May garden tasks: the complete checklist from last frost to summer

May: when the garden finally takes off

May is the month gardeners wait for all year. The risk of frost fades away, daylength is generous, and the soil is warm enough for almost everything. It is also the month where months of planning and preparation come together. The difference between a well-tended May garden and a neglected one will be visible all summer long.

There is a natural rhythm to May. The first half is about patience and preparation, the second half about planting with abandon. Here is everything you need to tackle, roughly in order.

The Ice Saints and last frost dates

In Northern Europe, the period from 11 to 15 May is traditionally known as the Ice Saints (IJsheiligen in Dutch, Eisheilige in German, Saints de glace in French). These are the last dates when night frost can reasonably be expected in most of Western Europe. It does not happen every year, but when it does, tender plants are destroyed overnight.

The practical rule: do not plant anything frost-tender permanently outdoors before 15 May. This includes:

• Tomatoes, courgettes, peppers, aubergines and other warm-season crops started indoors
• Bedding plants like geraniums, fuchsias, begonias and petunias
• Dahlias that have been started in pots
• Tender herbs such as basil

If you have already bought these plants, stand them outside during the day in a sheltered spot and bring them in at night. After the 15th, plant freely.

Hardening off seedlings

Seedlings raised on a windowsill or in a greenhouse need a transition period before they can cope with outdoor conditions. This process, called hardening off, takes about seven to ten days.

Start by placing them outside for two hours in a sheltered spot on a mild day. Each day, increase the time and exposure. By the end of the week, leave them out overnight if no frost is forecast. This step prevents transplant shock and sunburn on leaves that have never experienced direct sunlight or wind.

Direct sowing outdoors

May is prime time for direct sowing. The soil temperature is high enough for rapid germination and there is still plenty of moisture. Sow these directly where you want them to grow:

• Vegetables: runner beans, French beans, beetroot, carrots, lettuce, radish, sweetcorn, courgette (after mid-May)
• Herbs: dill, coriander, parsley, chives, basil (after mid-May)
• Flowers: sunflowers, cosmos, marigolds, cornflowers, nasturtiums

Mark your rows with sticks or labels. Water gently with a fine rose on the watering can to avoid washing seeds out of position. Keep the soil moist until germination.

Lawn care: the first proper cut

Grass grows explosively in May. This is the time to establish a good mowing routine:

• Mow weekly but keep the blade at 4 cm or higher. Scalping the lawn leads to brown patches in summer
• Edge the borders with a half-moon edger or powered edger. Clean edges transform the look of the entire garden
• Feed with a spring lawn fertiliser if you did not do so in April
• Overseed bare patches by raking the soil lightly, scattering seed and pressing it down. Keep moist until established

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Weeding while the going is good

The soil is still soft from spring rain, which makes weeding far easier now than it will be in July when the ground bakes hard. Concentrate on:

• Bindweed and ground elder: pull out as much root as possible; these are persistent and need repeated attention
• Dandelions: use a long-handled weeder to extract the entire taproot
• Creeping weeds like clover and chickweed: rake and remove thoroughly
• Paths and patios: pour boiling water into joints or scrape manually; avoid chemical weedkillers

After weeding, mulch your borders with a 5 to 7 cm layer of garden compost, bark chips or cocoa shells. Mulch suppresses new weed growth, retains moisture and feeds the soil as it breaks down.

Staking tall perennials

Delphiniums, peonies, phlox and rudbeckia grow rapidly in May. If you wait until they flop over after a heavy rain shower, it is too late to stake them neatly. Install supports now, while the plants are still growing into them.

Metal ring supports that the plant grows through look far more natural than individual canes with ties. Place them when the plant is about a third of its final height.

Deadheading spring bulbs

Tulips, daffodils and hyacinths are finishing their show. The faded flowers look untidy and the temptation is to cut everything back. Resist that urge. Remove the spent flower heads by snapping or twisting them off, but leave the foliage intact. The leaves are busy photosynthesising and sending energy back to the bulb for next year's flowers. Only remove the foliage once it has turned completely yellow and limp, usually by late June.

To disguise the dying foliage, plant perennials nearby that will grow up and hide it. Hardy geraniums, lady's mantle and ornamental grasses work beautifully.

Filling hanging baskets and containers

After the Ice Saints, containers and hanging baskets can be planted up with summer bedding. Use quality potting compost with slow-release fertiliser mixed in. Some reliable combinations:

• Full sun: pelargoniums + trailing lobelia + silver-leaved Helichrysum
• Part shade: fuchsias + begonias + trailing ivy
• Contemporary: ornamental grass (Carex) + Heuchera + Calibrachoa

Water containers daily in warm weather. They dry out far faster than borders and the plants will suffer quickly without regular watering.

Pond maintenance

May is a good time to check the pond after spring:

• Remove blanket weed with a stick or rake
• Add new oxygenating plants like hornwort or pondweed
• Check pumps and filters are running properly
• Start feeding fish lightly as they become more active
• Reintroduce water lilies if you overwintered them indoors

Pest patrol

May marks the start of the pest season. Keep a close eye on:

• Aphids: check rose tips, perennial shoots and vegetable crops. A strong jet of water dislodges them, or spray with diluted soft soap
• Slugs and snails: set beer traps, scatter coffee grounds around vulnerable plants, or lay tiles for them to shelter under and collect them each morning
• Box tree moth: inspect box hedges for webbing and caterpillars. Prune out affected sections and consider biological control with nematodes
• Lily beetle: bright red beetles on lilies and fritillaries. Pick them off by hand daily

Pruning spring-flowering shrubs AFTER they finish

A common mistake is pruning spring-flowering shrubs before or during their bloom. Plants like forsythia, flowering cherry, hawthorn and Spiraea flower on wood produced the previous year. Prune them immediately after flowering so they have the rest of the season to produce new flowering wood for next spring.

For forsythia, cut the oldest stems right to the base. For flowering cherries, limit yourself to dead wood and crossing branches.

Feeding roses

May is the ideal time to feed roses. Apply a specialised rose fertiliser or a mix of well-rotted manure and blood meal around the base of each plant. Water in well afterwards.

Also remove any suckers growing from the rootstock. You can identify them by their different leaf shape, typically seven leaflets instead of five. Pull them away from the rootstock with a sharp tug rather than cutting, to discourage regrowth.

Keeping on top of it all

May can feel overwhelming. There is so much to do and it all seems urgent. My advice: tackle one job per session and finish it properly before moving on. By the end of the month, you will have a garden ready for a spectacular summer.

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