What to Plant in May

Vegetables to Sow and Plant in May

May is the pivotal month in the UK gardening year. The last frost typically passes between mid-April (southern England) and mid-May (Scotland), and once it does, the floodgates open. Everything you have been nurturing on windowsills and in greenhouses since March can finally go outdoors. At the same time, the warm soil and long days make outdoor sowing incredibly productive.

Direct Sowing Outdoors

The soil is now warm enough (12-15°C in most of the UK) for rapid germination. Seeds sown in May often outperform earlier sowings simply because conditions are so much better.

French beans and runner beans can be sown directly outdoors from mid-May in southern England, or late May further north. Sow French beans 5cm deep, 15cm apart in rows 45cm apart. Runner beans go 5cm deep, 15cm apart, at the base of a support structure — a wigwam of bamboo canes works well. A single wigwam of 8 canes will give you a huge crop from July to October.

Beetroot, carrots, lettuce, radishes, rocket, spinach, spring onions and turnips all continue from earlier months. Keep up successional sowing — a new row every 2-3 weeks gives you a continuous supply all summer. May-sown carrots are your main-crop, destined for autumn and winter storage.

Sweetcorn can be sown directly outdoors in late May. Sow two seeds per station, 2.5cm deep, in a block pattern (not rows) with 45cm between plants. Blocks give better wind pollination than single rows, which means fuller cobs. Thin to the strongest seedling after germination.

Peas — final sowings of early varieties for a summer crop. Later sowings after May tend to suffer from pea moth and mildew.

Kale sown now will give you a crop from autumn right through winter and into next spring. It is one of the hardiest vegetables and will keep producing after everything else has stopped.

Planting Out: The Big Move

This is the moment you have been waiting for. All those seedlings raised indoors since March can finally go outside — but only after the last frost has passed. In southern England this is typically mid-May, in the Midlands late May, and in northern England and Scotland late May to early June.

Tomatoes are the most important plant-out of the month. Harden off for 7-10 days before planting permanently. Plant deeply — bury the stem up to the lowest set of leaves, as tomatoes will root from the buried stem and produce stronger plants. Space 45-60cm apart. Stake or cage immediately at planting time. If growing outdoors (not in a greenhouse), choose blight-resistant varieties like Crimson Crush, Mountain Magic or Ferline.

Courgettes and squash are hungry, thirsty plants. Plant into soil enriched with well-rotted compost or manure, and space courgettes 90cm apart. Two plants is enough — seriously, just two. Each plant will produce 15-20 courgettes over the summer. Winter squash like butternut needs 1.2m spacing.

Pumpkins need even more room — 1.5-2m between plants. Enrich the planting site by digging in a generous amount of compost. Use our compost calculator to work out how much you need.

Cucumber — outdoor varieties (ridge cucumbers) can be planted out in late May. Plant into rich soil, 60cm apart. Greenhouse cucumbers can go into their final positions in a heated greenhouse from early May.

Peppers and chillies do best in a greenhouse or polytunnel in the UK, but in southern England they can crop outdoors in a warm, sheltered spot. Harden off thoroughly and plant 45cm apart.

Broccoli, cauliflower, Brussels sprouts and cabbage — transplant seedlings started in March and April to their final positions. Space broccoli and cauliflower 60cm apart, Brussels sprouts 75cm apart. Firm the soil well around each plant — brassicas need a solid root hold to support their weight later in the season.

Maincrop potatoes go in during May. Plant 12-15cm deep, 37cm apart in rows 75cm apart. Varieties like Maris Piper, Desiree and King Edward are reliable maincrops. They will be ready to harvest from late August to September.

Preparing new beds for all these transplants? Our soil calculator tells you exactly how much soil you need.

Quick Wins: Fastest Crops to Start in May

• Radishes — still the champion, ready in 4 weeks. Sow in gaps between slower crops.
• Rocket — baby leaves in 3 weeks from a May sowing. Grows even faster in warm soil.
• French beans — sown directly outdoors in mid-May, cropping from July. One of the best value-for-space crops.
• Lettuce — cut-and-come-again leaves in 4 weeks. Sow in part shade now, as hot May sun can cause bolting.
• Courgettes — planted out in May, first fruits in 6-8 weeks. Extraordinarily productive.

