Late Cover Crops

Cover CropsI’ve been called out for not recommending the planting of cover crops earlier in this blog. Okay, guilty! Cover crops, especially legumes, are best planted a couple weeks ahead of the first killing frost — as if our changing weather patterns give us any clue as to when that’s going to happen — to give them time to germinate. Legumes usually take longer to germinate. But if you haven’t planted? Experience tells us it’s not too late, depending on your climate and the precautions you take.

Grasses — ryegrass, winter rye, winter wheat and wheat grass, oats — germinate more quickly and there fore are more suitable for late planting. But some legumes — hairy vetch for example — are more adaptable to cold climates and will germinate if planted late, especially if you get a string of warm days in the late season. Buckwheat is a good grass choice for colder climates. Not only does it germinate more quickly than legumes, it’s a quick grower.

Both legumes and grasses will germinate under cover of mulch if the mulch isn’t spread too deeply. And the mulch will help protect young spouts from cold damage — a must if planted this late — as well as give them a boost in the spring. Here’s a chart (PDF format) of best cover crops for different areas of the country.

Why plant cover crops at all? Cover crops are one of the oldest and most efficient ways of improving your soil. They don’t call it “green manure” for nothing.

  • They increase soil organic matter
  • Legume cover crops replace nitrogen in the soil
  • They improve soil porosity
  • They help soil aeration
  • The prevent erosion
  • They attract and protect earthworms
  • The increase “channels” for future row crop roots to follow
  • They reduce compaction
  • They increase nutrient recycling
  • They help interrupt the cycle of soil-borne diseases that attack vegetables

Cover crops are also a big part of no-till gardening practice.

Planting late season cover crops requires more than choosing the right crop. Watch the weather. When you have a string of warmer days predicted, go ahead and plant. Prepare the soil like you would for any other crop by tilling to a depth of six inches or so. Broadcast seed as recommended. Rake into the soil, water, if necessary and stand back. Patience is a must. Even if your cover crop doesn’t germinate (or germinates unevenly) there’s a good chance it will come up in the spring, especially if mulched. There’s nothing like seeing your garden turn green during spring’s first days, well before it’s time to plant. Turn your crop into the soil as early as possible. Don’t let it go to seed. Let it stand for a week or two — or more! — before planting. And next year? Resolve to do it earlier!

More on cover crops here.