May Gardening Jobs

There’s something special about gardening in May, when birdsong fills the air, the garden is brimming with possibility and summer feels just around the corner. Whether you’re planting summer flowers, sowing vegetable seeds or simply keeping on top of the essentials, it's a beautiful time to immerse yourself in the rhythm of your garden and watch it flourish.

May is perhaps my favourite month in the garden. It's warm and light enough to spend evenings pottering around planting, weeding and watering, and my garden feels full of energy and life. You can also take advantage of the two long weekends to tackle some larger projects in your garden. If your front garden is in need of a little TLC, get some inspiration from these 33 Front Garden Design Ideas.

Whether you have a large garden, a compact urban space or a few containers on a patio or balcony, you can always find room for one more plant. Read my May Flowers blog post to find out what you can plant for flowers in May.

In warmer parts of the country, you may already be hardening off your tender plants in preparation for planting them out. I usually wait until the end of May, and as I don't have a greenhouse, for three weeks or so, my main hobby becomes moving plants into and out of my house. Once they're planted out, I can relax a bit, but there's still plenty of watering and other plant care jobs to do. Here are your checklists of gardening jobs for May!

 

Flowers, shrubs & trees

In warmer parts of the country, you'll be able to harden off your tender plants and move them into their final positions this month. As spring flowers begin to fade, you can replant your containers and hanging baskets with summer bedding plants. However, the nights can still get very cold in other parts of the country, where it may be better to hold off planting out until next month.

What to plant in May in the UK

What flowers to plant in May:

• Plant out sweet pea plants. Like edible peas, sweet peas need a support structure to scramble up. Pea sticks or netting work well. Put your supports in place before planting.

• Harden off and plant out summer bedding plants such as petunias, lobelia, pelargoniums and begonias once the risk of frost has passed.

• In warmer areas, you should be able to harden off and plant out dahlias and cannas in the second half of the month.

• May is the perfect time to fill gaps in your beds and borders while the soil is still moist. You can plant new herbaceous perennials, potted evergreen and deciduous shrubs like hydrangeas, and climbing plants. Perennials that prefer warm, dry conditions, such as lavender and salvia, are best planted in spring rather than autumn.

What seeds to sow in May:

• You can direct sow tender annuals, such as cosmos, nasturtiums, sweet peas and sunflowers, outdoors now, as the soil should be warm enough for the seeds to germinate.

• You can still sow hardy annuals this month; they'll just bloom a little later. Sprinkle poppy and cornflower seeds in any gaps in your beds for late summer flowers.

• It feels early to be sowing seeds for next year, but biennials, such as wallflowers, foxgloves, and Sweet William, need to be sown in the next couple of months, so they can grow into strong young plants before winter. You can sow seeds outdoors in May in milder regions.

• Plant winter pansy seeds from this month to grow your own winter bedding plants. 

What bulbs to plant in May:

• It's time to plant your dahlia tubers outdoors! The soil should be warm enough in May, even in colder parts of the country, and by the time shoots appear, the weather should be warm enough that they won't need extra protection. Tubers planted outdoors this month will flower a little later than those started indoors earlier in the year, but they'll quickly catch up, and you'll still get months of flowers.

• You can also plant gladioli corms outdoors this month. Individual gladioli bloom for about two weeks, so stagger your planting if you want a longer display of flowers.

• Plant out any other summer-flowering bulbs you've been hanging on to. Late-flowering plants still have plenty of time to grow and bloom.

Propagating and dividing

• May is the perfect time to take softwood cuttings from hardy and tender perennials and deciduous shrubs. Softwood cuttings root quickly and easily. Take cuttings from new, non-flowering shoots and cut just below a leaf node. Remove lower leaves and dip the base of the cutting in hormone rooting powder before inserting it into a pot of cutting compost. Keep the pot in a warm, moist environment with moderate light.

• Keep an eye out for self-seeded seedlings in your beds. If you don't want them to grow in situ, you can pot them up and move them to a different part of the garden.

