Q What material should I use to fill raised beds?

A In the Which? Gardening magazine trial of the best soil mix for raised beds, we found that a mixture of 25% topsoil, 50% composted manure, and 25% sand and grit was best.

Although the mix was quite heavy to put in the bed, it didn’t settle much and was very easy to dig. It was easy to weed by hand, soil fertility was good, and we got the best yield of potatoes and carrots. The amount of moisture in the mix was well balanced, and it also had the warmest soil temperature – on average, 1.5°C warmer than the ground temperature in the early part of the year.
A mixture of 50% topsoil and 50% multipurpose compost was worth considering, but topsoil on its own was a disaster; it was cold, wet and heavy during the spring and lacked fertility, leading to a poor yield of potatoes and carrots.

Caption: Don't fill raised beds with topsoil on its own