Here’s some advice about what to consider for your garden during May.
General tasks and garden maintenance gardening in May
Look out for late frosts and keep vulnerable plants and new shoots protected at night if frost is forecast.
Don’t be tempted to put out tender bedding until the middle of the month and even then be prepared to cover it if necessary.
Continue with the spring cleaning. Hoe your borders to get rid of weeds before they take hold – ideally on a dry day. Dandelions are a nuisance at this time of year – if you don’t have time to deal with them terminally, chop their heads off before they set seed.
Water thoroughly once or twice a week rather than little and often – however, containers will need watering every day.
Mulch away before the herbaceous growth really takes off. Use your garden compost or leaf mould, the contents of out-of-date grow bags, ready-made soil conditioner or well-rotted manure.
Now the soil is beginning to warm up and things are starting to grow, add general purpose fertiliser before covering with mulch especially in borders, the fruit and vegetable patch and containers.
Remove moss and weeds from paths, terraces and drives and keep an eye out for pests around the garden. Try to keep the use of chemical controls to a minimum – they may kill off pests, but they also kill off the beneficial insects that prey on them such as ladybirds.
It’s time to tackle slugs and snails. Protect tulips, shoots of delphiniums and the like, by using pet-friendly slug pellets, drench the ground around hostas with liquid slug killer to exterminate slugs below the surface.
Trees, shrubs and climbers
Trees or shrubs planted in the last couple of years on lawns or in areas of rough grass should have a circle of clear earth around them as grass will prevent essential moisture getting through. Mulching with bark or compost will help.
Clematis should now be growing – tying the new stems in regularly will prevent a tangle of new shoots, which can break easily.
Prune forsythia and ribes – flowering currant.
Cut a proportion of the oldest, tallest stems right down to the base.
Twist off the spent flower heads of rhododendrons and azaleas and mulch with composted bark, garden compost or leaf mould after watering if the ground is dry. Feed with an acid feed.
Feed acid loving plants such as camellias and rhododendrons with ericaceous feed if you are on neutral or alkaline soil.
Spray roses with fungicide to ward against black spot and mildew and repeat every fortnight until autumn. If an infection sets in, all the stricken leaves must be burnt. Do not leave them on the compost heap as this will become the perfect incubation site.
Lawn mowing is a priority. Try to mow weekly as it the lawn is left too long between cuts the job becomes much harder.
May is the last chance to sow a new lawn this spring.
If you are unsure how to make a new lawn, ask for help and advice from a garden centre.
Bulbs, flowers and containers
Protect new spring shoots from frosts and slugs. Deadhead narcissi and tulips as they go over, and sprinkle with bonemeal or liquid feed. Allow them to die down naturally before clearing away the foliage, lifting and splitting towards the end of the month.
Erect supports for herbaceous plants such as peonies, delphiniums and oriental poppies. Make your own supports using hazel or birch twigs for a natural look that will fade into the border as your plants grow.
Sow nasturtiums, calendula and poppies in drifts – plant taller plants behind shorter ones. Tie in sweet peas using sweet pea rings or soft twine. Remove tendrils and sideshoots – this will result in longer stemmed flowers.
Summer bedding is now available in garden centres as young plants for you to grow. Make sure pots and containers don’t dry out, especially if they are near a wall and in a sheltered position.
Plant up tubs, containers, and hanging baskets. Harden tender plants off properly before exposing them to the elements.
Water regularly in dry weather.
Plant strawberry plants in the ground, in planters or in hanging baskets for your summer crop. Protect fruit trees and gooseberries with netting to prevent birds consuming your crop.
Look out for caterpillars and pick them off as soon as you see them.
It’s time to harvest your rhubarb – enjoy a delicious rhubarb crumble or rhubarb fool.
Garden centres are now full of young plantlets of vegetables, salads and herbs. For those that find growing from seed daunting, this is a great solution. Be cautious about planting them straight outside, and ask your garden centre for advice.
Many vegetable crops can be sown as seed this month – check the instructions on the packet. Broad beans, carrots, lettuces, spinach, salad leaves, leeks and chard are healthy, cheap food options. Sow salads in short runs every fortnight to ensure a continuous crop. Don’t sow entire packets of seed in one go to avoid a glut.
Sweet peppers, tomatoes, aubergines and salads can be planted in your greenhouse and can be purchased at a garden centre.
Earth up potatoes – draw the soil up to a ridge over the plants when they are six inches tall.
Repeat one month later and then again two or three weeks later to prevent sunlight getting to the tubers, which turns them green and makes them poisonous.
Pinch out broad bean tips to discourage blackfly. Erect a surround of canes connected by string to support the plants when they produce pods.