• Lift and divide large clumps of daffodils once the foliage has turned yellow and died back. It's best to do this every three or four years to make sure they keep flowering.

• Divide overcrowded primroses and pulmonaria once they've finished flowering. Lift each plant and tease the clump of roots apart, replanting sections in the ground or in pots.

Pruning and cutting back

• Continue deadheading tulips, but leave the foliage to die back naturally.

• Cut back faded Aubrieta and Alyssum after flowering.

• Prune early-flowering Group 1 clematis if necessary, once the risk of frost has passed.

• Lightly prune evergreen ceanothus and other spring-flowering shrubs once they've finished flowering.

• "Chelsea chop" late-flowering perennials in late May to create a neat shape and prevent the plants from becoming leggy. Suitable perennials include sedums, asters, echinacea, rudbeckias, heleniums and phlox. You may choose to leave some plants untrimmed to flower earlier.

• Remove any damaged, frost-blackened growth from tender plants.

General maintenance

• Tie in new shoots produced by climbing plants, including roses, clematis and honeysuckle. Train the shoots to grow horizontally on walls or around vertical supports to ensure you get flowers along the length of the stems.

• Forget-me-nots are beautiful, but they spread easily. Remove any that are in the wrong place before the flowers turn to seed.

• Put stakes or other supports in place for peonies, lilies, delphiniums and other tall perennials.

• Keep on top of pests: check for vine weevil, aphids and red lily beetles.

• Unless we've had a very dry spring, May is when watering begins in earnest. Water in the evening or morning and make sure you use rainwater for acid-loving plants like blueberries, rhododendrons and azaleas.

• Feed plants in containers every few weeks.

• Feed spring bulbs once they've finished blooming to help the bulbs store energy for next year.

 

Fruit and vegetables

May is a major sowing and planting month in the kitchen garden. While it can be tempting to plant all your seeds at once, succession sowing ensures a longer harvesting period and means you won't lose your entire crop if you're hit by an unseasonably late frost. You may also be able to harvest your first spring crops this month, which is a welcome reminder of the reason for your efforts.

What vegetables to plant in May

• Sow warm-weather crops such as squashes, courgettes, cucumbers, peppers, beans and melons indoors for the best chance of germination. If your vegetable garden is a sun trap and the nights aren't too cold, you may be able to sow directly outdoors towards the end of the month.

• Root vegetables can be sown outdoors, though beetroot may benefit from cloche protection if the soil is still cold and wet.

• Continue sowing peas and mangetout outdoors for a longer harvesting period.

• You can sow sweetcorn outside, though be prepared to protect young seedlings on cold nights. Plant sweetcorn in blocks, not rows, to help with pollination.

• Keep sowing salad crops like lettuce, rocket and spinach, and Oriental leaves at intervals to get a continuous harvest.

• It feels a long time until Christmas, but if you want Brussels sprouts for your festive meals, you need to sow them this month, along with cabbages and cauliflowers. You can start them off indoors or sow them outside.

• In most parts of the country, you can harden off and plant out some of your seedlings this month. The exact timing will depend on your local weather – check the long-range forecast and, if in doubt, wait a week or two, particularly with tender plants like tomatoes and peppers.

Harvesting

• Established rhubarb plants should give you a good harvest. Remember to pull the stems away from the crown rather than cutting them. Add the leaves to your compost heap.

• Fast-growing radishes should be ready to harvest this month. Don't let them get too big, as they can turn woody.

• Pick young spinach and chard leaves for salads.

• May is the peak month for harvesting asparagus. Cut the spears when they're about 15 cm long, just before cooking them.

• Your globe artichokes may look small, but this is the best time to pick and cook them whole. 

• This is likely to be the final month to harvest your spring cabbages and cauliflowers.

Fruit bushes and trees

• Remove weeds from around fruit bushes while they're small.

• Check gooseberry and currant bushes for sawflies and aphids and remove any you find.

• Thin out the developing fruits on your gooseberry bushes to leave space for the remaining fruit to grow. You can cook the unripe fruit and use it in jams and chutneys.

