May is the busiest month in the UK garden. Keep mowing weekly, plant out tender vegetables and bedding after the last frost (third week of May in Surrey), deadhead tulips and daffodils but leave the foliage, sow runner beans and courgettes outside, and start a slug patrol. Leave one area unmown for pollinators. Everything else on this list is a bonus.
May is the month where the garden stops being a plan and starts being a place. The soil has warmed, the frosts are almost done, and everything you put off in April needs doing this week.
This guide is a categorised checklist — lawn, borders, planting, pruning, kitchen garden, wildlife, pests and water — with Surrey-specific notes where they matter.
Lawn Care in May
May is peak lawn growth. The grass doubles in pace and your mower needs to keep up.
Mowing
- Mow weekly from early May, and twice a week in warm, wet spells
- Drop the cutting height to 3–4cm for a finer finish, but no lower than 3cm
- Never cut more than a third of the blade in one go (the one-third rule)
- Alternate your mowing direction each week to stop the grass leaning
If you took part in No Mow May, you don’t have to leave the whole lawn — leaving one strip or back corner unmown is enough to help pollinators without losing the garden.
New lawns
Water newly laid turf or seeded areas deeply once or twice a week in dry spells. A good soak that reaches the roots is worth ten light sprinklings that only wet the surface.
Moss, feed and leftover jobs
- Apply a spring lawn feed early in the month if you haven’t already — a high-nitrogen feed greens the lawn and thickens it up
- Rake out moss now if you missed it in April. Scarify only lightly — heavy scarifying is an autumn job
- If you’ve got lingering bare patches, overseed them now while the soil is warm and moist
Borders and Beds
The border is waking up fast. Herbaceous perennials are bulking out, tulips are going over and the weeds are running.
Staking
Stake tall perennials now, before they flop. Delphiniums (Delphinium elatum), peonies (Paeonia), lupins (Lupinus) and tall asters all need support in place before a storm lays them flat. Once a perennial has fallen over, it rarely stands back up properly.
Hazel or birch pea sticks pushed in around the clump work well and disappear as the foliage grows through them.
Deadheading tulips and daffodils
Snap off the seed heads of tulips (Tulipa) and daffodils (Narcissus) as they go over — but leave the foliage alone for at least six weeks. The leaves feed the bulb for next year’s flowers. Don’t tie them in knots (an old-fashioned habit that reduces photosynthesis). Let them yellow and die back naturally.
Weeding and mulching
Weed the borders now while the weeds are small. Annual weeds come out with a hoe; perennial weeds (bindweed, ground elder, couch grass) need digging out by the root.
If you didn’t get a mulch down in March or April, it’s not too late. A 5cm layer of composted bark, leaf mould or home-made compost on moist soil will lock in moisture, feed the plants and suppress weeds for the rest of the year.
Tender perennials
In most of Surrey, the last frost is around the third week of May. Gardens on the North Downs (Box Hill, Ranmore, Leith Hill) can see frost a week later than the Mole Valley floor. Wait until the weekend of the 20th before planting dahlias (Dahlia), cannas (Canna), salvias and other tender perennials into the ground.
Planting in May
Hardening off
Any seedlings grown indoors or under glass need hardening off before they go outside. Put them out in a sheltered spot during the day for a week or so, bringing them back in at night. Gradually increase the time outside until they’re ready for a full night out.
Skip this step and the shock of direct sun and cold wind will stunt or kill them.
Tender bedding and vegetables
Once the last frost is safely past:
- Plant out tender vegetables (more on these below)
- Plant out summer bedding — cosmos (Cosmos bipinnatus), nicotiana, zinnias, tender salvias
- Move dahlias, cannas and pelargoniums outside
Biennials for next year
May is also the time to sow biennials that will flower next year:
- Foxgloves (Digitalis purpurea) — sow in trays or direct, prick out in summer
- Wallflowers (Erysimum cheiri) — for next spring’s bedding
- Sweet Williams (Dianthus barbatus)
- Sweet peas (Lathyrus odoratus) — plant out autumn-sown seedlings now with cane supports
It’s a small job that pays back with no effort at all next April.
Pruning in May
Most pruning is done by May, but there are a few jobs that land this month.
Deadhead spring flowers
Remove spent flower heads from rhododendrons, camellias and lilacs (Syringa vulgaris) as the flowers fade. This stops the plant wasting energy on seed and tidies the shape.
Pinch out sweet peas
Pinch out the growing tip of young sweet peas when they reach about 10cm. It triggers side shoots and gives you more flowers — more stems, more cut flowers, more scent.
Late spring-flowering shrubs
If you missed pruning spring-flowering shrubs in April, you’ve got a short window now. Forsythia (Forsythia × intermedia), flowering quince (Chaenomeles speciosa) and kerria (Kerria japonica) can all still be pruned this month, as soon as the flowers are over. Wait much longer and you’ll be cutting off next year’s flower buds.
Shape Clematis montana
Vigorous spring-flowering clematis like Clematis montana is pruned straight after flowering — usually late May into early June. Cut it back hard if it’s outgrown its space. It regenerates easily.
