By clicking a retailer link you consent to third-party cookies that track your onward journey. This enables W? to receive an affiliate commission if you make a purchase, which supports our mission to be the UK's consumer champion.
Ceri studied horticulture at university and has spent her career editing gardening content. You shouldn't have favourites but she loves sweet peas!
May marks the transition into summer. Don't be in a rush to move patio pots and hanging baskets outside though. Check when the last frost date is in your area as you can safely move tender plants outdoors after this. The same goes for tender veg, such as courgettes and sweetcorn.
The grass will be growing strongly by now, so if you want a neat-looking lawn you’ll need to cut at least once a week. If you would like to encourage more flowers in the lawn instead, either raise the height of the blades or cut it less frequently so that plants, such as daisies and clover, can bloom and help pollinators.
Discover the best lawn mowers from our expert tests
May is the month to remove fleece covers from your veg, but have some at hand to cover newly planted or tender plants if frost is forecast. Hanging baskets, patio pots and tender border plants can also be moved outdoors once the danger for frost has passed. The later into May, the less likely it’ll occur, but a late frost could strike and blacken foliage and flowers.
Protect your plants from cold temperatures with the best frost protective covers
Any veg or flowers planted this spring will need regular watering while it settles in and puts down roots into the soil, especially during dry weather. This also applies to any new turf you may have laid.
Read our reviews of the best garden hoses and the best watering cans
A dry day is the perfect opportunity to kill weeds by hoeing them. Sharpen the blade of the hoe beforehand so that it will efficiently cut through thick stems. Hoe regularly, even if you can’t see any weeds, as it will disturb even tiny weed seedlings and stop them in their tracks.
Read our reviews of the best weed suppressing membranes
It’s best to wait until May before sowing French or runner beans, so they’re ready for planting at the end of the month. Plants sown too early will turn yellow if planted out early in May and will struggle.
Learn how to grow runner beans
Tomatoes for the greenhouse can be planted at the start of May; ones for outdoors can go out later in the month when the danger of frost has passed. Indoors, you can grow them direct in the greenhouse border or in pots of a Best Buy compost for containers or growing bags. Plant them deeply as they’ll make roots from the lower stem.
Find out how to grow tomatoes
Leeks that were sown last month can be planted outdoors. Allow around 30cm between rows to make weeding easier, and space plants at 15cm-intervals for full-sized leeks. If you’re short of space, plant closer together and harvest alternate plants as baby leeks, leaving the rest to grow on to maturity.
Learn how to grow leeks
Finish planting maincrop varieties, such as 'King Edward', by early May for crops in late summer/early autumn. Plant the tubers 40cm apart in rows that are 60-75cm apart.
Find out how to grow potatoes
This month, sow: courgette; dwarf and climbing beans; leaf beet; chard; beetroot; lettuce; basil; winter brassicas, such as Brussels sprouts; and spring onions. Sow leeks and winter squash, and cucumber for outdoors by early May; and swede at the end of the month.
Avoid potatoes turning green or being damaged by frost by covering the emerging leaves with soil or compost.
Whether sown in late summer or late winter, spinach naturally wants to flower (bolt) in May and June, so it’s best to pull up the plants and put them on the compost heap. Spinach can next be sown in August for crops from autumn to spring.
Make your garden better than ever! Our product tests and advice help you create the garden you want, all year for only £36.75 that’s 25% off.
Buy and saveSave 25% – was £49, now £36.75 for a year, offer ends 30 April 2026.
You can encourage your tulips to flower again next year by feeding them with tomato feed and removing any flowers that have faded. Bulbs in pots are best removed from the pots after they have finished, and then replanted deeply (around 15cm deep) in the border. Ones that are left in their pots tend to produce lots of small bulbs that produce leaves, rather than flowers, in their second year.
Discover the best tomato feed from the Which? Gardening magazine tests
Perennials put on a lot of growth in May, so keep an eye on your plants and tie them in to supports as they grow, or you can insert ready-made supports around them. Doing so will save any heartbreak later down the line when windy weather could snap the stems before they come into flower.
From mid-May, dahlias can be planted outside. Put in a sturdy stake so you can support them as they grow, and make sure to mulch around your plants. Watch out for slugs and snails, which love dahlias’ young growth.
Learn how to grow dahlias
If your borders are looking a little dull at the moment, try planting any of the following: Geranium pratense; Galega officinalis; Ceanothus ‘Concha’; astrantia; geum. Make sure to water them in well and keep watered during dry spells over the coming months.
Discover how to hardy geraniums and the best varieties
Peonies dislike dry weather in spring, so give them a good soak during spells without rain.