For early vegetable crops you can use your coldframe if you are not using it for over-wintering plants. Turnips and radishes are among the crops that grow quickly and mature early in a coldframe, but you can also try forcing varieties of carrots that are suitable for early sowing. Some varieties of lettuce also do well in a coldframe as an early crop.
Prepare the soil by digging over the ground in the frame and work in as much organic material as possible. Well-rotted farmyard manure that has been put through a sieve is useful for enriching the soil for these early crops. Do not apply powerful artificial fertilizers at this time. Rake the soil level and make shallow drills with your rake or hoe. You can sow the seeds scattered randomly, but this makes weeding and thinning more difficult, especially if you new to gardening and don’t know much about how the seedlings look.
Sow the seeds thinly then rake the soil back over the drills. Water thoroughly then keep the frame closed until the seeds germinate. Once they are through, ventilate on mild days, but keep closed and if possible insulated at night, especially when frost is forecast.
Peas and beans germinate readily in warm soil in early spring but you can get them off to a flying start in late winter by sowing them in pots or in a length of gutter indoors. This technique is also useful for keeping sowings on schedule if your garden soil is a heavy one – this type of soil is slow to warm up in spring, or if the weather is particularly cold or wet.
You can grow beans and self-blanching celery in a soil that has not been specially enriched with organic matter, but fro good crops you should prepare the planting trench thoroughly first. Take out a trench of 25-30 cm deep and 60 cm wide for runner beans and 38 cm wide for celery. Heap the soil to one side or both sides of the trench and add as much well-rotted manure or garden compost as you can spare. This will add some nutrients and improve the soil structure and its moisture-holding capacity. Fork the compost or manure into the soil at the bottom of the trench; don’t leave it as a layer. Rake the excavated soil into the trench and you are ready.