How long after digging in green manure (clover), should I wait to plant seeds? And why? I wanted to plant a lettuce mixture soon but just started digging in green manure today. My understanding is March is the best time to plant lettuce, but I feel like I might have to wait until April now if my green manure needs to rest.
During my research to answer your question, I found suggestions of wait time between soil incorporation and planting time to range anywhere between one and four weeks. An article from Oregon State University Extension suggests waiting a minimum of 3 weeks before planting; see Buckwheat a Good Summer Cover Crop for Home Gardens.
But alternative methods are available to manage cover crops. One is to cut the crop, allow the cut portion to lie in place and act as a mulch for the soil, then gently clear small areas where you’ll set your transplants. Another option is to compost the cut portion, then plant into the stubble.
You might like to review the publication "Growing Your Own" which is an overview of vegetable gardening. Page 7 is a helping chart with planting dates for seed and transplants. In that chart, you’re in Region 2.