The Joy of Landscaping

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Cover Crops for Vegetable Gardens


Part 4: A Beginner's First Year of Vegetable Gardening


One of the first key points in this series was the importance of good soil for a vegetable garden. So last fall my raised beds were filled with "good soil", but would not be planted in until spring. What would the soil be like then? Hard as a rock and filled with weeds?

Cover crops are a good solution to dormant beds. Plant them in beds to keep weeds out and improve the structure and nutrients in the soil. Cut them down before planting the vegetables. The cut stalks can often serve as a mulch afterwards.

Since it was rather late in the fall when we finished completing our raised beds, it seemed that the best cover crop option was a combination of rye and hairy vetch. Winter rye is a grain that provides biomass and a framework to hold the feathery hairy vetch. Vetch is a legume, and fixes nitrogen. A 3 part rye to 1 part vetch proportion is commonly used.

So I broadcast the seed combination in the beds, lightly covered with soil, watered, and waited. The crops started coming up fairly quickly and got about 8" high, then seemed to go dormant over the coldest months of winter.

As I was starting to plan the timing of a spring crop of cool season vegetables, I realized I'd made a rather major mistake. If I cut down the rye too early, it would be coming back into the bed constantly. It should be cut down when it starts to shed pollen, after seedheads are formed. In our climate zone, this was not expected until mid to late May. Worse yet, rye is alleopathic, meaning it prevents vegetable plants from growing in its soil for awhile; I would need to wait at least 2 weeks once it's harvested to plant veggies.. So there was no way spring planting was going to occur.

While I was disappointed, it just meant that I would go big into planting cool season plants in the fall (and may have to delay planting warm season vegetables a few weeks). Certainly won't be the first mistake in this journey!

As to the rye and vetch cover crop, it got going again once the weather warmed. Every bed was densely filled with 2' high cover crops, so it certainly did the job. Since we had a cooler, very rainy May, the rye didn't get to the "pollen shedding" state until May 20, when I cut it down at the base, then laid it in the bed to create a mulch for the following 2 weeks. I should finally get my first warm season transplants in the ground in a few days.

So my verdict on a rye-vetch cover crop is that it does a great job of weed suppression and soil improvement, and is feasible for beds where you will only be planting warm season crops the following year. Just do NOT plant rye where you want to plant spring crops.

Regarding other cover crops, Buckwheat is a good filler crop in the summer in bare spaces as it likes heat but will die out in the cold (and can also be cut down anytime). I going to plant it in the "asparagus" bed, since I missed the timing for that this spring as well and want to keep weeds out and prevent the soil drying out over the hot summer. This fall, I'll try a cover crop combination of oats and Austrian peas in all the other beds. Supposedly these can be cut down anytime, so I can do a proper spring vegetable planting next year. Live and learn!