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After all risk of frost has passed this month, plant out tomatoes, courgettes and pumpkins that were previously sown under cover. Other young plants can be planted out once conditions are suitable, and once they've been hardened off.
Plant out alpine strawberry seedlings sown in early spring.
Sow outdoor melons in a heated propagator.
Sow French beans, runner beans, squash, cucumbers and pumpkin seeds directly into prepared beds outside. Be alert to late frosts (for which a covering of horticultural fleece should provide sufficient protection).
Sow sweet corn outside in blocks, at least 45cm (18in) spacing, with two seeds per hole. The strongest seedling can be selected later.
Sow cauliflowers and purple sprouting broccoli for harvesting next winter.
Try sowing some unusual vegetables such as kohl rabi (like a large white above-ground turnip), scorzonera and salsify.
Witloof chicory can be sown this month, to have some ready for forcing next winter. Sow in drills directly outside.
After all risk of frost has passed, plant out tomatoes, courgettes and pumpkins that were previously sown under cover.
Other young plants can be planted out once conditions are suitable, and once they've been hardened off (acclimatised to the colder outdoor conditions) for 10 to 14 days.
Brussels sprouts for next winter should now be ready for transplanting after early or mid-spring sowing.
Plant out artichokes that were previously sown under cover.
Self-blanching celery can also be planted out towards the end of the month.
Ridge cucumbers can be sown indoors now, for planting out in early June.
Remove wayward shoots on fan-trained trees and tie in better placed ones.
Thin out crowded raspberry shoots.
Thin gooseberries if you want large fruit.
Tie in leading and sideshoots of kiwifruit.
Keep an eye out for asparagus beetles, and pick them off by hand.
Watch for the small holes flea beetles make on brassica seedlings. Water plants well to help them continue growing despite the pest damage.
Protect carrots with insect-proof mesh to prevent carrot root fly.
Slugs pose a threat, and slug controls are necessary now, as always.
Protect brassicas and peas from pigeons.
Pick yellowing leaves off brassicas promptly, to prevent spread of grey mould and brassica downy mildew.
Deal with apple sawfly and capsid bug and prevent blossom wilt if it struck last year.
Put up codling moth traps in apple trees.
Look out for spur blight, cane spot and cane blight on raspberries, blackberries and hybrid berries.
Put bird protection in place for all soft fruit.
Deal with raspberry leaf and bud mite and raspberry rust from now on.
Keep on top of weed control and continue through to summer.
Pull off suckers appearing around the base of fruit trees.
Liquid feed fruit trees growing in pots with a balanced feed every fortnight.
Deblossom strawberry runners planted since September.
Water blueberries, cranberries and lingonberries when needed with rainwater, but use tap water when butts are empty.
Take softwood cuttings of kiwifruit.
Remove any winter protection from figs and carry out pruning.
Move growing-bags into the greenhouse to warm up two weeks before planting indoor melons, and water well two days before planting.
Gently run your hand over indoor grape vine flowers to pollinate them.
Make sure fruit isn’t drought stressed, especially those in containers, against a wall or newly planted.
Make sure bees can access caged and cloched fruit flowers to ensure pollination.
Keep a check on late frost forecasts and protect blossom as necessary.
Earth up potatoes when the shoots are 23cm (9in) high, in order to prevent the new tubers going green. Earthing-up is the drawing up of soil around the stems of the plants, leaving just 5cm (2in) of shoot uncovered so that the plant has enough foliage to continue growing.
Start to remove sideshoots from cordon tomatoes as you see them. The sideshoots develop in the leaf axils (i.e. between the stem and leaf), and if allowed to develop will sap the energy of the plant and reduce the quality of the yield.
Strings stretched along the tops of broad bean plants can support them, and prevent them flopping once pods develop.
Peas need staking with pea sticks, netting, or pruned twigs from the garden.
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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.