Flowers to Plant in May

May transforms the garden. With the frost risk fading, you can fill beds, borders, hanging baskets and containers with colour. This is the month for the big planting-out push.

Tender Bedding Plants

After the last frost (mid to late May), plant out all tender bedding: petunias, geraniums (pelargoniums), begonias, lobelia, fuchsias, busy Lizzies and salvias. These are the backbone of summer containers and hanging baskets. Always harden off for a week before planting — even a light frost will kill them.

Hanging baskets planted in May and kept in a greenhouse for two weeks will be fully established and flowering when you hang them outside in early June.

Direct Sowing Outdoors

Sunflowers — if you have not already sown these in April, May is your last good chance for giant varieties. Sow where they will grow, 2cm deep, against a wall or fence for support.

Nasturtiums sown now will flower from July. They are brilliant for containers, for trailing over walls, and the flowers are edible. Cosmos can still be sown directly outdoors in May — they will catch up quickly in the warm soil and flower from August.

Bulbs and Tubers

Dahlia tubers can be planted outdoors from mid-May after the last frost. Plant 10-15cm deep and 60cm apart. Stake tall varieties at planting time. Dahlias will flower from July until the first autumn frost — they are the single best value cut flower you can grow.

Gladioli — plant the last batch now for flowers in September. Successive planting from March to May gives you gladioli from July through to October.

Fruit in May

May is about establishment and protection rather than new planting for most fruit. The focus shifts to ensuring this year's crop develops well.

Strawberries will be flowering now. Keep the soil moist and mulch around plants with straw (or bark mulch) to keep the developing fruit clean and off the ground. Net against birds — they will strip a strawberry bed overnight. Use our mulch calculator to work out how much you need.

Fruit trees — if you did not thin apple fruitlets in late May, do so once the natural "June drop" occurs. Remove any damaged or diseased fruit to channel the tree's energy into fewer, larger apples.

Container fruit — blueberry bushes and citrus trees can go outdoors from mid-May. Place in a sunny, sheltered spot. Water regularly and feed with an ericaceous fertiliser for blueberries.

Rhubarb — stop harvesting rhubarb by the end of May (or early June at the latest). The plant needs to rebuild its reserves for next year. Leave all stems to grow and feed the crown through summer.

Regional Planting Adjustments

May is the month where regional differences really matter. The difference between a frost-free garden in Devon and an exposed plot in the Scottish Highlands can be 3-4 weeks.

The golden rule: if frost is forecast, keep tender plants indoors or cover them with fleece. A single May frost can destroy weeks of careful nurturing. Many experienced gardeners wait until the bank holiday weekend at the end of May before committing tender plants to the open ground.

Common May Planting Mistakes

1. Planting out before the last frost. The most common and most devastating mistake. One cold night will kill tomatoes, courgettes, beans, peppers and squash. Wait until you are confident the frost risk has passed — or keep fleece at the ready.
2. Skipping hardening off. Plants raised indoors need at least 7-10 days of gradual exposure to outdoor conditions. Put them outside during the day and inside at night. Transplant shock from skipping this step sets plants back by weeks.
3. Planting courgettes too close together. They grow enormous. Each plant needs at least 90cm of space. Three courgettes planted 30cm apart will produce a congested, disease-prone mess. Two plants spaced 90cm apart will outperform five plants crammed together.
4. Not watering transplants enough. May can be warm and dry. Newly transplanted seedlings need consistent moisture for the first 2-3 weeks while their roots establish. Water at the base of the plant, not over the leaves, and water in the evening to reduce evaporation.
5. Forgetting to support climbing crops. Runner beans, climbing French beans and sweet peas all need supports. Install these at planting time, not three weeks later when the plants are flopping over. A sturdy support structure makes harvesting easier too.

Frequently Asked Questions

Where to Buy Seeds and Plants in the UK

Ready to plant? These UK suppliers stock seeds, plug plants and everything you need for May planting.

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Useful Gardening Tools

Planning your May planting? These free calculators help you work out exactly how much you need.