An idea I got from a number of sources so it isn’t mine but it really works a treat. Even if you don’t have a greenhouse it works just as well. Take a length of guttering that suits your purposes and fill with cheap multi-purpose compost. Plant in your favourite salad seeds, beetroot or vegetable or herb (parsley for instance). Keep well watered in the greenhouse or covered with fleece or pastic sheet outside. When the seeds have grown big and strong you can slide out the contents into their final place in the garden. I’ve normally got about 5 gutters on the go at any one time and when one is emptied into the garden I fill it up for the next set of planting. The method helps you keep a better rotation of salads and seedlings than simply planting straight into the garden.