The Wrong Cover Crops

When I created my recent hugelculture bed, I had no turf to invert on top and give it a stable layer of soil. So incorporated a couple of cover crops into the mud that I plastered it with: clover and buckwheat. Clover of course fixes nitrogen and buckwheat is known for growing rapidly. They both provide bee forage. They're commonly used and easy to obtain. But they were the wrong choices for my conditions.

My most problematic weed species is oxalis pes-caprae, a practically ineradicable South African bulb known locally as sour grass. Its bulbs remain deep underground, and the leaves and flowers spring up rapidly in the winter, about early February. Being a bulb it has more stored nourishment than the little seeds I plant that take a while to grow their first true leaves. It becomes so abundant that it keeps all the sun off my seedlings, which disappear in the thick leaves of the sourgrass.

It's debatable whether it provides forage for honeybees, I have heard that it doesn't, from someone who ought to know, and read that it does. Beyond its habit of taking off so rapidly in the first warmth of the year, it is a fairly innocuous plant. No stickers, no poison, I like the color. The stems are succulent and the leaves are roundish in clumps of three. It is lovely, bright and cheerful, and smells good. It disappears by summer. But I am tired of it crowding out the what I plant. So I keep pulling it up, hoping eventually to starve the bulbs, at least in my vegetable beds.

Did the description of the leaves sound familiar? How about the stems? What has roundish leaves in clumps of three? Clover. And succulent stems? Buckwheat. It's nearly impossible to weed sour grass when it's surrounded by two plants that look just like it. If I concentrate on the leaves I end up pulling all my clover. If I look at the stems I yank the buckwheat. If I try to leave the cover crops for soil stabilization and to feed the bees, I end up with plenty of sour grass setting new little bulbs to sprout from next spring, when I'd really rather be growing peas and radishes, chicory and beets.

Next time perhaps I'll try vetch.