April is one of the busiest months; the days are lengthening, air and soil temperatures are rising. It is time to plant maincrop vegetables, and hardy annuals and perennials out of doors. Continue to sow for succession in the vegetable garden and manage your plants, which have germinated from last month’s sowing.
Bedding plants now appear on sale in the shops, but it is too early to plant out half-hardy annuals as there is still the likelihood of frosts which could destroy them. In the mildest areas, you can begin to harden off tender plants towards the end of the month.
The sowing of half-hardy annuals should be complete and by the middle of the month they will be ready to transplant into seed boxes. Hardy annuals can be sown directly into their flowering sites. Perennials that do not bloom in their first year can be sown in nursery beds.
In mild areas, plant out dahlia tubers at the end of the month; stock can be increased by root division. Cuttings taken last month can be gradually hardened off. Complete the planting out of sweet pea seedlings sown in pots.
This is your last chance to raise them by sowing directly into the ground. Continue to plant a succession of gladiolus corms until the middle of the month. Stake tall perennials as the shoots begin to develop. Lilies should be planted out of doors.
Once daffodils and other bulbs have finished flowering, pinch out the swollen round ovaries at the base of the flower but do not remove or cut back the leaves. Allow the bulbs to remain in the ground until the space is required for bedding plants next month.
During dry spells, all bulbs, including those which have finished flowering, should be watered as it is the time that next season’s bulbs are being created.
Apples should be sprayed with a general insecticide at the pink bud stage against apple blossom weevil and codling moth. Only spray where problems occurred the previous year– never treat as a matter of routine.
Clean strawberry beds, giving a top dressing of general fertiliser. Check for big bud on black currants, removing any infected tissue by hand. Tie raspberry, blackberry and tayberry canes into position.
During the day the windows should be opened to stop seedlings becoming leggy and to reduce the dangers of damping off. Close them at night and provide heat when there are frost warnings. Cuttings of geraniums and fuchsias for flowering later in the summer can be taken now. Sow seeds of cacti and succulents.
Pot on tomato plants in the cold greenhouse. During the middle of the month, runner beans may be sown for planting outside as well developed seedlings next month.
New lawns can be sown and repairs made during this month. Old lawns should be scarified to remove debris sown in pots and for aeration. Feed with a spring lawn fertiliser. If applying a lawn weed killer, do not cut the grass; instead, apply the weed killer and delay cutting for another week.
For the rest of the spring and summer, cut as necessary. Perennial weeds can be removed by digging out the crowns and roots with a penknife without using chemical treatment.
Pests and diseases
The abundance of young shoots and the intermittent wet weather results in slug and snails being particularly troublesome – control them with pellets. Birds, especially pigeons, are a serious problem this month. They are particularly attracted to pea seedlings. The only effective protection is wire mesh pea guards. Aphids will begin to emerge; spray with a systemic or contact insecticide or horticultural soft soap.
This month the pond continues to return to life as water temperatures begin to rise and fish take more food. Clean out the pond if it was not done during the autumn. Aquatics that have become overgrown should be lifted and divided. Plant in a plastic pond plant basket filled with good quality garden loam and weighed down with stones. Saturate the soil before lowering into the water.
Check that you have the correct depth of water for the variety of water lilies before purchasing. After obtaining the plants, wash them thoroughly to make sure you do not introduce any creatures to the pond that may prey on young fish. Keep a close lookout for fish eggs; if the pond is small there is a real danger that the larger fish may consume them or the fry, in which case the eggs should be transferred to an aquarium.
Perform any necessary pruning of shrubs such as forsythia that have just finished flowering so that the work is completed before the development of the following year’s buds. Prune members of the Prunus family, which tend to bleed less this month.
Removal of damaged branches of evergreens and pruning to restrict their size should also be completed in April.
Sow successions of salad crops –beetroot, lettuce, radishes and spring onions. Sow winter greens, kale and purple- and white-sprouting, broccoli; calabrese can be sown for cropping during the current summer.
Sow maincrop carrots and peas. Start thinning earlysown carrots and parsnips. In mild districts, plant an early row of dwarf beans during the last week of April. Indoors, sow marrows, cucumbers and pumpkins for planting out next month.
Plant early potatoes and complete the planting of onion sets. Weed seedlings will be beginning to emerge; the ground should be hoed when they are 2.5cm/1in high.