Gardening jobs this month: April

From Country Living gardening editor Stephanie Donaldson:

● Check for emerging self-seeded plants and transplant or pot up before weeding and mulching borders.
● Place saucers under container plants to conserve moisture.
● Dead-heading naturalised bulbs will keep them vigorous and healthy.
● Prick out and pot on seedlings before they become overcrowded,
● Remove side shoots and pinch out tendrils on cordon sweet peas.
● Divide sprouted dahlia tubers; pot up individual tubers with strong shoots
● Repot container plants that are pot bound, gently loosening rootballs before moving to larger containers.
● Lift and divide overgrown waterlilies, replanting divided plants in aquatic compost topped with washed gravel in a planting basket.
● Once the soil has warmed up, weed borders and apply a moisture-retaining mulch.
● Use fleece to protect young growth from frost.
● Stake tall-growing perennials.
● Shorten the straggly shoots on camellias after flowering.
● Rake moss from the lawn with a spring-time rake towards the end of the month.
● Divide pot-grown agapanthus. Though they do like to be crowded, this is necessary from time to time. Remove from pot and use a spade to chop into two or four pieces and plant in fresh compost.

Pests and diseases
● Put brassica collars around cabbages and cauliflowers to deter cabbage root fly and erect low screens around carrots to keep carrot fly at bay.
● The first lily beetles will be appearing around now in affected areas. Pick off the bright red beetles and squash them.
● Start slug and snail patrol.
● Apply a first dose of anti-slug nematodes (available from www.greengardener.co.uk) once soil warms up sufficiently 

In the greenhouse
● Ventilate greenhouses in good weather to prevent a build-up of pests and diseases.
● Move young plants from greenhouse to cold frame.
● Feed, water and ventilate plants in greenhouses and cold frames.
● Introduce biological controls in the greenhouse.  

Fruit and veg
● Sow a small row of salads every two weeks.
● Sow carrots and parsnips outdoors for autumn cropping but remember to protect both from carrot fly.
● Sow main-crop peas, winter brassicas and beetroot.
● Pot on outdoor tomato plants and plant tomatoes in the greenhouse border.
● Use a spade to cut away the offshoots from globe artichokes and plant them in well-manured ground.
● Prune plum trees.
● Check for emerging self-seeded plants and transplant or pot up before weeding and mulching borders.
● Cut back sage growth by half to keep it shapely. If it has become leggy, prune hard to within 15cm of the ground. 
● Prepare runner-bean beds.
● Remove flower buds on rhubarb plants.

Sarah Raven's tips from Good Housekeeping

● Dig flower beds to prepare the soil
● Mulch flower beds with a 4-5cm layer of compost to suppress weeds
● Lift and divide snowdrops
● Plant tubers and seedlings, such as dahlias and sweet peas
● Sow easy seeds now and you'll reap rich rewards later in the year. Get going with quick-growing flowering plants such as the endlessly gorgeous cosmos family. These prolific bloomers excel in my garden every year. My favourites are:
❀ Pure white ‘Purity'
❀ Pink and carmine centred ‘Versailles Tetra'
❀ Pure carmine ‘Dazzler'
I also recommend adding one or two sunflowers:
❀ Deep wine red Helianthus ‘Chianti'
❀ Creamy-yellow H. debilis ‘Vanilla Ice' 

From House Beautiful's Denise Brock

Dig over the soil Take care not to damage existing plants, and if there are areas that you can turn over to a fork's depth, do so, as this aerates the soil. Remove weeds at the same time.
Improve the soil Add plenty of compost, and, for heavy clay soil, add grit, too. Special products such as J Arthur Bower's Extra Care Soil Improver, £5.49 for 60 litres, help with heavy clay soils. Sprinkle on a general fertiliser to encourage plants to grow in the coming months.
Dig up and divide
Divide plants that grew too big for their space last summer into smaller pieces. Water the soil if dry, loosen with a fork and dig up as much of the root as possible. Use two forks back to back to divide the root. Discard old sections and replant half or less with a little compost and fertiliser.
Spread mulch Help beds retain moisture and suppress weeds by spreading leaf mould or compost. Work finer materials 5cm into the surface of the soil, but when you come close to plants, leave it on top of the soil so as not to damage the roots. Soil improver is often better value than bagged compost.
Spread bark or chips A depth of 5cm for bark is best. Over time it will gradually work its way down into the soil itself.
Fix supports early Plants emerging from the soil are a reminder that they'll probably need support in a few weeks. Put them in now so that the plants grow through them. Plastic coated rings and legs cost from £13.95 for a set of two, Harrod Horticultural.

From Prima gardening expert Ann-Marie Powell:

● Lift and divide perennials before new shoots develop.
● Prune buddleja bushes to about 30cm to 50cm from the ground.
● Plant out early and maincrop potatoes.
● Pinch out the tips on sweet peas.
● Sow veg like courgette, marrows, tomato and sweetcorn indoors.
● Put out supports for herbaceous perennials.
● Plant trees, shrubs and climbers before the weather warms up.
>● Deadhead daffodils as soon as the flowers fade, so they don't waste their energy producing seeds.
● Start trimming your box hedges and topiaries now, or wait another three to four weeks in colder areas.
● Thin out old clumps of bamboo to allow this year's shoots lots of space.
● Sow runner, broad and French beans, beetroots, carrots, cabbages, salad onions, spinach, herbs and Brussels sprouts outside.
●  Sow hardy annuals, such as calendula and nasturtium, in shallow drills or patches.
● For summer evening fragrance, sow night-scented stocks (Matthiola longipetala and M. bicornis).
● Repot over-wintered geraniums, pelargoniums and fuchsias into fresh compost and feed them every three weeks. Place outside when danger of frost has passed.
● Now's your last chance to plant your summer-flowering bulbs and rhizomes. These include hedychium, gladioli, nerines, eucomis and dahlias, lilies and gladioli.
● Give shrubs and roses a feed of slow-release fertiliser (fish, blood and bone).
● Start giving houseplants more water.
● Feed citrus plants with a high-nitrogen feed.
● Sow new lawns, repair bald patches and damaged edges.
● Give your lawn its first cut.
● Continue to deadhead spring-flowering bulbs such as daffodils and apply a general feed.
● Replenish the top couple of inches of compost and mulch on container plants, and give them a good liquid feed.
● Sow salad, broad beans and peas directly into the soil. Read more on growing salad crops
● Sow herb seeds in the greenhouse or on the windowsill. Read more on growing herbs
● Keep on top of weeds.