Gardening tips for April

Crop Rotation

By now, you should have your crop-rotation plan ready for the year. This is most important in an organic kitchen garden, as it’s easier to control soil-borne pests and diseases when the crops are rotated onto different plots each year. Also, unrotated crops planted year after year in the same spot deplete the soil of the nutrients that they require. A rotation will ensure that this doesn’t happen. A three-year rotation (or four, if you leave a plot to lie fallow each year) will see hungry crops, such as peas, beans, sweetcorn, onions, shallots and so on, growing on well-manured ground; another bed will have all the Brassicas (kales, cabbages, cauliflowers, brussels sprouts) on ground that needs lime in the soil; the third plot can be given over to root crops, such as potatoes, carrots, parsnips, and so on. By circulating them in this order, good fertility will be maintained in each plot from year to year.


The soil should now be warm enough to sow carrots. Our system is to sow them in three rows, with each row 12in apart. The bed is then covered with a light fleece to keep out the carrot root fly, which lays eggs at the base of the seedlings at their most vulnerable in May and September. The grubs burrow down into the carrots, making them inedible. An alternative protection is a 30in-high ‘fence’ of fleece or plastic fixed around the bed, the theory is that the carrot root fly flies low to the ground and doesn’t find the crop, but we’ve found that covering with fleece is the easiest and most effective prevention. Make sure that the fleece is twice the width of the bed to allow for the growth of the carrot foliage. Fasten down the sides with pegs, stones or bricks. The fleece should stay on all year and is only removed to weed the carrots, if necessary, when they are 2in to 3in high.


It’s worth sowing some beetroot early, with some protection if needed. You can sow successively through the spring for use in summer, increasing the amounts as the season advances, for winter storage. Sow thinly as each little cluster contains several seeds.


Now is a good time to remove any moss in your lawns. Consider hiring a Verticut machine. It has steel blades an inch apart on the fast, rotating cylinder and is more effective than the tines of domestic scarifiers. Set it to touch the lawn surface to ‘de-thatch’, and allow air and rain to penetrate the soil. Don’t throw away the thatch it lifts out, as it can be used as a mulch around trees. The grass shouldn’t need any fertiliser, unless you’re on poor, free-draining soil. The choice of mower is up to you. We usually use mulching mowers. They’re speedy, there are no trips to the compost heap, and the cuttings help to feed the soil.


It will pay dividends to hoe your flower borders now. You’ll get the first spring weeds when they’re small.

Philip Maddison is head gardener at Harrington Hall, Lincolnshire (


‘Ne’er cast a clout til May be out’, say the old gardeners, warning against planting out annuals until the frosts are over—hopefully by the end of May. Now is the time to sow Nicotiana affinis and bed dahlias, as they grow rapidly from seed, and are ready to plant out after six to eight weeks.

Often underrated, dahlias are easily grown from seed. Plant them thinly on a seed tray and cover them with compost. They’ll germinate rapidly if left on a heated bench. Prick out the seedlings early into 24-cell plug trays. Nicotiana seedlings need more delicate handling, but grow rapidly once pricked out. Plant them out before they get root-bound in the plugs.

Celery and Celeriac

Choose a self-blanching celery, so you’ll have no need to trench and ‘hill-up’ later.

Sow the seeds thinly on a seed tray and don’t cover; a sheet of plastic will keep the surface moist. Prick out into plug trays when one or two leaves appear. For best results, avoid the stress of cold or drying out when they’re growing on. Plant out with 9in spacings when the weather’s warmer out; don’t disturb the roots.

Celeriac is grown in the same way, but as the root will be eaten, you don’t need to plant them closely. In mild areas, the rather ugly root can be left in the ground for use through the winter; otherwise, put it in a box with a damp medium, such as coir fibre (from The Organic Gardening Catalogue, 0845 130 1304,

Both vegetables need moisture-retentive and humus-rich soil to succeed, so mulch with grass clippings in the summer to conserve moisture.


Try sowing in pots—preferably Jiffy pots—to reduce root disturbance. Sow three to five seeds to a pot, keep in a cold greenhouse and plant out, nine inches apart, as soon as possible after germination. This way, you avoid sowing in cold and wet ground, which peas hate.

If you use an early variety, you can sow at intervals for continuity. For a change, try the tall mange tout Ezethas Krombek Blauwschok with its edible purple pods (from The Organic Gardening Catalogue); the violet flowers can rival sweet peas.


To get the most from a packet of seed, sow in plug trays all through the growing season. Put three seeds in each plug and thin to one when they germinate. Plant them out when they’re large enough to handle. Be careful not to disturb the roots when you push them out of the plug. Protect with fleece if there’s still a risk of frost when planted.