What to plant in May – the best flowers, herbs and vegetables to grow

There is lots of choice for what to plant in May, and with summer just around the corner it gives us all extra incentive to get out into the fresh air and busy planting.

May is an exciting and busy time in any garden. You can start to plant out summer bedding, harden off half-hardy plants, take cuttings and prune as well as keep on top of weeding. 

Keep an eye on weather forecasts though, while you're planning your garden ideas, and protect tender plants and seedlings with fleece or cloche if late frosts are forecast. 

What to plant in May – vegetables to sow or plant

As the weather begins to warm up, there are a host of crops that can be sown as part of your vegetable garden ideas. 

If you're tight on space, then choose wisely when deciding what to plant in May and, where possible, try to ensure you'll have successional crops to harvest.

1. Sweetcorn

'Tender sweetcorn thrives in warmer environments and, once May comes around, usually the risk of all frost has passed,' explains gardener Mr Mitford, who looks after the kitchen garden at Hawkstone Hall. 

In cooler areas, plant out sweetcorn under glass in cold frames or the greenhouse. In the warmer areas you can sow sweetcorn seeds out directly in the prepared ground as part of your raised garden bed ideas.

'As sweetcorn is wind pollinated, plant it in block formation rather than rows to ensure good pollination,' adds Mr Mitford.

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2. Tomatoes

Start growing tomatoes from this month by planting in grow bags or borders in the greenhouse.

Tomatoes are a good crop for vegetable container garden ideas and even if you don't have a greenhouse, they can be grown elsewhere under cover. Bush varieties are an attractive option to grow on windowsills and in conservatories, and tall cordon varieties can also be grown indoors if there is the space and light.

Plant plug plants 18in (45cm) apart, or two per growing bag and add supports for climbing varieties as they will grow quickly.

They are hungry plants, so you need to make sure tomatoes get enough nutrients and water, 'so always plant them deep in their grow bags, containers or beds,' advises Kris Collins, nursery manager at Thompson & Morgan.

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3. Squash

Winter squash and pumpkins need 3 to 4 months of warm weather to produce a worthwhile crop, so are an excellent choice for what to plant in May. You need to sow the seeds under cover from now to harvest from August.

Squash come in a range of shapes and sizes, and can be grown as climbers so are ideal if space is more limited, or for vegetable garden trellis ideas.

Sowing under cover is better in colder regions, but if you live in a warmer zone, or leave it until the end of the month when the threat of frosts has passed, then you can sow the seeds direct in the ground where they are to grow.

Sow the flat seeds on their side, ½in deep, in 3in (7.5cm) pots of compost 

If you don't want to grow them from seed, 'you can also buy young squash plants from garden centers in May and these can be planted direct outdoors,' explain the RHS experts.

Buy your squash seeds at Amazon.

4. Carrots

As one of the easiest crops to master, it's definitely worth novice vegetable gardeners learning how to grow carrots.

It's no wonder that Peter Rabbit was always trying to steal Mr McGregor's crops because a freshly pulled carrot from your home plot tastes so much better than even the best quality organic varieties you can buy in stores. 

Sow maincrop carrots  directly in the ground outdoors from May. Sow the seeds at every three week intervals so that you can enjoy a continuous supply of this crunchy veg. 

Make shallow trenches about ½in (1cm) deep, spaced about  6–12in (15-30cm) apart. Sow carrot seeds thinly in the trenches about 2- 2½ inches (5-8 cm) apart.

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Salad and herbs to plant in May

For continuous harvesting throughout summer, start salad and herb crops now for delicious light lunches in warmer weather.

1. Lettuce

If you're wondering how to grow lettuce, you'll be pleased to hear that 'lettuce crops thrive in the warm days and cool evenings of spring,' explains Mr Mitford.

Sow lettuce seeds  ½in (1cm) apart, leaving 11in (30cm) between rows. 

'Make sure to water the lettuce plants regularly. If you position the lettuce around taller plants, this will offer them some relief from the summer sun,' he adds. 

Buy your lettuce seeds from Amazon.

2. Cilantro – coriander

You can sow coriander, or cilantro seeds directly into the ground or into containers from May.

It is easy to learn how to grow cilantro from seeds or from cuttings, and if you sow at monthly intervals this will ensure that you have a continuous crop for adding flavor to many dishes, from soups and curries, to refreshing salads.

Coriander is a good choice for herb garden ideas, inside or outside, as its aromatic leaves are so versatile for their culinary uses.

Buy your cilantro seeds from Amazon.

3. Dill

Dill is another good choice for what to plant in May, and can be sown direct into the ground in a herb garden or vegetable plot, or in a herb planter.

