What to do during April in your garden and greenhouse?

Spring is well and truly here. What do we need to do in the garden throughout April?

Garden maintenance

• Put a bag of barley straw in ponds to discourage algae and keep the water clear all summer

• Lay turf or sow grass seed to create a new lawn or repair damaged patches

• Cut back tatty old fern fronds to make way for new ones that are starting to unfurl

• Keep cloches or large sheets of fleece handy to protect young plants if late frost is forecast

• Cut away unwanted suckers growing around the base of trees and shrubs

• Hoe between rows of veg seedlings regularly, as weeds grow rapidly at this time of year

• Remove moss and weeds in turf, and boost growth with a nitrogen-rich lawn feed

• Check that guttering on sheds and greenhouses is clear of debris, so that April showers will fill up water butts

• Add new aquatic plants to ponds and divide established plants that have outgrown their baskets

• Put pumps and fountains back into ponds, thoroughly cleaning the filters first

• Treat problem weeds, such as nettles and brambles

• Look out for clusters of aphids on shoot tips and young leaves, and wipe off before they multiply

• Keep putting out food for birds, as they're busy raising their broods

Greenhouse

• Prick out seedlings growing in pots and trays as soon as they produce their first true leaves

• Sow sweet peas in deep pots and keep them frost-free in a greenhouse or on a sunny windowsill

• Start feeding houseplants once a week with liquid fertiliser, continuing through to autumn

• Sow quick-growing microgreens, such as kale and mustard, for nutrient-rich pickings in just a few weeks

• Transplant greenhouse tomatoes into growing bags or large containers and tie in the stems to supports

• Plant up hanging baskets and pots with summer bedding, but keep indoors until after the last frost

• Sow herbs in pots or trays, including basil, chives, parsley, fennel and coriander

• Thin out heavy fruit sets on peaches and nectarines, leaving fruits about 10cm apart

• Sow runner beans, French beans, cucumbers, courgettes, pumpkins and sweetcorn in pots

• Pinch out the shoot tips of fuchsias to develop bushier plants

• Attach guttering to the greenhouse and install a water butt, so you can make good use of April showers

• Clean greenhouse glazing to let in as much light as possible

• Maintain good plant hygiene, picking off faded blooms and dead leaves before fungal diseases can take hold

• Open greenhouse doors and vents on warm days, or install automatic vent openers, to improve air circulation

Fruit and veg

• Plant second-early and maincrop potatoes

• Place cardboard collars around the stems of brassicas to deter cabbage root fly from laying their eggs

• Pinch out the tips of broad beans if they're covered in aphids, or spray shoots with soap-based solution

• Sow outdoor varieties of tomatoes, chillies and courgettes in pots, so they're ready to plant out in late May or June

• Divide clumps of hardy herbs, such as lemon balm and chives, then replant in pots, borders or a dedicated herb bed

• Sow small batches of rocket and other easy salad leaves

• Continue planting bare-root asparagus crowns and Jerusalem artichoke tubers

• Sow flowering companions in the veg plot, such as pot marigolds and borage

• Continue planting batches of garlic, shallots and onions every few weeks to extend the cropping period

• Sow herbs such as parsley, coriander, dill and chamomile in a sunny bed or container

• Protect emerging seedlings from slugs and snails

• Sow fast-growing crops, such as radishes, to make the most of any temporary gaps

Flowers

· Sow hardy annuals, such as love-in-a-mist and pot marigolds, as well as native wildflowers, into gaps in borders

· Enjoy instant colour by planting primulas and polyanthus in pots and at the front of borders

· Protect the new shoots of hostas, delphiniums, lupins and other vulnerable plants from slugs and snails

· Continue deadheading spring bulbs and bedding, so they don't waste energy setting seed

· Plant pineapple lily (eucomis) bulbs in pots for exotic-looking summer flowers

· Sow sweet peas at the base of supports, and transplant those sown in autumn into their final positions

· Spray the new leaves of disease-prone roses with fungicide to control mildew, rust and blackspot

· Take basal cuttings from clumps of perennials, such as delphiniums, campanulas and lupins

· Prune hydrangeas, cutting back the old stems to a healthy shoot lower down

· Reinvigorate mature clumps of hardy perennials, such as hostas, asters and daylilies, by dividing and replanting

· Sow sunflowers in a sunny, open site, then water regularly and protect seedlings from slugs and snails

· Check for aphids on roses and rub them off before they develop into major infestations

· Add aquatic plants, such as waterlilies and irises, to garden ponds