This time of year in our zone it is almost impossible to get a cover crop to develop without extensive watering and then it just shallow-roots. It is just too hot. Later this fall, no problems, and any of the clovers is an excellent choice.

You could accomplish the same thing with a good thick layer of organic mulch - compost or composted manure (more N), even chipped hay. As it decomposes it will provide nutrients to the soil. Other option for nitrogen is alfalfa meal/pellets. Put it on now and then plan to plant CC this fall.

But keep in mind that N is seldom tested for professionally simply because it is so volatile and quickly dissipates. So they usually just make the flat recommendation to add N even though there may be plenty there - it just won't show up in the testing. So don't go overboard with N additions or you may create even more problems in the long run. ;)

Dave

Most any legume that would still germinate would not have time to set the Nitrogen before needing to be cut down for that fall planting, however Buckwheat will germinate and grow and add a lot of organic matter to your soil and will still germinate and grow (it is a warm weather crop). I would be less concerned about getting the Nitrogen in the soil raised then I would in gettng more organic matter in there since a good active Soil Food Web will take care of the N needs of the plants.

Thanks, Dave and Kimmsr. I will forget about legumes then, and plant buckwheat. Depending on my wallet, I may or may not be able to buy all the other dream items for the bed this fall, so I can still use the red clover later. Or would it be better just to let the buckwheat die down of its own accord and rot in place this fall? I've never used a cover crop, unless you count weeds!

Virginia in Virginia

Oh, well, when I was at the Farmers' Coop, I couldn't resist buying a small bag of cow peas, along with the 15 lbs of buckwheat the cashier recommended. Since he looked cross-eyed when I asked him how much seed I needed for 600 sq ft, I'm not too sure he came up with the right figure. I opted for the lower of the two - he suggested 15-20 lbs - but it still looks like too much, especially if I also put in a row or two of cow peas. Any advice on quantity? Do I just broadcast it, or do I need to cover it? How deep should the cow peas go? I bought innoculant too.

Virginia in Virginia

You might have a problem trying to grow both at the same time; buckwheat jumps up quickly if you have sufficient rainfall or good soil conditions and will shade the legume.
You'll need to cover it after broadcasting, but not by much. It can root on the surface but not as well and birds like to eat it.
It can be sown heavily; a guess, maybe twenty seeds per sq.in. Such a rate will choke other things if the buckwheat gets a head start. It's easy to turn back in compared to other covers.

I was going to recommend buckwheat and black-eyed peas yesterday, but I couldn't remember where I had seen this question. Peaceful Valley Farm Supply says 3 lbs of buckwheat for 1000 sq-ft or 2-3 lbs of their 70/30 buckwheat and cowpea mix. I always buy my small quantities of cover crop seed from the bulk bins at Whole Foods....

LOL! I just broadcast all 15 lbs on my 600 sq ft bed. I guess I'm going to have very crowded plants. It did seem like an awful lot to me. Then the black-eyed peas: one place said to plant them 2" deep, another 1/2" deep. Who knows what will come up!

Here's the bed. That's the neighbor's goat shed on the left, not our house: {{gwi:298586}}
Here's the bed with my painting studio on the right. {{gwi:298587}}