Garden jobs for April

General garden maintenance

  • Although it feels unlikely, beware of late frosts which could damage young plants — have some horticultural fleece ready to cover up.
  • Tidy up beds and borders. As a minimum, get rid of weeds which take moisture and nutrients needed by your plants. Dig out perennial weeds, and hoe away young annual weeds before they have a chance to get going.
  • Tie in climbing and rambling roses and other climbers with string, ties or wire that won’t damage the growing stems. With climbing roses, tie the long stems as horizontally as possible which will encourage the plant to produce flowers all along the stem.
  • Feed roses and other shrubs with proprietary or general fertiliser. If necessary, start treating against blackspot and mildew with an appropriate spray such as Roseclear.
  • If you haven’t done so already, apply a good layer of organic mulch such as well-rotted manure or organic compost. This will help to retain moisture around plants, and the nutrients will gradually be pulled down to the roots by worms and other bugs. You can also use a straw or bark chipping mulch which will help to deter slugs and snails. Before applying any form of mulch, ensure the area is weed free and that the soil isn’t dry.
  • Place plant supports over and around tall perennials before they need them, for the plants to grow through.
  • Deadhead daffodils and other spring bulbs when the flowers have gone over, but let the leaves die down naturally. This will replenish the bulb’s energy to form next year’s flowers. To help further, give the leaves a dousing of liquid fertiliser.

Container gardening

  • Top dress - Scrape the top layer of compost off containers and replace with fresh compost. If necessary, repot container plants, pruning roots and replanting in new compost.
  • Keep containers watered: wind and sun dry out compost quickly. Bigger containers retain water for longer so consider using a few larger pots rather than lots of little ones on your balcony or terrace.
  • Be imaginative. You can grow a wide range of plants in a container but it pays to be realistic. You will need to provide all the water and nutrients that the plants need and be prepared to re-pot them every few years. Why not try a pair of yew cones in matching pots, a beautiful alpine collection in a gritty well-drained compost, a shady corner container with ferns, heuchera and begonia, or a shorter-lived seasonal mixed container of euphorbia, viola and narcissi.

Pruning

  • Prune early flowering Forsythia and Chaenomeles once they have finished flowering. Forsythia should have flowered stems cut back to a strong new sideshoot and a few of the oldest stems removed from the base.
  • Prune late flowering deciduous shrubs such as Hydrangeas and Buddleia if you haven’t done so already — prune hard back to a leaf shoot or stem.
  • Clip evergreen shrubs and hedges of Photinia, Prunus lusitanica, Hebes, Fatsia, Choisya and Mahonia, always to a point of well-placed lower growth.
  • Camellias can be tidied up once the flowers have finished or if necessary to renovate.
  • Cut perennials such as Penstemons, Verbena bonariensis, Gaura and other summer flowerers to new shoots on last year’s growth.
  • Trim lavender, especially if you didn’t in the autumn, cutting out old flower shoots, and shorten new shoots by 2cm.
  • This is a good time to divide established bamboo, if necessary.

Planting

  • ’Right plant, right place’ is good gardening advice. In general, this refers to light levels, soil type and moisture levels. There are very few plants which will perform in permanent shade and some which tolerate dry soil and sun all day, but many more are happy in sun or part-shade. Always read the label on a plant to check whether it will be happy in the space you plan to plant it.
  • Plant a tree — there’s something suitable for every garden, balcony, and terrace.
  • Mediterranean type plants such as Hebe, Ceanothus, Cistus, olive and lavender can be planted as the soil begins to warm up.
  • Plant out autumn-sown sweet pea plants, or directly sow seeds outside.
  • *Plant your new plants well — have a look at our Planting guide.

