Published on August 13th, 2013 | by gatsbyadmin0
Improve Your Soil Through the Winter… Plant a Fall Cover Crop
Here in Denver, it’s barely the middle of August and we’ve been noticing more and more trees in the early stages of the fall color change before winter inevitably arrives in just a few short months. Summer is winding down, and, sadly, so is the (outdoor) gardening season. So, as you’re harvesting the last of your summer veggies and clearing the beds of plant debris, start considering one last round of planting of some fall cover crops, while the weather is still warm enough, to protect your soil all through the winter.
Cover crops, such as fall rye, crimson clover, buckwheat and others are relatively easy to grow. When they are digested by soil microorganisms they restore organic matter and nutrient levels in the soil. Because they are sown thickly, they also help to outcompete weeds. Cover crops also control erosion from heavy winter rains, and help prevent the soil from compacting over winter. Also, depending on where you live, during the coldest months, the cover crops may actually die, but the soil will still benefit from the crop residue in the spring.
The time is now – to plant cover crops, sow seeds at least 30 days before the first expected fall frost date in your growing region. For cover crops that are only marginally hardy in your area, push back the sowing date to 60 days before the first frost. The more established a cover crop is before winter the more likely it will overwinter successfully.
Here are some common cover crops you can find at your local nursery, Home Depot, etc.
These nitrogen-fixing crops provide a fertilizer as well as organic matter. Planted in fall, they grow slowly until late winter when growth speeds up. Legume crops may not mature until May in some regions. Cut down these cover crops in spring before they go to flower, then till them under.
Hairy vetch (Vicia villosa): Grows to 2 feet high; hardy to -15° F. Hairy vetch is considered the hardiest annual legume. Vetch tolerates poor soil, and matures late. Sow 1 to 2 pounds per 1,000 square feet.
Field pea (Pisum arvense and P. sativus): Grows 6 inches to several feet tall. Field peas are hardy to 10 to 20°F. ‘Austrian Winter’ pea is low growing and late maturing. ‘Magnus’ grows to 5 feet. Sow 2 to 4 pounds per 1,000 square feet.
Berseem clover (Trifolium alexandrinum): Grows 1 to 2 feet high. Berseem clover is hardy to 20° F. Produces high amounts of nitrogen. Sow 2 pounds per 1,000 square feet.
Crimson clover (T. incarnatum): Grows 18 inches high, and is hardy to 10° F. Crimson clover matures late and fixes less nitrogen than other clovers. Sow 1/2 to 2 pounds per 1,000 square feet. If allowed to go to seed, Crimson clover can become an invasive weed.
Cover crops from the grass family grow quickly, tolerate cold, and improve the structure of compacted soils. Thickly sown grasses add increased organic matter in comparison to legumes. Grasses also control erosion which is a real benefit in wet regions. Grasses do not have the benefit of fixing nitrogen as legumes do. Annual grass cover crops are cut down or mowed in spring before seeds set, and then tilled under.
Annual ryegrass (Lolium multiflorum): Grows 2 to 3 feet high; hardy to -20° F. Fast growing and tolerates flooding. The seeds are inexpensive, and the grass is very hardy. Ryegrass can become weedy. Sow 1/2 to 2 pounds per 1,000 square feet.
Winter rye (Secale cereale): Grows 4 to 5 feet tall; hardy to -30° F. Best grass for cold winter climates: tolerant of low fertility, acidic soils. Sow 2 to 3 pounds per 1,000 square feet.
Oats (Avena sativa): Grows 2 to 3 feet tall: hardy to 10 to 20° F. Produces the least organic matter of grasses, but is tolerant of wet soils. Oats usually succumb to winterkill, but the residue is still beneficial to the soil. Sow 2 pounds per 1,000 square feet.
Barley (Hordeum vulgare): Grows 2 to 3 feet tall; hardy 0 to 10° F. Fast maturing and tolerant of dry and saline soils: intolerant of acidic soil. Sow 2 to 3 pounds per 1,000 square feet.
A common mix offered by seed companies is hairy vetch and annual rye. The vetch fixes atmospheric nitrogen, while the rye uses leftover nitrogen. Nitrogen from the decomposing vetch will cause the rye to decompose more quickly and not tie up nitrogen as long.
So get out there! The August air seems to get colder with each passing night, so that first frost can’t be too far away. Enjoy!