My "garden" consists of about 1/2 acre of sweetcorn. I dont plant any covercrop, but I use one that occurs naturally. I find that white clover comes in on its own every year after the corn, probably because the corn takes out so much nitrogen that grass can not compete. I rotate 1.5 acres or so total, so every 3rd year the corn gets planted in the same spot. The year after the corn, the white clover is a little spotty, but by the second year, when I plow it under for more corn, it is so thick you would swear it was seeded and treated with selective herbicide. I keep the 1 acre of clover mowed every couple of weeks and that helps the clover store up more nitrogen and controls other weeds. The clover, on the (2) off-years, really helps minimize the need for fertilizer on the sweetcorn. I go with a very light application of 15-15-15 for starter and that is it. The ears that we harvest are as big as any I have seen on roadside stands.