April in the garden
April is the busiest time in the garden, but don’t panic, take things one step at a time and you’ll get it all done. It’s important to take a few moments to sit in the sun, listen to the birds and admire any colour you have in the garden. Make a note of any gaps in your spring planting to order any bulbs in the autumn for next year.
the cutting garden
sowing & growing
- Start to direct sow hardy annuals, eg marigolds, poppies, dill, cerinthe, nigella, etc.
- Harden off seedlings that have been started off indoors on warm still days. Place them outside during the day, but take them in again late afternoon, and do this for about a week or so. This way they will get used to the cooler conditions before being planted outside. Start planting out half-hardies, eg cosmos, in sheltered spots at end of the month.
- Prick out cut flower seedlings. Good examples are Bells of Ireland (Moluccella laevis), amaranthus, tithonia and cleomes. Remember to get as much root as you can by pushing your dibber (or use a rigid plant label) right down to the base of the seed tray and lifting from there.
- Sow perennials – these could include hollyhocks, delphiniums, Linaria purpurea 'Canon Went' and echinaceas. Fill a seed tray with peat-free compost and dampen with water. Sow seeds spaced at least an inch apart in a grid across the compost surface. Then scatter (or sieve) a fine covering of compost over the seeds. You don't need to water again immediately. Place in a light, cool spot, eg a window ledge or, if you have one, in a propagator in a cold frame, greenhouse or polytunnel with basal heat.
- Later in the month, thin out hardy annuals sown in drifts or rows to allow plants to reach optimum size.
- Pot cuttings of tender perennials, eg pelargoniums, arctotis, verbenas, penstemons and argyranthemums, taken late last summer or autumn. They'll be well rooted now and will benefit from some fresh compost and more space for root formation before planting in their summer position.
- Plant out sweet peas – two plants to each upright. Dig a good, deep hole and fill the base with farmyard manure. Tie them in to the base of the arch or frame and water them in well.
- Create new plants from last year’s pelargoniums – take cuttings now and they’ll be ready to be replanted in a couple of months and be in full flower in four (don't miss Sarah's How to take pelargonium cuttings video for a quick guide).
bulbs & tubers
- If you have received your dahlia tubers, now is the time to get them potted up. Follow our instructions carefully and you will have wonderful flowers to cut all through the summer months.
- Finish planting summer-flowering bulbs. This includes eucomis, crinums and the deliciously scented cousin of the gladiolus – acidanthera. Plant them in pots or in the ground.
- Plant lily bulbs straight into the ground. Give them plenty of room and, on heavy soil, add grit for drainage to their planting hole. Most varieties thrive with their bulbs in some shade and tops emerging into full sun.
- Any indoor forced bulbs – hyacinths or Narcissi 'Avalanche' and 'Cragford' – can be planted into the garden when they've finished flowering. (NB paperwhites are not hardy, but don't chuck – keep the bulbs for planting again next autumn inside). I plant all my forced hyacinths together in a partially-shaded bed so they don't create a dotty effect all round the garden for years to come.
Lovely things to pick and arrange from your garden in April:
perennials, shrubs & trees
pruning & tidying
- Keep on top of the tiny annual weeds emerging with a hoe. Only hoe on dry days – this way any weeds that you hoe will die off and wilt quickly. Run the blade back and forth over the soil to break it up and cut down any of the newly sprouting weeds. You can save so much back-breaking work later on if you do this every other day for a few minutes.
- Perennials such as bindweed will start to appear big-time now. Dig them out, tracing the roots as far as you can, or train the tip up a bamboo cane and then treat with a suitable weedkiller.
- Cut back the last of the perennials and lightly fork over the soil carefully without damaging emerging shoots.
- To keep your roses growing healthily and for the best flowers this summer, make sure that your climbing roses are well tied down. Bend over any upright stems to encourage more flowers – you will normally only get flowers at the top of an upright, but if you bend them you will get more flowers along the stem. Tie them in so they are lying horizontally. This will also create a thicker screen, if you are using the rose as cover or to beautify a not-so-pretty wall or fence.
- Lavender plants need cutting back now to prevent them from looking sparse. Give the plant a short back and sides with secateurs to snip off old flower stems and shoot tips. Don't prune hard into old wood, as this will prevent new growth. While you are pruning, shape the plants into domes and remove any leggy or unwanted stems. Give the plants a weekly liquid feed during the summer, to encourage growth.
- Tidy up tussock-forming grasses with a shaping haircut.
- Now is also the time to divide and replant species such as Stipa gigantea, which struggle when newly planted in the wet and cold of winter.
- Last chance to cut back shrubs, especially those grown for colourful winter stems (eg dogwood or willow). Cut back to buds about knee height, then feed and mulch. Also cut back winter flowering jasmine when flowering has finished. Prune back to within 5cm of the old wood to promote branching.
