• Start now, and your cover crop should be the right size before freeze-up
By Carey Restino
My friend recently put in a new garden; a huge, 2,000-square foot expanse of fresh soil in the way only Alaska soil can be fresh — chickweed and nettles springing up between root wads. You can almost hear it screaming for lime as you walk over it.
Since he didn’t have much time this season to do more than throw some manure around, my friend wondered what he could do to encourage better soil and get a jump on next year’s season. Getting his hands on that much compost was out of the question, as it is for most of us who guard our small pile of hard-won compost for our most needy plants.
The answer was clear – cover crops. The idea of a cover crop is beautiful. You plant something that would otherwise be a weed — clover, for example, and then turn the plant into the soil before it goes to seed. The plants add wonderful things to the soil, depending on what you choose and act as a green manure of sorts, enriching the land and encouraging all the good activity in your soil that you want for healthy, thriving plants in the coming year.
If you jump on it, a cover crop planted now will germinate and grow to just about the right size before freeze-up.
Cover crops don’t take a lot of work to plant. Throw some seed around, rake it in if you need to protect the seed from birds, and if your soil is really dry, water. When the plants get to the flowering stage, but before they set seed, mow them and till them in or turn them over right into the soil so the green plants decompose into your garden, enriching the soil, and in the case of some cover crops, fixing nitrogen levels.
While a large garden created in the fall is a perfect opportunity for a cover crop, you can also weave them into your succession plantings in your garden once you get the hang of it.
After your first plot of lettuce is harvested, planting a block of field peas and oats can reinvigorate the soil. Some people have even experimented with planting cover crops underneath other plants, such as corn, though the danger of increasing moisture content in our easy-to-mold area is a concern.
While a few cover crops, such as clover, are available locally, a much wider selection is available online. Armed with a soil test to tell you what your soil needs are, you can select from a wide variety.
Rye is a good contender for our cool falls, but must be carefully watched to make sure it doesn’t go to seed, or you will be pulling it out of your carrot patch for years to come. You can sow it in early fall and it will germinate, be dormant through the winter and begin growing again in the spring, according to my readings. Field peas and oats fix nitrogen and add to your soil’s loam.
Clover fixes nitrogen and helps build rich soils and germinates quickly. Others include sorghum-sungrass and buckwheat. Johnny’s Selected Seeds as well as other seed companies have a complete list of cover crops available and lots of information on the soil-enriching properties of each.
Cover crops can also serve to loosen compacted soil, especially if you have a new garden like my friend’s, which was recently run over by large machinery. Since the ground will be covered, weeds will be suppressed by your cover crop and once the crop is turned into your soil, it will increase the amount of organic matter in your ground. Cover crops also raise the pH of acidic soil — pretty much a given in this state.
Since temperatures are starting to drop — one friend reported a frost up on Skyline last week, sending his cyber-world friends into a tizzy — it might be a good idea to lay some plastic over the ground where you are seeding a cover crop to warm the soil and speed germination. Take it off once the crop has sprouted.
Another word to the wise: consider using a gentle method to turn your cover crop over rather than renting the biggest tiller you can buy and going for it. With new soil, every worm is precious and using a broadfork or other means for turning over your soil is highly recommended if possible. While it’s very satisfying to see the cleanly tilled soil, everyone who has dug into a pile of compost knows that lightly disturbed soil is happiest.
It’s not a bad idea to vary your cover crops from season to season, experimenting with different ones to see what works best and adding variety to your soil.
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