Opinion is divided on whether dill is easy or tricky to grow, with some experienced gardeners claiming they sometimes struggle with how to grow dill. But if you  plan carefully and give the plants the attention they need, you will be rewarded for your efforts with the tasty, fennel flavored feathery leaves. 

Dill is also excellent for companion planting with other crops in the kitchen garden as its flower umbels attract beneficial insects that feast on pests – a much more eco-friendly garden idea than using harmful pesticides.

Sow dill seeds thinly outdoors in a sheltered, sunny position, in rows ½in (1cm) deep, into well prepared soil.

Buy your dill seeds from Amazon.

Flowers to sow in May

'I remember someone saying to me, "May is like a party where the dress code is green. And that’s certainly true where we live,' explains expert plantswoman Sarah Raven.

With the arrival of lighter evenings, and the end to frosts, it’s peak flower planting time, so there are plenty of ideas for what to plant in May.

‘It should be warm enough to think about direct sowing flower seeds straight into the garden and if, like mine, your soil is heavy clay, some can also be sown in gutters or modules and then planted out,' she adds.

1. Cerinthe major ‘Kiwi Blue’ – honeywort

'The usual cerinthe is one of my all-time favorite border fillers and for cut flower foliage, but ‘Kiwi Blue’ is even better, bigger, smokier and more purple,' says Sarah.

The seeds are tough, so they are best soaked for 12 hours and then direct sown in a sunny spot, or in a gutter. They will then flower this year. 

'If sowing direct in the ground, sow the seeds as thinly as possible. Remove the seedheads if you do not want this cerinthe to self-sow. If you are using the cut flowers for vase arrangements, then to prolong flowering, sear the stem ends in boiling water for 10 seconds to make them last,' Sarah adds.

Don't miss these Blue Honeywort Seeds from FlowerSeedsGalore147 at Etsy.

2. Nasturtium ‘Black Velvet'

Once you have learned how to grow nasturtiums, you can add this rich and glamoros deep colored variety to the mix.

'Grow for ground cover in your border or in a container and the edible petals are good in salad,' explains Sarah.

Nasturtiums make a great choice for companion planting in a vegetable garden as they lure pests away for the crops

'Sow the seeds direct into the garden, two seeds per spot, spaced 30cm apart, and thin to one. Once established, nasturtiums need very little attention,' advises Sarah.

'If you feed them you will gain leaf at the expense of flowers, and too much watering will give the same result,' she adds.

Don't miss these Nasturtium Black Velvet seeds from Eden Brothers.

3. Cosmos bipinnatus ‘Rubenza’

'Even if you only have a small garden – or just some pots – you have to grow at least one cosmos. They are the lowest maintenance, floweriest plants in the world,' enthuses Sarah. 

Cosmos are perfect if you're planning a cut flower garden as it is a classic cut-and-come-again flower as well as a lovely garden plant. 

'In reward for very little effort, they give you buckets of cut flowers – and they have a very good vase life, too,' says Sarah.

One of Sarah's favorites, Cosmos bipinnatus ‘Rubenza’ opens very dark, like crimson velvet, and then brightens as the flowers develop. Their egg-yolk-yellow centers are stuffed full of nectar and pollen, so as soon as the sun comes out, they’re heaving with butterflies and bees,' so make an excellent choice for adding the flower bed along with other wildlife garden ideas.

'Direct sown in the garden in early May, they should flower in August,' adds Sarah. 'Pinch out tips for bushier plants and stake if needed.' 

Don't miss these Cosmos Bipinnatus Rubenza seeds from Eden Brothers.

What is best to plant in May?

There is an endless list of vegetables, salads and herbs that you can plant in May, along with many flowers. Keep an eye on the weather, though, as you need to make sure the threat of frost has passed before you sow or plant out many of the choices.

When planning a kitchen garden, make sure that you will have a succession of crops, so the trick is not to plant everything at once, but rather space out the sowing and planting so that crops will be ready t o harvest at different times, ensuring as long a harvest period as possible.

What should I do in my garden in May?

There is a long list of jobs you can do in the garden in May. With summer just around the corner, May is an exciting and busy time in any garden. 

Just some of the tasks include:

• Plant out summer bedding
• Harden off half-hardy plants
• Take cuttings from tender perennials
• Tie in climbing plants, to vertical supports to encourage them to grow upwards, such as if you're growing sweet peas
• Harden off dahlias that were potted up in early spring, and other tender plants, by bringing them outside during the day to acclimatize, and plant out once threat of frost has passed
• Prune spring flowering shrubs after blooming, such as forsythia, viburnum and lilac, so that they can put on new growth for next year’s display
• Weed beds and borders weekly with a hoe or by hand to prevent weeds from establishing and taking nutrients from your flowers