• Raspberries throw out lots of suckers at this time of year. It's best to remove most of them, so your canes don't get too crowded.

• If you remove the flowers from new (first year) strawberry plants, this helps your plants establish a strong root system, so you get more fruit in subsequent years.

• Check apple and pear trees for canker, scab and mildew.

• Open the doors of fruit cages to allow insects to pollinate your plants.

• Place nets over strawberries and soft fruit bushes to keep the birds away from your fruit. I save plastic bottles and place them upside down on top of garden canes to support the netting.

General maintenance 

• Water seeds and seedlings, along with fruit bushes, trees and other crops grown in pots.

• Try to keep on top of the weeding. It does sometimes feel like a never-ending challenge, but do your best!

• Keep an eye on the forecast for late frosts and have cloches or fleece to hand to protect tender seedlings. If you get caught out, you can use bubble wrap or even newspaper for a night or two.

• Continue earthing up your potatoes so the tubers don't get exposed to light.

 

Lawns and hedges

May is the peak growing month for grass and hedging, so if you want a neatly trimmed lawn, you'll need to keep on top of the mowing. Alternatively, embrace No Mow May and let part or all of your lawn grow long to encourage wildflowers, bees and butterflies into your garden.

• Mow lawns regularly to maintain a traditional look.

• Edge lawns for a crisp finish, creating a "gutter" to prevent grass from getting into your flower beds.

• Add grass seed to any bare patches in newly sown lawns. Wait until the grass is at least 5 cm tall before walking on it.

• If you need to feed your lawn, choose a slow-release spring lawn fertiliser.

• Mowing paths through your lawn lets you create space for wildlife while still having a usable lawn. For larger spaces, you could mow a maze or create a piece of living lawn art! This is also a good compromise if you want to encourage bees into your garden, but you don't want to risk young kids stepping on them.

• Late spring is a good time to prune evergreen hedges, but only if you won't be disturbing wildlife. This is unlikely to be an issue with small topiary and formal hedges, but you may have to leave larger hedges until after the nesting season has finished.

 

Other garden jobs for May

You may be too busy looking after your plants this month to do much else, but if you have a few spare moments, there's always more work to be done. May is a good time to plant up existing ponds and create new ones.

• Add aquatic plants to pond margins and bog gardens once water temperatures rise.

• Divide established pond plants, such as waterlilies.

• Remove blanket weed and duckweed using a stick or net. Rather than throwing it away, leave it on the side of the pond for a couple of days to let any creatures caught in the weeds escape.

• Little and often is the best way of weeding gravel paths and patios to keep them neat and tidy.

• Greenhouses can really heat up this month on sunny days. Make sure you have a shading system in place, such as blinds, or paint the outside of the glass with shade paint. Don't forget to open doors and windows for ventilation.

• Take advantage of fine weather by smartening up your fences or shed with a lick of paint.

• Dust off your garden furniture and give it some TLC – hopefully you'll be getting plenty of use from it over the coming months.

 

FAQ

What can I plant in May in the UK?

In many parts of the UK, you can harden off and plant out tender plants such as dahlias, cosmos, marigolds and tomatoes this month. May is also a great time to sow tender and hardy flower seeds and vegetables, including carrots, parsnips, sweetcorn, radishes, lettuce and chard, outdoors. Take advantage of our spring sales to fill gaps in your borders with perennial plants and shrubs.

Can I cut my hedge in May?

May is peak nesting season, so before carrying out any hedge work, check carefully for nesting birds. Major hedge cutting is often better timed outside the bird nesting season, but you may be able to trim small, formal hedges. For more information on cutting hedges, read our guide to hedge trimming.

When is it safe to plant out tender plants in May?

This depends on your location. In mild, southern areas, you may be able to plant out certain plants at the beginning of May, while colder northern or exposed gardens may need to wait until late May or the start of June. Check the last frost date for your area on PlantMaps. Don't forget to harden plants off before moving them outdoors.