Midlothian, Scotland

How long does green manure need to rot down once it has been dug in?

I have just ordered a mix of winter green manure to cover my veggy patches as they are bare at present so the rain will be leaching goodness away. Plus I hope a web of greenery on the surface will stop that cheeky b&w cat next door using them as a toilet! If I dig over, compost and sow green manure this week when should I prepare the seed bed - will April/May be too late?

• 6 Sep, 2010