What to do during May in your garden and greenhouse.
Your monthly gardening checklists
Flowers
- 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, 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, such as fuchsias, 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, like carrots, 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
Greenhouse
- 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 if desired
- 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
- Start to harden off tender plants and bedding, ready for planting outside after the last frost
- Take cuttings from fuchsias, dahlias and pelargoniums
- Transplant tomatoes into growing bags or large pots, and tie their main stem to a cane or vertical wire for support
House plants
- Start feeding houseplants once a week with liquid fertiliser, continuing through to autumn
- Water your house plants more regularly as the temperatures warm, check the soil before watering. Take a look at our guide to watering house plants
- Repot any houseplants that have become top heavy or pot bound into larger containers
- Maximise the amount of light your house plants receive by moving to brighter spots, or choose house plants that will grow in shadier spots
- Some house plants, like snake plants, are particularly prone to collecting dust on their leaves. So be sure to give these a wipe regularly
- Try and keep house plants away from temperature fluctuations caused by draughts or central heating
- Check your house plants for pests like aphids, scale insects, thrips and mealybugs
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
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£49.98
2 x 35cm pre-planted baskets
These Pansy Cool Wave premium pre-planted rattan baskets provide an easy way to create a trail of colour and interest through the colder months. Chose from Berries and Cream or a Mix variety.
Offer Ends:
£0
£27.12
*Just pay £5.95 postage
From late spring, this Allium Bulb Bumper Pack will provide swathes of colour from a selection of classic varieties. Easy to grow in pots, borders, rockeries and grass, they also make great cut flowers.
Offer Ends:
£9.97
£14.97
3 x 9cm pots (1 of each variety)
Enjoy delicious blueberries fresh from your garden with this collection. Includes: 'New Hanover', 'Blueray' and 'Ozarkblue'. Bears sweet berries, rich in vitamins and antioxidants.
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