use newspapers, if possible, try to do this when it is/has been raining. Spread about three layers of newspapers in the valley between rows and up to the top and a bit over. You will have to tear the edge of the paper to go around the haulms and try to sort of interweave the layers. If not raining, get paper nice and wet and it turns to a papier mache. It suppresses the weeds and keeps light off, is supercheap, if a bit tricky but it really does work.
cheers, suzy