Gardening in May: what to plant and tidy in your garden this month
May is one of the richest times of year for gardeners; with lush seasonal vegetation, flowers swamping borders and outdoor spaces being capitalised on as the weather improves.
With the month drawing on, it’s finally time to get ahead with gardening jobs in preparation for summer.
Here are our tips on jobs that you can start with to improve your garden space. Good luck!
Gardening jobs to do in May
Irisis
Elegantly flowered Iris versicolor ‘Algonquin’ flowers in May and June in shallow pond edges and bogs. Tor Garden Plants sells it and a large range of unusual and beautiful water irises to plant now.
Harden off dahlias
Around mid May, I start to harden off my dahlias so that they are ready to be planted outside at the end of the month. This year’s great new hope is Dahlia ‘Jomanda’ and ‘Karma Fuchsiana’, both of orangey salmon colouring, and both also available now as pot plants from pheasantacreplants.co.uk, should you have failed to get around to starting tubers earlier.
Cacti and succulents
Cuttings of succulents take easily at this time of year. Pull off a leaf of an echeveria or a pachyphytum and set it aside to callous over for a few days, then push it gently into very gritty compost. Soon tiny growths will appear and you will know it is rooted.
Net gains
Just draping nets over fruit bushes is a path to accidentally trapping birds: invest in a proper fruit cage from northernpolytunnels.co.uk or make small cages from batons of wood and net that you can lift off for harvesting.
Meadow land
If you sowed a small patch of meadow in late autumn or early spring, thin it now, wherever seedlings have germinated in thick patches, to allow a few inches between each one. You will get bigger and healthier plants.
Globe artichokes
This is the globe artichoke’s moment. Steam for 30min, or until the leaves come away easily, and dip into melted butter and lemon juice. Remove winter mulch protection from around plants, feed, water and mulch with compost or manure.
Pinch beans
Pinch out broad beans as soon as flowers appear to keep black fly at bay, and give the plants some support if they are leaning. I push a cane into the ground at the end of each row and stretch some twine between them.
Currant affairs
Now that flowering currants are over, ensure good flowering next spring by cutting the flowered shoots back to a strong young shoot further down the stem. Cut out about a third of the oldest stems completely.
Selection of tomatoes
If you plan to plant your tomatoes into pots, consider vintage long tom pots from long-toms.co.uk. These are made with drainage holes in the sides and should be slightly buried. The roots then escape the pots and search for moisture. The modern day equivalent are Grow Rings, available on Amazon.
Also in May… Beautiful brute
Now Clematis montana has finished flowering it is a good time to give it a haircut, before it swamps your shed. Shear it all over for a tidy-up, or cut it back hard if need be. It will be fine, though you may get fewer flowers next year.
Spuds you’ll like
Now is the time to earth up your potatoes to prevent them from turning green. You should also make sure to plant any that may still be lingering at the bottom of sacks or in egg boxes.
Eucalyptus leaves
Eucalyptus trees that have got out of hand can work beautifully as a coppiced shrub, and this is the time to do it. Chop yours to the ground now and you will soon see a flush of new glaucous foliage. You can repeat every few springs.
Rocks away
It’s time to plant up new alpine troughs and rock gardens. First add lots of drainage to the base, then make a half-grit, half-compost mix. Visit Border Alpines to browse a wonderful selection of plants.
Chillies
We are so used to nipping out the tips of plants to make them bushy, but chillies don’t need it. Keep pinching fingers away or you can delay first fruit by up to a month. A range of plants is still available from seaspringplants.co.uk, although orders have been delayed until mid-May.
Beetle mania
Look out for viburnum beetle larvae, which can badly defoliate plants. They are pale yellow with black markings and active now, so if you spot tattered leaves lift them and deal with the culprits.
Cutting edge
It is asparagus harvest time and if you believe you can never have too many special garden tools it is time to arm yourself with an asparagus knife, for its long curved blade. There is a beautiful one at worm.co.uk.
Bumblebee on lavender
If you didn’t trim lavender plants after flowering last year, do it now. Take shears to them and remove all of last year’s old flowers, before giving the whole bush a very light trim all over in order to promote bushy growth.
Stock up now
Penstemons benefit from being pruned back now. Last year’s growth has now done its job and protected them all winter, and as you chop you can take softwood cuttings and increase your stock. Each cutting should be about 4-5in long.
Carefully remove the bottom two pairs of leaves then insert several cuttings into a pot of compost, water and cover with a clear polythene bag and place in a greenhouse or on a windowsill until they have rooted.
Leggy fig
My fig tree has grown leggy and gappy in the middle, and this is the time to cut it back to stimulate more growth from the base. Not the whole plant, but a branch or two cut down to the base should promote a flush of new stems.
Remove heads from faded daffodils this month
Remove heads from faded daffodils and tulips. They will be better next year if they can throw their energy into feeding their bulbs rather than producing seed. Tying up the stems looks daft – allow them to die down naturally.
Carrot and stick
Late April to late May is the time when carrot flies are on the wing, so if you sow direct in the next month, be sure to immediately cover your rows with horticultural fleece to ward them off.
Planting out broad beans into a raised bed
If you have struggled to keep up with vegetable sowing this spring, help is at hand in the form of Delfland Nurseries’ plug plants, which can be bought by mail order ready to plant out.
May’s offerings would normally be the most numerous of the year, since this is the prime month for getting your patch planted. However, the nursery is only taking new orders for June delivery onwards in order to catch up with a backlog (organicplants.co.uk).
Caring comfrey
Comfrey is high in nutrients and easy to make into a great – if whiffy – organic fertiliser. Buy plants now of ‘Bocking 14’ (a sterile variety and so not as invasive as some comfrey) from organiccatalogue.com
Strawberry pots
If you have strawberries growing in pots, bring some of them into the greenhouse. This will bring on early growth and flowers, as long as you leave the greenhouse door open so that pollinators can visit.
For later
Chrysanthemums make wonderful late-summer cut flowers. I buy rooted cuttings of ‘Allouise Orange’ for planting out as soon as frosts have passed (chrysanthemums direct.co.uk).
Wade, lift, tip
If your waterlilies were lacking in flower last year, it may be time to divide. Wade in, lift, tip from its planting basket and then use a knife to divide the rhizomes, making sure each has a young shoot. Then replant each in its own basket and place back in your pond.
Box blight
Look out for signs of box blight. If you see afflicted areas, cut them out and dispose of away from the garden. Feed the afflicted box plant well, keep it watered all summer and don’t trim it, and there is a small chance it may outgrow the problem.