Growing from seed

  • April is normally the month to begin seed sowing outside, but only once the temperatures have begun to rise. Carrots, beetroot, peas, broad beans, lettuce and spinach can all be sown directly into prepared drills. Always read the instructions on the seed packet.
  • With tender vegetables, the smaller the seed, the earlier it needs to be sown, so start off aubergines, chilli peppers and tomatoes as soon as you can — in seed trays in a greenhouse or on a windowsill.
  • Towards the end of the month and into May, larger seeds such as sweet corn, courgettes, squash, pumpkins and runner beans can be sown directly outside.
  • All tender vegetable seedlings should be hardened off before planting out and not put outside until the risk of frost has passed. A cold frame is invaluable for hardening off, if you have space.
  • Direct sow sunflowers, poppies, pot marigolds and other annual flowers.
  • Seeds will germinate more easily in a warm soil so it may be worth warming the soil before sowing or planting, with cloches, sheets of plastic or old carpet.

Fruit & Vegetables

  • Whatever size your vegetable plot is, it pays to plan. Use techniques of crop rotation (moving crops you grow each year from one area to another), successional growing (growing quick cropping plants such as lettuce or pea shoots at regular intervals) and intercropping (for example growing quick radishes or lettuce in between rows of sweetcorn or potatoes before they grow and block the light)
  • Sow quick maturing leaf crops at two week intervals to have a steady supply of cut and come again salad. Try lettuce, chard, beetroot, spinach, and any other favourites. Rows of seeds can be a centimetre apart, in a seed bed or in a grow bag or container.
  • When tomato seedlings have their first pair of true leaves, pot on into individual pots. Grow on in a bright spot and plant into their final growing positions once the first flowers turn yellow.
  • Thin carrot seedlings in the evening when there are fewer carrot flies around.
  • *Feed soft fruit bushes and strawberries with a general fertilizer to encourage bumper crops.
  • Fruit bushes and trees can be planted, but pinch out flowers and small developing fruit in the first year so that the plant’s energy goes into building a strong root system.
  • Protect young brassicas and carrots from pests by covering crops with horticultural fleece.

Herbs

  • Sow and plant new herbs to have a continued supply through the year ahead. Rocket, basil, coriander and dill and others can be sown at 2/3 week intervals.
  • If mint has been in the same container for more than a couple of years, empty it out, cut it into quarters and replant two quarters back-to-back in fresh soil/compost.

Lawns

  • Work on the lawn now, to get it ready for the summer months. Spike compacted areas with an aerator, or a garden fork, and apply a fertiliser or top dressing.
  • Mow the lawn, if needed, on dry days with the blades set high for the first few cuts.
  • Repair bumps and hollows in lawns by peeling back turf and adding or removing soil.
  • Spring lawn feed products contain moss killer, weed killer and fertiliser — follow the pack instructions for rate of application. It can be useful to divide the lawn and the fertiliser into two or four to make sure you don’t use too much in the first section.
  • After applying moss killer, rake out blackened moss and thatch two weeks later. Don’t worry — it will look worse before it gets better!
  • Sow lawn seed on bare patches, and water during dry spells.

Houseplants

  • Start feeding house plants as they start putting on new growth.

Pests and diseases

  • Check emerging growth in the garden and guard against slugs which will happily feast on young and tender leaves and shoots.
  • Watch out for early insect attacks. Small infestations of aphids can be squashed by hand if you aren’t too squeamish. Watch out too for lily beetle, vine weevils and other infestations; remove and dispose of any you see, and treat with an appropriate insecticide.
  • If using an insecticide, use it wisely to avoid killing beneficial insects. Don’t use sprays if there is even a whisper of a breeze, because the insecticide will be carried. Ideally spray early morning or late evening when fewer flying insects are around.
  • Look out for blackspot on rose leaves and pick off affected leaves — early removal and control may eliminate the need for fungicide treatment.
  • Slugs dislike strong smelling plants, so try planting a selection of mint, chives, garlic, geraniums, foxgloves, lavender and fennel around the edge of your garden to deter them.

Wildlife

  • Keep bird feeders topped up. Position feeders where you can see them from the house, and ideally out of reach of cats.
  • Water is important for birds and other wildlife in the garden, so provide a saucer or bird bath which you top up daily, or think about a small pond.
  • Ensure birds are not nesting before pruning evergreen shrubs and hedges.
  • Sow or plant a wildflower area to encourage beneficial insects to the garden.
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