May is when UK gardening properly gets going. The soil has warmed up, the days are long, and there’s a full season still ahead. If you’ve been waiting for the right moment to get started, this is it.
There’s a lot you can plant in May — both sowing seeds directly outside and getting tender crops that have been growing indoors moved out into the garden. The catch is that May has two halves. Early May still carries a frost risk in many parts of the UK, particularly in the north, on higher ground, and in known frost pockets. Late May is a different story, and the window opens up considerably once that risk has passed.
This guide covers the vegetables, seeds, and flowers worth planting in May in the UK, along with what’s still better kept indoors for now. For the full year overview, When to Plant Vegetables in the UK and for everything else worth doing in the garden in May beyond planting May Gardening Jobs in the UK. If sweetcorn is on your list this season, When to Plant Sweetcorn in the UK covers exactly when to sow and when it can safely go outside.
Vegetables to Sow Directly Outside in May
May is one of the best months of the year for direct sowing — putting seeds straight into prepared beds outdoors. The soil is warm enough for reliable germination, and anything you sow now has months of growing weather ahead of it.
Carrots are one of the best veg to sow in May. Germination is far more consistent now than in the cold, wet soil of early spring, and you’re much less likely to get patchy rows. A lot of gardeners sow a short row every couple of weeks through May and into June rather than doing it all at once — it spreads the harvest and avoids a glut. When to Plant Carrots in the UK has the full regional timing.
Beetroot is one of the most dependable May sowings there is. It germinates quickly in warm soil, grows without much fuss, and is genuinely forgiving if you’re still finding your feet. When to Plant Beetroot in the UK covers the detail if you want it.
Peas can still go in during early May, though the window starts to close as the season warms up. If you haven’t sown any yet, get them in now. When to Plant Peas in the UK explains what to expect from later sowings.
French beans and runner beans can be sown outdoors from mid-May, once the soil has warmed properly and overnight temperatures have settled. Any earlier and the seeds tend to just sit there — or rot. It’s one of those crops where a bit of patience in May pays off in June. When to Plant French Beans in the UK and When to Plant Runner Beans in the UK are both worth a quick read before you sow.
Lettuce, salad leaves, spinach, and spring onions are among the easiest things you can sow in May. They’re fast, low-maintenance, and you can be harvesting within a few weeks. If you’re new to growing, these are great confidence-builders.
Potatoes can still go in during early May, particularly maincrop varieties in cooler northern areas where planting earlier wasn’t possible. If you’re in the south, first earlies may already be in the ground — but it’s not too late. When to Plant Potatoes in the UK covers the full timeline by variety and region.
Tender Crops to Plant Out in May
If you’ve been growing tomatoes, courgettes, cucumbers, or squash indoors since March or April, May is when they start moving outside. But not all at once, and not before they’re ready.
The step that makes the biggest difference is hardening off — gradually getting plants used to outdoor conditions over a week or two before leaving them out permanently. Move them outside during the day and bring them back in at night to start with. Plants that skip this step often sit there doing nothing for weeks, even when the weather looks fine. It’s worth doing properly.
Tomatoes are usually ready to go outside from late May, once overnight temperatures are consistently above 10°C. In a greenhouse or polytunnel, you can do it earlier. Rushing tomatoes out in early May is one of the most common mistakes of the month — they look okay for a few days and then stop. When to Plant Tomatoes in the UK covers the timing in full.
Courgettes can go outside from mid to late May in milder, sheltered gardens — but late May or early June is more sensible in the north or in exposed spots. One cold night can set them back badly. How to Grow Courgettes in the UK covers everything from sowing to harvest.
Cucumbers go outside from late May, but only in genuinely warm and sheltered spots. They’re more sensitive to cold than courgettes and often do better kept under cover in the UK. When to Plant Cucumbers in the UK will help you decide whether outdoor or indoor growing suits your space better.
Growing in containers rather than open ground? The same rules apply — tender crops need warm nights before they go outside, whatever size pot they’re in. Can You Grow Vegetables in Pots in the UK? covers what works well in containers through the season.
Flowers to Plant in May in the UK
May is also a good month to get flowers in the ground, whether you’re growing them alongside vegetables, in borders, or in pots. For the full breakdown of what flowers to sow and plant out this month, What Flowers to Plant in May in the UK covers every option in detail. Hardy annuals like nasturtiums, cornflowers, and calendula can all be sown directly outside now and will flower through summer. They’re easy from seed and nasturtiums in particular are almost impossible to fail with.
