Keep an eye on temperatures whilst hardening off tender plants & keep your greenhouse well ventilated during warm spells. In readiness for some nice weather make sure your garden furniture is good to go & plant up your summer flowering baskets & containers to give them a chance to get established before going out when the risk of frosts has passed. There are also a range of more hardy plants which can be sown as the soil is warming up & planting summer flowering bulbs are another way of injecting colour with little effort. We have a huge range of plants & veg to choose from in the garden centre & our sowing & planting blogs & YouTube videos will give you all the information you need for a successful summer display.


Prune Lilacs flower spikes when flowering is over

  • Cut the brown sprays that have finished flowering from the lilac. This will ensure it flowers even better next year.
  • You can prune early-flowering shrubs which have finished flowering now. On varieties like Forsythia, Ribes and Spiraea cut off a few of the oldest branches every year. This constantly rejuvenates the bushes and means that they continue to bloom magnificently every year.
  • Japanese flowering quinces (Chaenomeles) can be pruned when they finish flowering which will encourage them to produce more flowering stems for next year & stop them getting too leggy - prune back to about six leaves.
  • Winter & spring flowering clematis can be pruned now if they are growing out of their allotted space. Prune back to a healthy pair of buds then train in any new shoots later on.
  • Prune winter heather that has finished flowering now.
  • It is time to trim hedges in order to prevent them from growing too vigorously. Careful not to prune any hedges if birds are nesting in them.

Planting & Sowing

Plant Sunflower seeds in May

  • You can sow sunflowers now: these big flowers are easy, fun and lovely for children. How to sow Sunflower seeds – will show you all you need to know.
  • Dahlias can be planted out at the end of the month & you can also consider planting tropical flowering plants like Canna outside now. You can continue to put in summer-flowering plants until mid-May.
  • Plant up summer hanging baskets and containers but protect from late frosts.
  • You can continue to plant evergreen shrubs and conifers until mid-May - they are sometimes supplied with the rootball in sacking. See our 
  • Plant herbs in the sunniest, most sheltered spot possible. Most kitchen herbs also grow very well in pots and troughs. 
  • Get great summer colour by planting hardy annual seeds direct into borders. Give poppies, cornflowers, ‘Love-in-a-mist' (Nigella) and marigolds a try.
  • If perennials are not showing signs of life yet, then they have not survived the winter. Replace them with new plants and enrich the soil with fertiliser and compost.
  • Dig up plants which show few signs of life, cut or divide off the young edges, replant them and throw away the old hearts.
  • Why not have a go at growing squashes have a go at growing your own pumpkins for Halloween? Now is the time to sow seeds indoors.
  • Plant some salad leaves into pots near the back door which makes them handy for continual cropping.
  • Sweet corn, runner beans and French beans can be sown directly into outdoor plots, sow under cloches in colder areas. Marrows & courgettes can be planted out at the end of the month.
  • Lettuce, peas, broad beans and radishes can all be sown in short rows for successional cropping. Although it is late to sow tomatoes, we are now stocking a range of young plants to grow on.



  • Pull up forget-me-nots after flowering. For a display next year, leave longer so plants are allowed to self-seed.
  • Guide new shoots to where you want them. In many cases they can be inserted between the existing stems, but you will sometimes have to prune in order to keep them under control and regularly tie them again.
  • Lift and divide primroses after flowering.
  • With the unpredictable weather we have been having you may need to protect your fruit blossoms with fleece including nectarines, apricots & peaches if you have a warm sunny south facing wall.
  • Stake tall growing perennials now to support new growth before they get too large & flop over. It is best not to bind bunches of stems to canes & ideally take account of the shape of the plant.
  • The grass is now growing vigorously and you will have to mow it more often. Don't forget to feed the grass, since whatever you cut and remove is a potential store of energy for the grass plants. Perennial weeds in the lawn can be treated with a selective herbicide.
  • Give your paths and patio a good spring clean with a pressure washer or wire patio brush.
  • Fertilise hedges at the roots in order to prevent them from looking elsewhere for food and competing with your other plants. Preferably use special food for hedge plants.
  • If you want to keep bulbs, they need to take up a sufficient reserve of food. That can only happen if you leave the foliage to wither slowly. Only remove it when it is completely yellowed. This applies not only to bulb crops that you want to allow to go wild, like snowbells, crocus and narcissi, but also for bulbs that you want to dig up and store, like tulips. Mow around withering bulbs in the lawn. Divide over crowded clumps of bulbs & give all your bulbs a general purpose feed.
  • Young plants in particular need regular watering. Ideally give them rainwater at the right temperature. Water caught in a water butt is perfect. When watering plants with a hose from the mains, allow the water to fall in a fine mist, giving it time to warm up a little.
  • Don't forget to keep newly planted shrubs and trees well watered too until they are well established.
  • Clear away spring bedding plants and prepare the ground for summer bedding. Harden off your summer bedding plants so that they are ready to go out when all danger of frost has passed.
  • Remove mildewed foliage from plants such as Pulmonaria. Cut to the base, water well and fresh leaves will grow.
  • Keep an eye out for pests and nip them in the bud as soon as they appear. Check gooseberries & redcurrants for sawfly larvae. You can get extra help with this by attracting birds to your garden. Not only will they visit your feeders but they will also check out your plants for tasty morsels.
  • Apply glasshouse shading or start to use blinds now. Remember to ventilate on warm days.
  • Earth up your potatoes as they grow & plant any tubers that you haven’t managed to get in yet.
  • Start to remove sideshoots from the leaf axils of cordon tomatoes.
  • Transplant brassicas such as Brussels sprouts to their cropping positions.

Ponds & Water Features

Water Hyacinth

  • Give your garden pond an overhaul before the summer.
  • Everything that can grow, flower and live in the pond can go into it now. This includes water hyacinth, water lettuce and other tropical varieties. Ensure that 40-50% of the surface remains free of plants, partial coverage will help control algal growth through shading & uptake of nutrients.

Angela Slater

Daughter of a farmer and market gardener so have always had a connection with the outdoors, whether it was keeping animals or producing fruit, vegetables and cut flowers. Along with my work at Hayes Garden World I also have a smallholding, mainly breeding rare breed pigs. I gained an HND and BSc in Conservation and Environmental Land Management, as a result I am an ardent environmentalist and have a keen interest in environmentally friendly gardening. In my time at Hayes I worked for several years in the Outdoor Plant and Houseplant areas.