I want to plant a green manure...

You can plant numerous green manures in June. You simply need to decide which soil quality you’re shooting for and how quickly you want to replant your garden plot. If you’re devoting this summer to renewing the soil and won’t replant until next spring, you have lots of choices. Some green manures, such as alfalfa, are particularly suitable for breaking up heavy soils. Its deep roots will open up and aerate the soil once the crop is rototilled back into the earth. If you’re after nitrogen, choose one of the legume varieties, such as vetch, fenugreek, red clover, or black medick. Keep in mind that red clover is a perennial, which means that it might continue to come up in future years. If that’s a problem, choose one of the others. After two to three months in the ground, these crops can be rototilled into the soil or cut and left on top of the soil as mulch. Either way, they will release their nutrients slowly into the soil, improving it for future use. Wait at least three to four weeks, or until the following spring, before planting anything else in the area.