The Kitchen Garden in May
Plant out tender vegetables (after the last frost)
From the third week of May in Surrey, you can move these straight outside:
- Runner beans (Phaseolus coccineus)
- French beans (Phaseolus vulgaris) — dwarf or climbing
- Courgettes (Cucurbita pepo)
- Sweetcorn (Zea mays) — plant in blocks, not rows, for pollination
- Squash and pumpkins
If you started them indoors, harden them off first. If you’re sowing direct, the soil is warm enough now.
Direct sow
Sow these straight into warm soil outside:
- Carrots (Daucus carota) — successional sowing every two weeks
- Lettuce (Lactuca sativa) — pick a shaded spot in hot spells to stop bolting
- Beetroot (Beta vulgaris)
- Radish (Raphanus sativus) — ready in four weeks
- Peas (Pisum sativum) — last sowing of the year for most of the South
Greenhouse tomatoes
Plant out tomatoes (Solanum lycopersicum) in the greenhouse border or grow bags now. Tie them in, remove side shoots on cordon varieties, and start a weekly tomato feed once the first truss has set.
Wildlife in May
May is one of the most important months for garden wildlife. Every decision you make helps or harms.
- Leave one area of lawn unmown for pollinators — even a small patch of 2×2m produces ten times more nectar
- Top up bird baths and water bowls — May is thirsty work for nesting parents
- Do not trim hedges. Bird nesting season runs March to August, and every UK gardener is legally responsible for checking hedges aren’t active before cutting. Hedge work waits until late summer
- Leave a patch of nettles for butterflies (peacocks, red admirals, commas all lay eggs on nettles)
Pest Watch in May
May is the month soft young growth meets hungry pests.
Slugs and snails
Slug patrol starts now. A warm wet night can strip a hosta or a row of lettuce in hours. Practical defences:
- Check plants at dusk, especially after rain, and remove what you find
- Use nematodes (a watered-on biological control — effective and safe for wildlife)
- Copper tape round pots, wool pellets round vulnerable plants
- Skip the blue slug pellets — they harm hedgehogs, thrushes and ground beetles
Lily beetle
Bright red lily beetles (Lilioceris lilii) on lilies and fritillaries need picking off by hand — they’ll strip the plant in days. Check the undersides of leaves too.
Vine weevil
Pot plants wilting for no reason? Tip them out and check the rootball for vine weevil grubs — creamy white with a brown head. Nematode drench in May and again in September keeps them under control.
Water in May
Water butts
If you haven’t done it already, get water butts connected now. Every downpipe can feed a butt, and in a Surrey summer a single water butt saves hundreds of litres of tap water and gives plants better, softer water.
Watering new planting
Water anything planted in the last 12 months deeply, once a week. A long soak that reaches the roots is worth ten light sprinklings. Established borders rarely need watering in May in the UK — they should be finding their own water.
Pot plants and hanging baskets need checking daily once the weather warms up.
Your May Checklist at a Glance
| Category | Priority job this month |
|---|---|
| Lawn | Mow weekly, feed, consider No Mow May |
| Borders | Stake tall perennials, deadhead bulbs, mulch |
| Planting | Harden off, plant tender perennials after 20 May |
| Pruning | Deadhead spring flowers, pinch sweet peas |
| Kitchen garden | Plant out beans, courgettes, squash; direct sow salads |
| Wildlife | Leave one unmown area, do not trim hedges |
| Pests | Slug patrol, check for lily beetle and vine weevil |
| Water | Set up water butts, deep soak new planting weekly |
Frequently Asked Questions
Can I plant out tender plants in May in the UK?
In most of Surrey and the South, wait until the third week of May for tender plants like dahlias, cannas, runner beans and courgettes. Higher parts of the North Downs can get a late frost into the last days of May, so err on the side of caution. Harden seedlings off for 7–10 days before planting out.
What vegetables can I plant in May?
Outside after the last frost: runner beans, French beans, courgettes, sweetcorn, squash and pumpkins. Direct sow: carrots, lettuce, beetroot, radish, peas and spring onions. In the greenhouse: plant out tomatoes, cucumbers, peppers and aubergines.
Should I stop mowing for No Mow May?
You don’t have to stop mowing the whole lawn. Leaving one section or a back corner unmown for May (and ideally into June) is a practical compromise — it gives pollinators a real boost without losing the garden. Cut the long section once at the end of June, then resume normal mowing.
Is May too late to plant bedding?
No — May is the right time for tender summer bedding in most of the UK. Hardy bedding can go in earlier, but tender plants like cosmos, nicotiana, zinnias and tender salvias should wait until after the last frost (third week of May in Surrey). Plants set out too early often sulk for weeks and rarely catch up.
What should I be doing in the garden in May?
The priority jobs are weekly mowing, planting out tender vegetables and bedding after the last frost, deadheading spring bulbs while leaving the foliage, staking tall perennials, starting slug patrol and leaving hedges alone for nesting birds. If you do nothing else, do those six things.
When is the last frost in Surrey?
The average last frost date for most of Surrey is around the third week of May. Gardens on the North Downs ridge (Ranmore, Leith Hill, Box Hill) often see frost later than the Mole Valley and Wey Valley floors. Check your own garden — frost pockets are local.
Need a Hand With the May Rush?
May is the month that catches most gardeners out — there’s too much to do and it all needs doing at once. We handle weekly mowing, bed maintenance, staking, planting out and the rest of it as part of year-round garden maintenance across Surrey and Sussex from our base in Dorking. If you’d rather be enjoying the garden than chasing it, get in touch for a site visit.
