Planting guide for May

Sowing the seeds for your future harvest

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Becky Alton
Productive Grower at The Lost Gardens of Heligan, Cornwall
10 May 2022

This month we speak to the ever-knowledgeable Becky Alton who is one of the gardeners at the Lost Gardens of Heligan and our guru for all things green-fingered. Becky explains which crops and plants are best for planting in the month of May, and shares with us all of those little tricks and tips you wish you knew before you started gardening.

A busy time of year

“Traditionally, April and May are the two months of the year which have been known as the ‘hungry gap’ which is often the hardest time of the year for UK farmers and growers.

This is because it’s the transitional time when we switch from harvesting any left-over crops from the previous year, and starting to sow the seeds again this year. April brings with it a hefty ‘to do’ list for gardeners as we turn our thoughts towards realising all the early summer planting dreams we planned during those long winter months.

Beetroot

This is the time when temperatures are on the rise and the soil will be warming up ready for direct sowing. However, don’t be tempted to move too quickly as a hard frost could wipe out all your seedlings. If your beds are ready-prepped, here are a few ideas for crops which can be sowed directly during May…

Mark out a straight row and if the soil is dry, pre-water the drill (shallow trench). Sow the seed thinly, around 1 inch in depth. The little seedlings should start to appear after approximately 14 days. This is the best time to thin the seedlings to around 4 inches apart.

Top Tip: When thinning seedlings make sure that you thin them as soon as possible. I usually look for the true leaves to appear and then I know it’s time. If you sow a few short rows every 14 days, this will help provide you with a continuous crop.

Heritage varieties

I love heritage beetroot; a feast for the eyes as well as the palate! A few of my favourite heritage varieties include:

Bulls Blood Beetroot
This variety has an intensely dark red leaf and the foliage can be treated like “cut-and-come again” ( cutting away the mature leaves to let young leaves continue to grow or allow new growth to form and mature). Once the roots are ready, they produce a delicious salad beet.

Chioggia Beetroot
This old Italian heirloom variety is named after the fishing village near Venice where they were first grown. Chioggia boasts an eye-turning red and white pattern which, when sliced, adds a decorative style to any salad.

Lettuce

Homegrown lettuce is both more flavoursome and more economical than buying bags from the supermarket and gives you a delicious variety of colour and flavour. Cut-and-come-again loose leaf lettuce make the best use of container space and will be easier to maintain. To sow the seeds, first create a shallow drill, 1 cm deep, and sow your lettuce seeds thinly.

Top Tip: If you sow the seeds in the late afternoon, it allows germination to happen in the cooler temperatures of the night. Lettuce has a tendency to “bolt” in hot weather – meaning it will go to seed and produce bitter foliage. To help prevent this, it’s important to mulch around the plants and keep the roots wet. If your area is prone to frost, place some fleece over the bed at night and remove in the morning, this will keep the soil that little bit more protected

Squash, pumpkin and courgette

Mine are looking rather full at the moment, but if you have a windowsill that is free (or are lucky enough to have a greenhouse), then May is a good time to start sowing squash, courgettes and pumpkins – my favourite things to grow!

There are so many interesting shapes and sizes of the Cucurbit family you can grow, and some varieties store well into winter months. They are also great for the kids to grow for Halloween carving. First, prep some 9 cm pots with compost and place a seed within. It’s important to ensure that the seed isn’t lying flat as this can cause the water to puddle on top when you water and rot the seed.

Tips for planting

Planting your squash and courgettes outside can be done around late May /June depending on your area. Ensure you have incorporated lots of well-rotted manure or grow bag compost into your planting hole. These plants are hungry and enjoy lots of nutrients.

Top Tip: Bury a terracotta pot next to the plants roots when they are in situ – this will help with watering as water in the pot will channel it directly to the roots, so no water is wasted to the hot soil.

Potatoes

The first early potato seedlings of the year may need earthing up now. I usually wait until they have grown to around 10-15 cm in height. Gently cover the shoots with the soil from either side of the plant, minding you don’t disturb or damage the planted potato seed.

Earthing up is encouraging your potato to grow more delicious potatoes but be careful not to expose any tubers as this will cause greening, and green potatoes are poisonous. Planting out of your Second early potatoes and maincrops can be completed in April, these will need earthing up later on.

Floral planting

I always plant flowers which not only look beautiful, but will be beneficial for the early appearing bees. The most common bees you will see first appearing in spring are the solitary bees, who live alone as the name suggests, and there are almost 200 solitary bee species in the UK. They are crucially- important pollinators for fruit trees and other food crops, and they will be buzzing about looking for early nectar.

Having a diverse planting scheme will attract different types of bees as each species has a different tongue length, making them able to feed from different-shaped flowers depending on their tongue.

Supporting wildlife

The common garden bumblebee (bombus hortorum) has one of the longest tongues in the bee species and they love to eat nectar from deeper more trumpet-shaped flowers such as foxgloves (Digitalis) or honeysuckles (Lonicera). Some other types of flowers to plant for these amazing pollinators would be alliums, bluebells, wallflowers, lavender, myosotis (forget-me-not) and pulmonaria.

Some easy flowers that you can sow directly that are beneficial to insects include borage, nigella and cosmos – some of these will also self-seed and come back year after year. Lots of flowers will also serve to attract a bounty of other beneficial pollinators and insects such as hoverflies, butterflies and ladybirds which are all crucial to help maintain a healthy ecosystem in your garden.