Sunday, April 4, 2010

Week of April 5 2010 : Covers

(Here is a picture of our cover crop. Last fall we seeded winter rye, hairy vetch and tillage radishes. The radishes winter killed last December, as expected, but first they established a long tap root. Now the rye and vetch continue to grow. The rye adds organic matter and the vetch fixes nitrogen from the air into the soil. The longer the cover grows, the greater the contribution to healthy soil but also the greater the difficulty working the soil.)

Normally floating row covers are critical to get transplants established in the field. The recent warm, no, HOT, weather seems to eliminate the need for row covers. But we should certainly be properly prepared for cool weather and frost.

Row covers serve two main purposes. They warm the transplants and exclude bugs. During the day, warmer temperatures encourage quicker growth. Warmer nighttime temperatures prevent frost. The covers also prevent pests from reaching the plants.

There are several row cover weights, but we prefer the lighter weight 0.6 ounce per square foot. The trick is to double and perhaps even triple cover the plants early in the season. As the season progresses and air temperatures rise, we remove one layer at a time. For particularly pest-sensitive crops such as cabbage we leave one layer as long as possible. Although this strategy demands more labor, it produces earlier and cleaner harvests.

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