Gardening tips for May
Now is an exciting time in the gardening calendar – we’re in the thick of spring, meaning (if you’re lucky), the last of the frost has passed and warmer weather has finally arrived. There is so much fresh growth and planting that you can enjoy this month, as well as plenty of jobs to keep you busy in the garden.
Flowers begin to bloom, bringing bright new colours to admire, and trees and shrubs show off their luscious green leaves. The gradual transition from into the warmer seasons is our favourite reason to get outside and tackle those tasks and get your outdoor space ready for summer.
Our Green Team’s top tips:
Once you’re certain there won’t be any more frosty mornings or nights, you can start mowing your grass as usual – about once a week. Follow our guide on getting your lawn summer ready.
Make sure you check for nesting wildlife before clipping hedges, mowing long grass, and pruning shrubs.
On warmer days, remember to ventilate your greenhouse to regulate the temperature and humidity levels and encourage healthy plants.
What can I do in my garden in May?
Keeping on top of general garden maintenance this month helps create an environment that will allow your plants to thrive, and be more enjoyable to spend time in. Plus, it means when the nicer weather comes along, you’ll be ready to make the most of your outdoor space!
Now we’re getting into summer, regular weekly mowing is best for a perfect summer lawn. You can mix any grass clippings into your compost heap, too.
Early May is an ideal time to sow new lawns or repair bare patches on soil that has been prepared, levelled, and firmed. Make sure to keep it well watered and avoid walking on it for a few weeks to allow time for the new roots to establish.
Remove any early spring bedding, like pansies and violas, to make way for fresh summer displays.
Warmer temperatures usually encourage weeds to burst into growth – the quickest and easiest way to control them is to hoe before they have a chance to establish. Applying a thick layer of mulch over the soil surface helps prevent any further weeds from growing.
Deadhead clumps of daffodils and tulips so that energy is concentrated back into the bulb for next spring’s flowering.
Early season plants, such as pulmonarias, hardy geraniums, or forsythia, can be cut back after flowering to encourage the re-growth of tidy, fresh new foliage and often a stunning second flush of flowers.
If your hedges are looking a little shaggy, this is a month to give them a light trim.
In May, cottage garden plants will be growing quickly and can fill your outdoors with untamed growth. Plant supports should be put in place around your plants to help hold heavy stems or blooms of flowers, such as peonies and sweet peas.
Protect young seedlings and susceptible lush foliage plants, like hostas, from slugs using granules or barrier pellets.
Flowers to plant this month
May is the month is to plant your summer bedding plants. With busy lizzies, begonias, and petunias, bedding plants cover every area and fill every gap in your garden. Plant your favourite flowers in your patio, containers, hanging baskets, window boxes, beds and borders for a vibrant display of colour right through summer. Read our guide on how to plant flowers in a pot, container, or window box for more tips.
As well as beautiful bedding plants, there are lots more glorious plants and flowers you can add to your outdoor space to bring it to life as we transition into summer.
Roses, peonies, and gladiolus are some of the best flowers to plant in May. Roses and peonies will fill your garden with sweet summer fragrances, while gladiolus is ideal for adding to cut flower bouquets.
Hydrangeas are another ideal hardy plant for garden beds and large pots. Plant them in May and come next month you’ll have delicate flowers in shades of pink, white, and even blue.
Depending on your location and weather, tender plants including cannas and dahlias can be planted out towards the end of the month, too. Be sure that any new plants are kept watered during dry, hot spells.
Flower seeds to sow in May:
Cornflowers (this is your last chance to sow!)
Sunflowers
Zinnias
Primrose
Wallflowers
Pansies
Daisies
In beds and borders
Any bedding plants you’ve raised from seeds indoors can be hardened off over a period of 7-10 days in cooler conditions before being planted outside.
For quick and easy results, fill gaps in your borders with late sowings of hardy annuals, or plant groups of late summer flowering annuals such as cosmos or nicotiana for added colour and fragrance.
In pots and containers
Bedding plants are versatile and can be used to brighten up outdoor pots, troughs, window boxes, and hanging baskets – pick your favourite and start potting up!
There’s still time to plant lavender in containers in May if you haven’t done so already. Planting lavender in containers means you can move it around your garden wherever and whenever you’d like. Sit it next to a doorway or somewhere it’ll catch a light summer breeze, so its rich floral scents are carried through your garden and home.
Remember to feed containers and hanging baskets fortnightly with a liquid fertiliser – particularly your spring flowering bulbs that will still have life left, like tulips.
Any permanent plants in your pots and containers should be top-dressed with mulch and compost, as this gives them the organic matter they need to grow their best.
What fruit and veg can I grow in May?
Most vegetable crops can be sown in May, such as salads and spinach which can provide you with a consistent supply of fresh leaves. If you have empty space in your border, fill it with rows of your favourite herbs, such as parsley and coriander, for a plentifully supply.
Continue earthing up your early potatoes to prevent tubers being exposed to the light and turning green. Earthing up just means continuing to cover up shoots with soil as they grow.
If you have not done so already, plant main-crop potatoes this month for a ready-to-harvest supply from late summer into autumn. Read our potato growing guide for more detailed advice.
If you’ve been germinating tomato seeds, then these can be planted outside from early May (as long as the frosts have passed). Make sure to harden off seedlings and young plants first before permanently moving them outdoors.
Start to harden off courgettes and cucumbers, too, ready for planting out in June.
Begin to plant out strawberry runner plants in outdoor beds, hanging baskets or pots – but only if the weather is warm enough.
Put netting up around soft fruit plants to protect them from birds. If necessary, you can also tie growing stems of runner beans to support sticks.
Later in the month, you can harvest any previously planted stems of rhubarb and asparagus spears at their tastiest and most tender. You can also harvest any grown lettuce, radishes, or rocket.
Fruit and vegetable seeds to sow in May
Cucumber
Main crop carrots
Broccoli
Swede
Beetroot
Peas
Spring onions
French and runner beans
Sweetcorn
Courgettes
Pumpkins
Looking after wildlife this month
As the weather warms, it’s important we give pollinating insects, birds, and other wildlife a helping hand with food, water, and shelter.
Hang birdfeeders in your trees, and clean bird baths so that any feathery friends visiting your garden has access to food and water.
If you would like a wildlife lawn that encourages birds, insects, and other animals to visit, then leave your grasses to grow longer throughout the summer.
Continue planting flowers for pollinators, such as coneflowers, lavender, and other various wildflowers. These help pollinating insects like bees and butterflies, which are vital for our ecosystem.
The transition into summer is one of the most beautiful times of year, so we’d love to see what you get up to this May, whether you’re curating an indoor garden or making your lawns look pristine!
Make sure to take a picture and tag us on socials @dobbiesgardencentres for your chance to be featured on our channels. If you’re looking for more advice, pop into your local Dobbies and ask a member of our Green Team for help.