Friday, October 7, 2011

Season Endings and Beginnings

Vegetable Endings
With night temperatures predicted to drop into the thirties F this coming weekend, it's time to harvest what remains of tomatoes, peppers, eggplants and many other fruiting vegetables. Thirty degree temperatures are flavor killers for tomatoes anyway so using ripe fruit and ripening mature green or pink breaker fruit indoors is preferable.

Cover Crop Beginnings
Clearing plant refuse off the growing area now has another advantage. Mid-October is a good time to plant winter cover crops for soil improvement. Maintaining desirable levels of both organic matter and nitrogen in your soil is important for growing vegetables. Nonlegume cover crops help with organic matter and legumes can add both.

One common cover crop planted in our area is winter rye but there is a lot of confusion about what that is. Winter rye is cereal rye, Secale cereale, the same rye used for grain. Annual or Italian ryegrass, Lolium multiflorum, can be used as a cover crop in certain circumstances but winterkills in cold, dry Front Range conditions. Annual rye should be sown in early fall, so it's now late to plant.

Winter rye on the other hand is one of the hardiest of cereals and can be seeded later in fall. Growth is rapid in cool fall weather and its quick-growing, fibrous roots hold soil and leftover fertilizer well. It is also good at suppressing weeds.

Rye can also be sown with legumes in fall. Hairy vetch, Vicia villosa, is one of the most popular. It's winter hardy to zone 4 and can work in zone 3 with snow cover. It grows slowly but root growth continues over winter and vine growth quickens with arrival of spring. It tolerates poor soils (including sandy ones) and delivers a heavy contribution of nitrogen compliments of it's symbiotic nitrogen fixing bacteria.

A type of field pea (Pisum sativum subsp. arvense), Austrian winter pea, can also be used as a winter legume. It is not as cold hardy as hairy vetch and should be seeded in early fall. Plant it with a winter grain such as rye to protect pea roots and maximize winter survival. It prospers best with some winter moisture.

A rule of thumb is to plan for at least a month in spring after turning under cover crops to allow them to decompose before planting vegetables.

Photo credit: Tomato harvest and Rye/Hairy vetch seed - both Carl Wilson


  1. Can you share suggestions on where to buy cover crop seed? Thanks!

  2. This is terrific info. I am not finding any hairy vetch retailers in Denver, do you know of any local sources?
    Thanks for this wonderful blog!!

  3. Where do you find seed for the cover crops you suggest?

  4. Down here in Texas, clover is a great winter ground cover between plantings. It's a good nitrogen builder and keeps weeds at bay.

  5. Try a farm seed supplier like Arkansas Valley Seed (Longmont), Sharp Brothers Seed (Greeley) or an online catalog such as Johnny's Seeds.

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