What to do during May in your garden and greenhouse?

Garden Maintenance

· Transplant tomatoes into growing bags or large pots, and tie their main stem to a cane or vertical wire for support

· Garden maintenance

· Scoop out pondweed, blanketweed and algae from ponds and water features

· Put soft tops on the tips of all canes, in borders, veg plots, pots and greenhouses, to prevent injury to eyes

· Apply wood treatment to wooden garden furniture to condition it for summer

· Set up an extra compost bin or a worm bin, so you can recycle more green waste from your kitchen and garden

· Apply nitrogen-rich summer lawn feed to encourage leafy growth

· Mow grass pathways through wildflower areas so you can walk in among the flowers

· Hoe bare soil and hand-weed beds weekly, so weeds don't have time to establish and set seed

· Put supports in place for clumps of perennials that are prone to flopping, such as top-heavy peonies or phlox

· Trim topiary regularly to promote bushy growth and keep it looking neat

· Sow grass seed or lay new turf by the end of this month, to create a new lawn or repair damaged patches

· Check shrubs for nests before you start any pruning, to avoid disturbing nesting birds

· Clean out and scrub bird feeders regularly to maintain hygiene

· Build sturdy wigwams and supports for climbers such as runner beans, sweet peas and morning glory

· Watch out for aphids on shoot tips and young foliage, and wipe them off or spray with a soap-based solution


· Prune spring shrubs, such as forsythia and chaenomeles, after flowering to keep them compact

· Plant out dahlia tubers and cannas after all risk of frost has passed

· Tie in the new shoots of climbing plants, including clematis, wisteria and honeysuckle, to their supports

· Continue sowing annuals, such as California poppies, into gaps in borders for colour from August into autumn

· Plant up hanging baskets, but keep in a greenhouse or porch for a few weeks to establish, before putting outside

· Apply liquid feed to tulips, daffodils and other spring bulbs to encourage a good display next year

· Plant out summer bedding and tender annuals, including sunflowers, cosmos and nasturtiums, after the last frost

· Remove faded spring bedding, such as wallflowers and forget-me-nots, once faded and add to your compost bin

· Check lilies and fritillaries for scarlet lily beetles and their larvae, as they can rapidly strip plants of all foliage

· Harden off tender plants raised indoors, but bring them back in at night to protect from late frosts

· Pinch out the shoot tips of bedding plants and young annuals to encourage bushier growth

· Add interest to shady borders by planting a selection of hostas and ferns

Fruit and veg

· Earth up potatoes, covering the shoots with soil as they appear

· Sow sweetcorn in deep pots, so the young plants are ready to transplant into the garden in June

· Reduce snail populations by going on regular evening hunts, especially during damp weather

· Start sowing dwarf and climbing French beans, as well as runner beans, directly outdoors in warm weather

· Pick rhubarb stems as they develop, and water plants with liquid feed

· Start hardening off tender young plants, such as tomatoes and courgettes, ready for planting out in mild areas

· Sow batches of salad leaves and stir-fry crops every few weeks to provide continuous pickings

· Hang pheromone traps in apple and plum trees from May to July, to control pests

· Thin out seedlings from earlier sowings to ensure you get healthy, strong-growing plants

· Open fruit cage doors or lift some of the netting to ensure pollinating insects can get access to the flowers

· Remove all strawberry runners, so plants put their full energy into fruiting

· Keep plenty of fleece handy to protect young seedlings or fruit blossom, if late frosts are forecast


· Water thirsty crops such as tomatoes, cucumbers and courgettes regularly as the weather starts to warm up

· Tie the stems of indoor tomatoes, cucumbers and aubergines to canes as they grow

· Plant heat-treated freesia corms in pots for fragrant flowers this summer

· Check plants regularly for pests, on shoot tips and the underside of leaves, and treat with biological controls

· Put up shading to lower daytime temperatures and reduce scorching

· Open doors and vents on warm days, but close them in the evening as nights can still be cold

· Take cuttings of woody herbs such as hyssop, rosemary and thyme, and root in pots of gritty compost

· Keep pricking out seedlings as soon as they get their first true leaves, to avoid overcrowding and fungal diseases

· Repot any houseplants that have become top heavy, or pot bound into larger containers

· Start to harden off tender plants and bedding, ready for planting outside after the last frost

· Take cuttings from fuchsias, dahlias and pelargoniums

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