If you want to plant out bedding that was started indoors — such as cosmos, marigolds, or antirrhinums — wait until the risk of frost has passed in your area before putting them outside permanently. The same hardening-off process that applies to tomatoes and courgettes applies here too.
Nasturtiums are worth a special mention if you’re growing vegetables too — they’re useful companion plants that attract aphids away from other crops and bring in beneficial insects.
Still Worth Starting Indoors in May
Not everything needs to go outside this month. Leeks are ideally started indoors or in a seedbed in May for planting out later in summer. They’re a long-season crop and starting them now keeps the whole timeline on track for an autumn and winter harvest. When to Plant Leeks in the UK covers the full schedule.
Brassicas for autumn and winter — kale, purple sprouting broccoli, and Brussels sprouts — can also be started under cover in May for planting out in June. They’ll be in the ground for months, so it’s worth reading When to Plant Brassicas in the UK to get the spacing and timing right from the start.
Watch for Frost and Slugs
Frost catches people out in May every year. A clear, still night in the first two weeks of the month can drop temperatures enough to damage tender plants that went out too soon. If you’re not sure when your last frost typically falls, UK Last Frost Dates by Postcode is worth checking. And if frost is forecast after you’ve already planted out, How to Protect Vegetables from Frost in the UK covers what you can do quickly.
Slugs are the other May problem. Mild, damp evenings after spring rain are perfect conditions for them, and young seedlings are most vulnerable in the first few weeks. If they’re a persistent issue in your garden, How to Get Rid of Slugs in the Garden covers the methods that actually work.
Once seedlings are up, don’t skip thinning them. Crowded seedlings compete badly for light, water, and nutrients and rarely produce good crops. When to Thin Vegetable Seedlings in the UK explains how to do it without pulling out the ones you want to keep.
FAQs
What vegetables can I plant in May in the UK?
Carrots, beetroot, peas, French beans, runner beans, lettuce, spinach, and spring onions can all be sown directly outside in May. Maincrop potatoes can also go in during early May in many parts of the UK. Tender crops like tomatoes and courgettes can go outside from late May once frost risk has passed and they’ve been hardened off.
What can I sow in May in the UK?
May is one of the best months for sowing outdoors. Carrots, beetroot, peas, French beans, salad leaves, and spinach all germinate reliably in warm May soil. Hardy annual flowers like nasturtiums and cornflowers can also be sown directly outside this month.
Can I still plant potatoes in May in the UK?
Yes — particularly maincrop varieties and in cooler northern areas where earlier planting wasn’t practical. Early May is still within the planting window for most UK gardens. See When to Plant Potatoes in the UK for guidance by variety and region.
Is it too late to plant tomatoes in May in the UK?
No. Late May is actually the most common time to plant tomatoes outside in the UK. Planting too early in cold conditions causes more problems than waiting for the weather to settle properly.
What flowers can I plant in May in the UK?
Hardy annuals like nasturtiums, cornflowers, calendula, and sunflowers can all be sown directly outside in May. Tender bedding plants like marigolds and cosmos can go outside from late May once frost risk has passed in your area.
A Sensible Place to Start
May has more planting options than almost any other month in the UK. Hardy veg like carrots, beetroot, and salad leaves can go straight in the ground now. Tender crops like tomatoes and courgettes follow from mid to late May once conditions are right. And if you want flowers too, hardy annuals like nasturtiums can go in right alongside your vegetables.
The trap most people fall into is rushing. Getting things outside too early, sowing into soil that hasn’t warmed properly, or skipping the hardening-off step all slow things down rather than speed them up. A slightly later start in the right conditions nearly always beats an earlier one that struggles.
If you’re not sure where to begin, pick two or three things rather than trying to do everything at once. Beetroot, lettuce, and French beans are all solid May sowings — fast results, low risk, and a good foundation for the rest of the season.For a more detailed guide to sowing seeds specifically, What to Sow in May in the UK covers every crop with sowing depths, spacing, and timing. And if you have tender plants ready to go outside, How to Harden Off Plants in the UK explains the two-week process that stops them stalling when they go out.