By far the easiest way to build soil structure and add nutrients is through growing green manure cover crops when the garden beds are bare. High in nitrogen green manure crops are ideal for growing before a hungry crop is to be planted in the same area later in the year.
There are two types of green manure seeds to grow, Spring and Autumn sown.
Spring sown varieties add a significant amount of bulk to build the soil structure. The downside being that they occupy the garden when most crops should be in the ground.
Autumn sown green manures are much more popular. Once the main garden crops have been harvested the green manure seeds are sown and allowed to grow until early Spring when the plants are dug in the soil.
Both of these types are wonderful for the soil. Adding structure, nutrients and preventing any weed growth. Green manures grow fast and will prevent almost all weeds from becoming established. Soil structure is significantly improved, the roots open the soil structure and digging the plants into the soil add humus that builds the soil.
There are two types of green manures that I would recommend.
Spring Sown Crimson Clover – ideal for sowing in May for digging into the ground in July. Clover is very high in nitrogen and ideal for growing before planting a hungry crop the next season. The plants are very good at preventing any kind of weed growth.
Autumn Sown Grazing Rye – produces deep roots adding air and fixing the soil structure. Rye can be sown once main season crops have been harvested. Sow September for Spring digging. One of the few green manures that can easily survive the winter frosts.
Once grown the green manures should be cut at the ground and left for a day to wilt. It’s then time to dig this organic matter into the soil.
Adding and digging in such mass of green organic matter in the soil will seem strange but this will very quickly compost into the soil. Ideally you should allow two weeks after digging the green manure into the soil before planting anything else in the bed. The tender green manure leaves will quickly rot down into the soil.