May Planting Guide: Best Flowers, Herbs, and Vegetables to Grow

May brings a wealth of options for planting, energizing us to enjoy the outdoors and cultivate our gardens.

This month is bustling for gardeners. It's time to plant summer flowers, harden off tender plants, take cuttings, prune, and manage weeds.

However, stay alert to weather forecasts and protect delicate plants with fleece or cloches if late frosts threaten.

What to Plant in May – Vegetables to Sow or Plant

As temperatures rise, various crops can be sown in your vegetable garden.

If space is limited, make thoughtful choices about what to plant in May. Aim for a staggered harvest by selecting crops that mature at different times.

1. Sweetcorn

'Tender sweetcorn loves warmth, and by May, the frost risk is usually gone,' says Mr. Mitford from the kitchen garden at Hawkstone Hall.

In cooler regions, start sweetcorn in cold frames or greenhouses. In warmer climates, sow seeds directly into prepared soil.

'To ensure good pollination, plant sweetcorn in blocks instead of rows,' he suggests.

Find sweetcorn seeds at Amazon.

2. Tomatoes

Start planting tomatoes this month in grow bags or greenhouse borders.

Tomatoes are perfect for container gardening, and even without a greenhouse, they can thrive in sheltered spots. Bush varieties work well on windowsills, while taller cordon types need support.

Space plug plants 18 inches apart, or place two per grow bag, ensuring ample nutrients and water by planting them deep, advises Kris Collins from Thompson & Morgan.

Purchase tomato seeds at Amazon.

3. Squash

Both winter squash and pumpkins require 3 to 4 months of warmth, making them ideal for May planting. Start seeds undercover now for an August harvest.

Squash come in various shapes and can be grown vertically, making them perfect for limited spaces or trellising.

While sowing undercover is best in cooler areas, if you're in a warmer zone or sow late in the month, you can plant seeds directly.

Plant flat seeds sideways, ½ inch deep, in 3-inch pots of compost.

If you prefer not to start from seed, young squash plants are available in garden centers this month, ready to plant outdoors, say RHS experts.

Buy squash seeds at Amazon.

4. Carrots

Carrots are among the simplest crops to grow, making them perfect for beginners. A fresh carrot from your garden is far tastier than store-bought varieties.

Sow maincrop carrots outdoors from May, spacing seeds every three weeks for a continuous harvest.

Create shallow trenches about ½ inch deep and 6 to 12 inches apart. Sow seeds thinly, 2-2½ inches apart.

Purchase carrot seeds at Amazon.

Salads and Herbs to Plant in May

Start planting salad greens and herbs now for fresh summer meals and flavors.

1. Lettuce

Lettuce flourishes in the warm days and cool nights of spring, making May the perfect time to sow.

Plant lettuce seeds ½ inch apart, with 11 inches between rows.

'Regular watering is crucial. Positioning lettuce near taller plants provides shade during hot summer days,' notes Mr. Mitford.

Find lettuce seeds from Amazon.

2. Cilantro – Coriander

Sow cilantro seeds directly into the soil or containers in May.

Learning how to grow cilantro is easy, and sowing monthly will ensure continuous fresh leaves for soups, salads, and more.

This aromatic herb is perfect for indoor or outdoor gardens due to its versatility in cooking.

Buy cilantro seeds from Amazon.

3. Dill

Dill can be sown directly into a vegetable plot or herb garden this month.

Some find growing dill challenging, but with proper care, it rewards you with flavorful leaves.

Dill attracts beneficial insects, making it a great choice for companion planting in your garden.

Sow dill seeds thinly in rows ½ inch deep in a sunny, sheltered area.

Purchase dill seeds from Amazon.

Flowers to Sow in May

'May is like a celebration of green,' notes plant expert Sarah Raven.

With longer evenings and the frost threat fading, it's prime time for flower planting. Direct sow flower seeds into the garden or use gutters/modules if needed.

1. Cerinthe major 'Kiwi Blue' – Honeywort

'Cerinthe is one of my favorite plants for borders and cut flower arrangements,' says Sarah, highlighting 'Kiwi Blue' for its vibrant color.

Soak seeds for 12 hours before sowing in sunny spots or gutters for earlier blooms.

Thinly sow seeds directly, and remove seedheads to prevent self-sowing. For cut flowers, sear stem ends in boiling water for longevity, she adds.

Check out Blue Honeywort Seeds from FlowerSeedsGalore147 at Etsy.

2. Nasturtium 'Black Velvet'

Once you master growing nasturtiums, this deep-hued variety makes a stunning addition.

'Use them for ground cover or in containers, and their edible petals add flair to salads,' Sarah explains.

Nasturtiums are excellent for companion planting, deterring pests from crops.

Sow seeds directly, spacing two per spot and thinning to one. They require minimal care once established, but too much fertilizer leads to more leaves than flowers.

Find Nasturtium Black Velvet seeds from Eden Brothers.