Gardening tips for May
May is an exciting month with lots of fresh growth and plants to enjoy, as well as plenty of exciting new jobs to keep you busy in the garden. Beautiful blooms begin to open, meaning bright new colours to admire, and trees and shrubs burst into leaves. Containers are ready to be refreshed with vibrant bedding plants in readiness to make the most of warmer days outdoors. It’s safe to say summer is officially on its way!
Alongside new plants to fill your outdoor spaces with, May will hopefully bring some warmer weather to make gardening this month even more rewarding. After fighting through frosts and April showers, the gradual transition from spring to summer is a great motivator to get outside and tackle those gardening tasks that you maybe weren’t able to get to during the earlier months of the year.
From bedding to seed sowing, we've pulled together some handy tips to help you make the most of your outdoors in May.
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 lawns summer ready for more tips and tricks.
On warmer days, remember to ventilate your greenhouse vents and doors to help regulate the temperature and humidity levels, which encourages healthy plants.
Make sure you check for nesting wildlife before clipping hedges, mowing long grass and pruning shrubs.
This month is all about: summer bedding
May is the month to plant your summer bedding plants. With busy lizzies (Impatiens), 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.
Our bedding plant of the month, geraniums (Pelargoniums), are popular amongst garden lovers as they provide a boost of colour throughout summer and are easy to grow and maintain. Plant geraniums in bedding displays or in pots – they look particularly beautiful growing beside lavender.
Seeds to sow in May:
Flowers
Cornflowers (last chance to sow)
Sunflowers
Zinnias
Primrose
Wallflowers
Pansies
Daisies
Fruit & vegetables
Cucumber
Main crop carrots
Broccoli
Swede
Beetroot
Peas
Spring onions
French and runner beans
Sweetcorn
Courgettes
Pumpkins
Flowers to plant & grow in May
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. And, depending on your location and weather, tender plants including cannas and dahlias can be planted out towards the end of the month too. Just make sure that any new plants are kept watered during dry, hot spells.
In beds & borders
Any bedding plants you’ve raised from seed indoors can be hardened off over a period of 7 to 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 & containers
Bedding plants are versatile and can be used to brighten up outdoor pots, troughs, window boxes and hanging baskets – pick your favourites 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 wherever it will 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 – this gives them the organic matter they need to grow their best.
Fruit & veg to grow in May
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 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.
Most vegetable crops can also be sown now. If you sow quick-growing crops such as salads and spinach every 10 days, you’ll get 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 plentiful supply perfectly suited for summer salads and al fresco barbecues. If you’re short on space, grow herbs in containers on your patio, balcony, or windowsill for easy picking as you need them.
Begin to plant out strawberry runner plants in outdoor beds, hanging baskets or pots, only if the weather is warm enough. Put up netting around soft fruit plants to protect them from birds. If necessary, you can also tie growing stems of runner beans to plant 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.
May lawn care
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 or bins if you have them 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.
For a lovely, even greener lawn, apply a high nitrogen summer feed.
Indoor gardening
The 12–18 May is Mental Health Awareness Week. Did you know tending to plants is a great way to practice mindfulness? It can even promote relaxation and reduce stress levels. If you don’t have a large garden, keeping houseplants in your home is just as effective. So, if you’re looking for some exotic new indoor greenery, discover our collection of houseplants. There’s something for every person and every space. If you’re already a houseplant parent, May is a great time to repot your indoor plants which will help invigorate their growth.
If you’ve been growing plants indoors, continue pricking out half-hardy and tender seedlings. When they are large enough to be planted out, be sure to harden them off in a cold frame over a period of 7 to 10 days before planting outside in their final position.
General maintenance
Planting flowers and growing your own fruit and veg is exciting, but it’s also important to look after your plants, and the rest of your garden, properly. Keeping on top of general garden maintenance helps create an environment that will allow your plants to thrive in. Plus, it means when the nice weather comes along, you’ll be ready to make the most of your outdoor space. Whether you’re taking advantage of a dry bank holiday weekend or have a few hours spare in the afternoon, here are some priority gardening jobs you can get done in May:
Early spring bedding like pansies and violas will be starting to fade now, so remove these to make way for fresh summer displays. You can add them to your compost heaps and bins for homemade compost.
Warmer temperatures will encourage weeds to burst into growth. The quickest and easiest way to control them is to hoe them before they have the chance to establish. Applying a thick layer of mulch over the soil surface helps prevent any further weeds from growing. Mulching with organic matter also locks in moisture and, over time, helps to improve your soil, all while giving plants a well-needed boost.
Deadhead clumps of daffodils and tulips so that energy is concentrated back into the bulb for next spring’s flowering. Leave the foliage in place to die back naturally. 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. More tender late summer flowering shrubs such as caryopteris, salvia, and hardy fuchsias can also be trimmed now so they remain bushy and full of life all season.
If your hedges are looking a little shaggy, this is a good month to give them a light trim.
In May, cottage garden plants will be growing vigorously 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 or sweet peas. Do this early, before your plants get too big, and the look will be more natural. Once they’re established, they’ll start to climb happily by themselves.
Protect young seedlings and susceptible lush foliage plants, like hostas, from slugs using granules or barrier pellets.
Look after wildlife
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 any feathery friends visiting your garden have 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.
Continuing planting, or if you haven’t started planting already, flowers for pollinators, such as coneflowers, lavender and various other wildflowers. These help pollinating insects like bees and butterflies, which are vital for our ecosystem. You could also have a go at creating a bee bath for an environmentally friendly feature in your garden. It’s super easy to make and it provides bees with easy access to water to keep them healthy and busy. All you need are some terracotta pots and planters, plus some small rocks.
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. While you’re there, don’t forget to explore our full range of plants and gardening products to ease you from spring into summer. Keep an eye on our inspiration page for more things you can do to enjoy the season and prep your garden for the months to come.