- The late summer flowering Viticella-type clematis need pruning now. Cut them back to about knee height, above a clutch of growth buds. Spread the stems as much as you can on their support or frame for greater impact. Feed and mulch with a general-purpose organic fertiliser.
- Plant new evergreen trees and shrubs.
- With the soil warming up, it is also a good time to move evergreen trees or shrubs. Their roots will then grow off fast, but you must keep them well watered until autumn.
the kitchen garden
- Try direct sowing some new salad leaves, carrots, peas, beetroot, spinach and chard.
- Sow some quick growing half-hardy annuals, like pumpkins, squash, sweetcorn, basil and French beans.
- Plant Maincrop potatoes.
- Plant tomatoes and cucumbers (under cover).
- Keep on top of thinning seedlings.
- Rotavate the vegetable garden. Get ready for a mass sowing of hardy annual veg, such as spinach, carrots, beetroot, lettuce and radish. On heavy soil, integrate plenty of grit and organic matter. On freely drained soil, only muck and/or compost need to go in.
- Plant out onions, shallots and garlic.
- Pot on tomatoes. It’s tempting to move tomatoes from a module or seed tray straight into their final, large planting pot, but this slows growth. Tomatoes like to feel contained and cosy; their roots can’t cope with a large volume of compost and tend to rot. Pot them only one size up and add a cane at their side to support them as they grow.
- Plant asparagus crowns.
salad & herbs
- If you want to get going with some salad, sow now undercover or in gutters in your greenhouse or conservatory. Eg corn salad, rainbow chard, mizuna, rocket, winter purslane, mustard and plenty of lettuces.
- Direct sow chervil, chives and coriander or sow dill, fennel and French sorrel under cover.
- To avoid risk of infection, stone fruits such as plum, cherry, peach, nectarine and apricot should only be pruned during the growing season. Prune late April, when the plants are in leaf and after flowering. Immediately seal all cuts greater than 1cm (½in) with wound seal.
- Repot your citrus in fresh citrus-specific compost. If you can’t find this, ericaceous is the next best thing.
- Top dress blueberries grown in pots with ericaceous compost. It’s important to have two different varieties of blueberries to get good production – they will fruit without, but you’ll get a paltry quantity.
- All soft fruits, eg strawberries, raspberries, redcurrants, blackcurrants, and gooseberries, will benefit from a mulch. Garden compost, leaf mould, organic manure, straw, hay and spent mushroom compost can all be used.
Here's what you could be picking and eating this time next year or, if you’re an old hand, already are:
- Brassicas: red & green cabbages, kale, forced sea kale, cauliflower and Cima di Rapa, purple and white sprouting broccoli, spring cabbages
- Roots: Jerusalem artichokes, parsnips, first radishes
- Salad crops: salad leaves, over-wintered lettuce, pea tips
- Leafy greens: chard, perpetual spinach and true spinach
- Start staking delphiniums and tall perennials. They'll soon be tall enough to be knocked over by wind or heavy rain. If you can get your hands on some hazel or silver birch pea sticks, use them to weave a basket, which works just as well but looks so much nicer than metal or plastic.
- Plant up hanging baskets and containers. Keep them under cover to grow on until the frosts have passed. Go for something exceptionally long-flowering such as Argyranthemum 'Cherry Red' or Verbena 'Homestead Purple'.
- Keep an eye on permanent or spring plantings in containers and water if necessary.
- With the dryer weather, do the first cut of your lawn, making sure the blades are set quite high. You can smarten everything up by cutting your lawn edges too.
- Continue to sow or lay new lawns. Ensure that they do not dry out during dry spells.
- Feed lawns and treat for moss. Try to work out the reason for the moss. Is the grass too shady, or the soil too acid or compacted? Aim to sort the problem out now for a lovely lawn all summer.
in the greenhouse
- If you have a greenhouse, sow large seeded, large-leaved vegetables, eg cucumbers and courgettes. You'll then have an early July harvest.
- If necessary, ventilate glasshouses on warm days.
- If you have any spare space in a greenhouse around potential tomato beds, direct sow a pack of zinnias. They’ll give you vases of flowers to pick right the way through the summer.
wildlife & pests
- Snails and slugs love the warmer and wet weather, and before you know it you'll be overrun. Use Nemaslug (biological slug control) on your slugs and this should really help.
- Hedgehogs, frogs, toads and thrushes prey on these pests, so make sure you encourage these creatures in the garden. If you lay a flat stone on the ground, you will soon be able to see whether the thrushes have been using it as a place to smash snail shells. Put out additional food (eg tinned dog food) for hedgehogs.
- We've spotted the first lily beetle already in the garden at Perch Hill, so get your squishing fingers out. Or use Py Spray.
- Don't forget to leave water dishes and bird baths for the bees and the birds. They all need lots of water.
- Sow a wild flower meadow to encourage pollinators.