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In the Garden : May

The month of May is with us, with longer days and (we hope) more heat in the sun. So far, spring has been reasonably kind to us, though we have a few late frosts to cause us worry. Let’s take a look at what we need to do in the garden this month.

May Gardening Calendar


We are into weekly mowing now with the mower blades set at their regular height. 

Time now to think about nutrition to support your lawn through the summer. Look for a ‘slow-release’ fertilizer in your garden centre to deal with this right through the summer. You can get a combined ‘weed and feed’ product too if broad-leaved weeds are a problem on your turf. Pick a dry day to apply, but with rain forecast later in the week.

The Flower Garden 

May has arrived, but there is still the chance of night frost, so make sure any summer bedding placed outside to ‘harden-off’ is not damaged. Place plants in the greenhouse of frame or cover them with horticultural fleece. You can start planting out the more hardy annuals later in the month.

Flowers to plant in May

Maybe you have directly sown some hardy annuals like alyssum, calendulas and cornflowers last month? If not, there’s still time this month. Thin out any crowded seedlings to give them growing space.

It may seem a long way in advance, but May’s the time to be sowing biennials like sweet william’s and wallflowers to flower next spring.

Biennial and perennial flowers will be well into growth in the herbaceous border. Make sure tall plants have the appropriate support through to flowering time and don’t forget the fertilizer to aid growth.

You will be busy with bulbs in May. Plant summer flowering items like dahlias, gladioli, and lilies. Remove the foliage from spring-flowering bulbs once they have ‘built the bulbs’ for next season. Lifting to clear space for summer bedding? Dry the bulbs off and store them in a cool, dry place prior to replanting in the autumn.

The Vegetable Plot

Vegetables to plant in May

There’s still time to sow cucumbers for outdoor growing, by starting them indoors and planting resulting plants outside in early June. Sweet corn can be sown directly outdoors but better results are often obtained by sowing in pots and planting out later.

Successional sowings outside of summer salads should be in full swing, to ensure continuity of items like leaf salads, lettuce, radish and beetroot, through the summer. Make sure you ‘thin out’ crowded seedlings to the required spacings to ensure plants mature properly.

You may well have started your runner beans in pots indoors or directly outside. If not, there’s still time, but you need to be quick about it! Try one of the new runner/French types like Firestorm (red flowered), or Moonlight (white-flowered).

Early planted potatoes will be growing fast now. Earth them up with soil to encourage the production of new tubers, increasing the crop yields.

Finally, there’s plenty to do, but you also need to think about next year by sowing cabbages and broccoli bred for winter and spring harvesting.

The Fruit Patch

On the strawberry plot, fruit will be ripening. It’s the ideal time to ‘straw-down’ the area. This involves laying down straw from last year’s corn harvest under the fruiting trusses. This suppresses weed growth and protects the ripening fruit from fungal diseases.

Trees & Shrubs

Plant growth can really be accelerating at this time of year. Keep an eye on climbing and rambling roses. It’s important to tie in shoots before they get out of hand – it will save you so much time as the year progresses! Similarly, new shoots of early flowering clematis can get very overcrowded and will need training and support.

Certainly in the south and midlands, March has been a relatively dry month. It’s a good idea then to mulch around shrubs with garden compost or well-rotted garden manure, to add nutrients, but also to conserve moisture around the plants.

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