May marks the switch into summer. Everywhere things in the gardening will be coming to life. Don’t be in a rush to move patio pots and hanging baskets outside though. Check when the last frost date is in your area as you can safely move tender plants outdoors after this. The same goes for tender veg, such as courgettes and sweetcorn. May is the month where the cooler, wetter days of spring have ended. The temperature is rising, and the warmth of summer is just around the corner.
1. Stake and care for perennials
May is the time to get going with perennials as the ground is warm and they’ll start growing more quickly. Only plant out the ones that can stand a little frost, but if your garden is generally frost-free, tender plants such as dahlias can be put out too.
Keep mulching before the plants grow too much and you can still get in between them and see what you’re doing.
Stay on top of the weeds if you can. A quick hoe once a week will keep them at bay and will mean they don’t compete for water, light, or nutrients with the plants you want to grow.
Buy extra plants if you need an easy fix. Little plugs of sweet peas are handy for slotting into any spot where they’ll have something to climb up and will give enormous joy as the year goes on.
Perennials put on a lot of growth in May, so keep an eye on your plants and tie them in to supports as they grow, or you can insert ready-made supports around them. Doing so will save any heartbreak later down the line when windy weather could snap the stems before they come into flower.
2. Water anything newly planted
Any veg or flowers planted this spring will need regular watering while it settles in and puts down roots into the soil, especially during dry weather. This also applies to any new turf you may have laid.
3. Feed and deadhead tulips
You can encourage your tulips to flower again next year by feeding them with tomato feed and removing any flowers that have faded. Bulbs in pots are best removed from the pots after they have finished, and then replanted deeply (around 15cm deep) in the border. Ones that are left in their pots tend to produce lots of small bulbs that produce leaves, rather than flowers, in their second year.
4. Sow a wildflower patch
This is a good time to sow a wildflower patch or meadow if you have the room. Just make sure any seed mix you get is right for your soil and conditions – usually they are mixtures of less vigorous grasses and lovely wildflowers such as poppies, vetch, daisies and yellow rattle.
You don’t need a huge garden to do this, just a few square metres, and you may even want to turn over all your lawn to wildflowers. It’s much better for wildlife and is also quite low maintenance. Leave the meadow to flower and seed, then cut back in late summer.
5. Mulch strawberries
May is the month where strawberries flower and the fruit begins to form which can make a tempting feast for slugs, birds and squirrels! To protect the young fruit, add a layer of net over the plants; if you have a lot of squirrels visiting your garden, wire mesh makes a sturdier barrier. You’ll also want to protect the new fruit from the mud to prevent it from rotting; using mulch is the perfect way to do this. The most common type of mulch for strawberries is straw; place this on top of the soil around the plant.
6. Feed raspberry plants
May is a good time to feed raspberry plants as it’ll help to encourage flowering and healthy leaf growth. Floricane types (summer fruiting) respond well to tomato feed, such as Big Tom, on a weekly basis. Primocane raspberry varieties (autumn fruiting) will prefer a high nitrogen food such as sulphate of ammonia, to encourage healthy canes and leaves.
7. Get climbers growing
Secure any stems of clematis, roses, honeysuckle, or other climbing plants that are looking a little unstable. This will prevent harsh winds snapping them to make sure you can still enjoy your vertical displays when flowers blossom.
Prune early flowering clematis as the blooms fade. If your climbers have got too big for patch or pots, grab some secateurs and prune the stems above the leaf joint to maintain neatness.
Secure beautiful summer scents by planting sweet pea seedlings somewhere with plenty of sun. Use a trellis, wigwam or other method of support to help them weave up and look their best. If you didn’t manage to sow seeds earlier on in the year, buy some ready-grown plants.
8. Plant courgettes and marrows
These versatile vegetables are ready to plant into the ground in May. Prepare the soil by digging a hole around 30cm deep and 30cm wide for each plant (leave a 1m space between the holes); dig in plenty of home grown compost to improve the soil. If no frosts are predicted, you can plant out the marrow and courgette plants, but before you do, you’ll need to harden off the plants. Once in the ground, it’s a good idea to cover the plants with fleece to protect them from wind, until they’re established.
9. Sow seeds outdoors
Wondering what you can be confident about plant in May? If you plan on growing runner beans from seed, now’s the time to start planting them in the garden. When preparing the trenches, add supports so that the plants can grow up them. It’s worth adding a few extra seeds around each support just in case hungry pests eat any of the seedlings. As the seedlings begin to grow, thin out the weakest ones to allow the healthier, stronger ones to harness the nutrients in the soil.
Sweetcorn seeds can also be planted now; choose a warmish, sheltered site for these as sweetcorn are relatively delicate when growing. Always plant the sweetcorn in blocks of at least 12 plants as this vegetable is wind pollinated.
10. Hanging Baskets need to be ready
If your hanging baskets aren’t yet prepared and waiting patiently in your greenhouse, plant them up with pre-grown live plants or plugs you’ve grown on yourself. Here’s how:
Fill your basket three quarter full with compost and make holes in the compost for your plug plants.
Put the rootballs in the holes and add several scoops of feed containing water-absorbing crystals and slow-release fertiliser.
Cover the top of the rootball with compost and use your hands to gently firm up the soil around it so it’s nice and secure.
Water and then hang up in pride of place!
11. Last chance jobs
Bulbs to plant in May
With the summer nearly upon us, if you haven’t finished planting your summer flowering bulbs such as dahlia’s and gladioli, this is really the last opportunity you’ll have. Check that your bulbs are healthy and throw away any that are rotting or soft to the touch.
Sow half-hardy annuals
There’s still time to sow hardy annual seeds such as sunflowers directly where you want them to flower. Prepare the ground by removing all the weeds in the area so that the young seedlings don’t have to compete against the weeds.
Use plant protection products safely. Always read the label and product information before use.
