Jobs to do in the garden this week.

  • Cut runners from strawberries (unless trying to propagate more plants). Runners will divert energy away from crop production.
  • Remove spring bedding plants and lift and store spring flowering bulbs (with the exception of snowdrops).
  • Prune helichrysum and artemisias shrubs to encourage bushy plants.
  • Clean the leaves of smooth leaved house plants. Wipe large leaves such as those found on rubber plants, swiss cheese plants and umberella plants, with a damp cloth. Smaller leaved plants can be dipped in a bowl of clean water. Do not attempt to wash the leaves of 'hairy' leaved plants such as African violets, use a soft brush such as a paint brush or a used toothbrush.
  • Support herbaceous border plants with canes, where they will be needed in late summer. It's easier to do this now while the plants are still small, this also reduces the risk of damaging the roots later in the season.
  • Prune plum trees, paint fresh cuts with Arborex to prevent infection.
  • May is an ideal time to create ponds / pools. Click here to see the pond project page.
  • Spray roses with 'Rose Clear' to kill aphids and protect from blackspot.
  • Trim hedges to encourage the branches to thicken up and to keep them neat and tidy.
  • Take soft wood cuttings from thyme. Thyme cuttings take easily, so they can be stuck in the soil or in pots. Remember that thyme likes full sun and hates to be grown in the shade.
  • Plant out greenhouse grown runner beans or sow them at the base of wigwams 5cm (2in) deep. Keep well watered.
  • Fuchias flower from the ends of their branches, nipping out the growing tip will encourage more shoots, creating a bushier plant with more flowers.
  • Replant dahlia tubers that have been lifted and stored for the winter. Put a stake in now to save damaging the plant and roots once it has started growing.
  • Propagate marginal pond plants. Take short cuttings, remove lower leaves and push stems into pots of mud. Keep top of the pots just under the surface of the water.
  • Lots of tender plants can be grown outside in containers between May and September as long as the pot is big enough and they get enough water and the occasional feed.
  • If becoming boisterous, prune spring-flowering clematis including alpina and macropetala after flowering. Use cuttings to propagate new plants.
  • The adult vine weevil, the number one garden pest, will be emerging from the soil as the temperatures rise.
  • Control weeds in lawns with a selective weedkiller. Don't cut the grass for at least a week after applying. Don't put these grass cuttings on the compost heap.
  • Protect plants from slugs and snails with slug pellets, course grit or traps. Alternatively try to encourage birds, hedgehogs and frogs to your garden - all prey on slugs and snails. More suggestions to reduce slug and snail damage.
  • Regularly water trees and shrubs that were planted last autumn and winter. Their roots won't have had a chance to fully develop yet.
  • Thin out seedlings, leaving the strongest growing plants. Water the soil gently beforehand to reduce soil disturbance.
  • Cut grass weekly, long grass takes more nutrients out of the soil. It is also harder to cut and may leave yellow patches in the lawn.
  • Apply a weed and feed to established lawns. Water in with a hose after a few days if it hasn't rained.
  • Open cloches ends to allow pollinating insects access to flowering plants. Remove cloches in late spring.
  • Plant up new ponds with aquatics, including oxygenators.
  • As daffodils fade, remove the flower heads. Don't cut back the leaves - leave them to die back naturally. However if you want to tidy them up, wait until the leaves have yellowed before removing.
  • Feed established roses, fortnightly, with a rose fertilizer, dead-head regularly and check for aphids and black spot.
  • Plant maincrop potatoes in prepared ground or potato growbags.
  • Now is the best time to plant lavender. Widely grown for its scent and foliage, lavender is ideal for borders or a low hedge. Available in shades of purple, blue, white and pink it is a magnet for bees and butterflies
  • Lift, divide and replant chives.
  • Remove the dead heads of spring flowering bulbs, such as tulips and daffodils, before they have a chance to produce seed. This will encourage the plant to store energy in the bulb rather than wasting it on seed production.
  • Postion plant supports where they will be needed in late summer. Doing this now reduces the risk of damaging the roots later in the season.
  • If your lawn is more moss than grass, then treat with a lawn moss killer. Bare in mind that the moss will turn black within a couple of days, so don't be too alarmed. A couple of weeks after application, if you are left with bare patches in your lawn, mix equal quantities of grass seed and seived compost and scatter over the patches, cover areas with fine netting or twigs gently pushed into the soil, to protect from birds and animals. Combination lawn feed and moss killer is available, but feeding your lawn when it's not necessary will encourage it to grow quicker and therefore need to be cut more regularly.
  • Sow vegetable seeds (courgette, marrow, runner and French beans) in the vegetable patch and salad seeds (lettuce, spring onion and radish) little and often to provide a staggered harvest through the summer.
  • Prune lavatera hard, down to healthy young growth.
  • Don't be tempted to buy your summer bedding yet, unless you have a greenhouse, conservatory or cold frame that you can store them in. A late April / early May frost is not uncommon in the UK.
  • As summer-flowering herbaceous perennials start to come back to life, lift and divide overgrown plants.
  • Scatter growmore granules under fruit trees and bushes, especially apple, pear and plum trees. If it doesn't rain for a couple of days, water the granules in with a hose or watering can. Growmore is a slow release, general fertiliser, it includes the three main plant nutrients (nitrogen, phosphates and potassium).
  • Begin regular cutting of your lawn. If the grass is long increase the height adjustment of the mower to the highest setting. Once this first cut has been done, lower the blades/deck and go back over the lawn.
  • Your pond may have started to turn green and cloudy. This is due to a rapid increase in algae, which flourish in the warmer spring temperatures. Once the pond plants start to grow again, especially the oxygenating plants, these will use up the nutrients and create shade, reducing the amount of algae. To speed up the clearing of the water, drop a small string bag/pair of old tights stuffed with barley straw, into the pond. Weigh the straw down, so that it floats just below the surface of the water.

    As the straw breaks down, it produces hydrogen peroxide, which reduces and inhibits the growth of algae and blanket weed. If the algae is particularly bad, barley straw extract can be bought in liquid form and added to the pond water (follow the instructions on the bottle, but as a guide before purchasing,125ml treats approximately 4,500 litres/1,000 gallons, but multiple, fortnightly treatments through the year may be necessary). If you have a fountain or waterfall, try to position the barley straw underneath this. Remove and replace the barley with new straw after about six months, before it completely rots down, polluting the water.

    The small, pre-filled barley straw bags to add to your pond, cost about £2 each, but you can buy a 17 litre pack, which will last a few years for about £10 from your local pet shop or Amazon here: Supreme Petfoods Tiny Friends Farm Russell & Gerty Barley Straw, 17 Litres

  • Weed and spread compost from the compost bin over the borders and vegetable patch. This adds valuable nutrients to the soil and acts as a mulch, to retain moisture and reduce weed growth. Ensure that the soil is moist before adding mulch.
  • Transplant any self-set aquilegia, lupins and hollyhocks to new locations.
  • As it's starting to warm up, it's a good time to lay a new lawn, although the best time is in Autumn or late winter, as it's damper and cooler, allowing the turf to bed in without you having to worry too much about regular watering. See here: laying a new lawn for further information.
  • Remove algae and moss from patios and paths with a pressure washer or proprietary patio and path cleaner (traditionally a tar oil winter wash could have been used, but these are no longer available, particualrly to the amateur gardener, as they were found to be carcinogenic).
  • Keep an eye on the weather forecast. Cover shrubs that are likely to be damaged by frost with garden fleece, sacking or an old light blanket.