.

Good luck with your cover cropping – it’s one of the most important things you can do to sustainably manage soil fertility.

Useful References from SESE: Our Fall & Winter Quick Guide lists specific varieties best suited to growing in the cooler months.  We also have on our website the Simple Winter Gardening Guide from Brett Grohsgal of Even’ Star Organic Farm and the Fall & Winter Gardening Guide by our own Ken Bezilla.

If you thought it was time to sit back and enjoy the harvest, think again! Growing fall and winter crops means getting out now to get your plants started.

August and early September is the ideal time to start beets, kale, Chinese cabbage, daikons, collards, rutabaga, turnips, and mustard greens. You can also continue to sow carrot, lettuce, cilantro, arugula, and radish successions. We’ll sow spinach in mid-September, when cooler soil temperatures make germination easier. Bush snap beans can be started now, but you may need to protect them from October frosts (we use row cover) to get much of a harvest. It’s too late for all but those in the Deep South or with extended frost-free falls to sow cabbage, broccoli, and Brussels sprouts.

While it may feel too early – and too hot – to be planning for the winter table, the rapid loss of sunshine in fall means we have to give these crops an early start.  Remember, we had our strongest sun already at the solstice in June – fall may feel warm, but it lacks the light intensity of summer.

Hot temperatures are great for quick growth, but some of the best fall crops are difficult to germinate in warm soils.  Young, shallow-rooted plants are also more vulnerable to drying out than older crops with deeper, more established root systems.  Remember to water frequently – germinating seeds may require watering twice daily, or more.

One trick we use is to start kale, collards, and other transplant crops in closely spaced nursery rows in beds with some afternoon shade. We also like to use beds that are shaded by tomatoes and pole beans – plants that will be gone in a few months, just when we start needing all the light we can get on our fall crops.

For over-wintering crops, shade from nearby deciduous trees helps keep seedlings moist, and in the winter and early spring the same beds will get plenty of light.

It may be a struggle to get seeds to germinate in summer heat.  Be patient!  Wait for the break in the hot weather – it’ll come soon, we promise.  And remember there are some benefits – even the weeds are struggling to come up!

Lettuce, spinach and cilantro need cool temperatures to germinate. Start them indoors – or in the refrigerator! Pam Dawling at Twin Oaks sows nursery rows of lettuce on summer evenings outdoors under shade cloth, waters well and covers with an inch or so of crushed ice.