Seasonal Guide to Sowing Vegetables in Raised Beds

Why Raised Beds Get You Sowing Weeks Earlier

A raised bed is, in effect, a small climate of its own. Because the soil sits above the surrounding ground and is exposed to sun and wind on all four sides, it drains faster and warms faster. In a mild British March, a well-built bed filled with a decent loam can be three or four degrees warmer than the ground beside it — often the difference between sowing and waiting.

Before you sow anything, spend an afternoon on preparation. Top up each bed in late winter with a 5cm layer of well-rotted manure or garden compost, fork it in lightly, and let the bed settle for a fortnight before sowing. Work from a plank laid across the timbers rather than treading on the soil; compaction is the quiet enemy of root crops. If a cold snap is forecast, a cloche or a double layer of horticultural fleece will buy you another week or two for very little cost.

A Simple Rotation Worth Keeping

Raised beds make rotation easier because the plots are already divided. If you have four beds, group your crops like this and move each group on one bed every year:

• Legumes — broad beans, peas, runner beans, French beans. These fix nitrogen and leave the soil richer than they found it.
• Brassicas — cabbages, kale, purple sprouting broccoli, sprouts. Follow the legumes to make use of that nitrogen, and net them against pigeons and cabbage white butterflies.
• Roots — carrots, parsnips, beetroot, swede. Fresh manure makes these fork and split, so grow them in the bed that was manured two seasons ago.
• Potatoes and everything else — new potatoes, courgettes, salads, onions, chard.

The golden rule is never to follow carrots with carrots; carrot root fly overwinters in the soil and will find the seedlings again. Three beds work almost as well — simply rotate legumes, brassicas and roots, and tuck salads into the gaps wherever there is room.

What to Sow and When

March is the month the beds come alive. Under fleece you can sow carrots, radishes, lettuce, spinach and early beetroot. Broad beans sown in autumn are already flowering, and a second sowing now will crop into summer.

By mid-April the soil is usually workable without any protection. Sow beetroot, chard, spring onions, peas and more salad, and start off courgettes and sweetcorn indoors for planting out after the last frost. In the south, that is usually mid-May; in the north, give it another fortnight.

May is for the tender things: runner beans, French beans, outdoor cucumbers and squash. Keep sowing a short row of salad every two to three weeks rather than one long row, and you will eat leaves from May until October instead of drowning in a single glut.

Getting Carrots, Lettuce and Radishes Right

Carrots want a fine, stone-free tilth and consistent moisture. Sow thinly in drills 1cm deep and 15cm apart, mixing the seed with a little dry sand to spread it further. Water the drill before sowing, cover lightly, and water again gently. Once the seedlings are 2cm tall, thin them to about 5cm apart in the evening, when the scent draws fewer flies, and remove the thinnings from the plot. A barrier of fine insect mesh over the row is the most reliable defence against carrot root fly.

Lettuce is best treated as a cut-and-come-again crop. Scatter seed thinly in a shallow drill, keep it damp, and start cutting leaves when they are 8cm tall. For hearting varieties, thin to 20cm. In high summer, sow in the shade of taller crops or give the bed a little afternoon shade, or the plants will bolt.

Radishes are the quickest reward in the garden — ready in three to four weeks from a 1cm-deep sowing. Sow little and often, thin to 3cm, and water regularly; dry soil makes them woody and hot. They are excellent sown between slower rows of carrots or parsnips to mark the line.

Foraging the Hedgerows While the Garden Grows

Country living and vegetable growing go hand in hand with a wander along the lane. April brings wild garlic in damp woodland — pick a few leaves from each clump so the bulbs stay put — and young nettle tops for soup. From late May the elderflowers are out, and a bottle of elderflower cordial is one of the great rewards of a hedgerow walk.

Later in the year come blackberries, then sloes after the first frost, rosehips, haws and crab apples for jellies. Pick only from abundance, leave plenty for the birds and dormice, and never dig up a wild plant. Avoid verges that may have been sprayed, keep to public footpaths, and ask permission before picking on private land. Above all, only pick what you can identify with absolute certainty.

Keeping the Soil in Good Heart

Healthy raised beds are fed from the top. Mulch around established plants with compost in early summer, water deeply rather than little and often, and leave the soil undisturbed wherever you can — the worms and fungi will do the digging for you. Watch for slugs in wet spells, and set a few beer traps or night patrols with a torch.

When a bed empties in late summer, sow a green manure such as field beans, grazing rye or phacelia instead of leaving bare soil to be leached by autumn rain. Cut it down before it seeds and leave the tops to wilt on the surface as a mulch. Do that, rotate your crops sensibly, and your raised beds will go on giving you early carrots, endless salad and a genuine taste of the British seasons for years to come.