Plants should be putting on lots of new growth now, so if you have any perennials to lift and divide, or new ones to plant, do so as early in April as possible to allow them the maximum time to settle in. Start feeding established perennials now with a general fertiliser.
Continue to take cuttings of fuchsias, geraniums, dahlias and chrysanthemums during April, for a late summer flowering display.
As the weather improves in late April, begin hardening off those cuttings that were taken last month and have formed roots. Use a cold frame or find a sunny, sheltered spot outdoors. Leave the plants there during the day, but bring them in at night, when temperatures drop.
Pinch out the growing point when rooted cuttings are about 15cm (6 in) high. This encourages the young plant to produce side shoots, which in turn will produce more flowers, rather than expending all its energy in producing a single, tall stem.
Hardy annuals are the main flowers to be sown in April. Choose a windless day as fine seeds can easily be blown all over the place. Most hardy annuals can be sown where they are to flower. Ideally they can be used to fill up gaps in developing shrub borders or to add colour to mixed borders. If space permits, you can also sow them in drifts and groups of different flowers. If you are planning a large annual border, it should first be marked out, and then the seeds sown in lines or broadcast in a pre-arranged location for each variety.
Seeds of herbaceous perennial plants may also be sown in April, either direct into the ground or into pots or trays, instead of sowing the seeds in their final positions. Sow thinly and plant the resulting seedlings in nursery rows about 30 cm (1 ft) apart when they are about 10 cm (4 in) tall. Plant them out in their final positions in the late summer or autumn. If you have a frame to sow in, this will give you larger plants more quickly, and many perennial sown under cover often flower in the same year.
Half hardy annuals can also be sown in April, but only under a frame or cloche because they can easily be killed by the lightest of frosts. Once they have germinated, give them all the ventilation you can, provided that the outside temperature is reasonably warm.
Violas and pansies can be planted out now, either ones bought from a garden centre or your own seedlings or rooted cuttings. Light shade is much appreciated, and watering at the first sign of dry weather.
Antirrhinums, sown in January or February or propagated from cuttings last autumn, can also be planted out in April, provided they have been hardened off first. Ensure that all sign of severe frost is over before planting as it would be a shame to lose these carefully nurtured plants.
Plant-out sweet peas as early as possible to ensure a good show of flowers. Sweet peas root deeply and need plenty of nourishment, so plant them in rich soil in a sunny, sheltered position.
Don't forget to provide canes or pea sticks for the taller growing varieties. However, if you prefer the rambling, natural growth, which means smaller but quite plentiful flowers, simply let them climb freely on bushy pea sticks.
When space is short in outdoor beds you can grow sweet peas in a tub, trained on a wigwam of canes placed in a circle and tied at the top.
Check container grown plants to see if they are pot bound and need potting on into larger containers. Those that have reached their full size may need re-potting into fresh compost. For potting on, choose a pot with a diameter of at least 2.5cm (1 in) larger than the previous.
Don't forget to add suitable material in base for drainage. Ideally, place broken bits of flower pot, convex-side up, over the drainage hole. Cover the crocks with a layer of good-quality, loam or compost.
Carefully knock the plant to be re potted out of its old pot, and remove any crocks that may be caught in the tangle of growing roots. Place it centrally in the new pot, then add compost round the sides until the pot is full. Tap the pot once or twice to allow the compost to settle, firm lightly then top up again, leaving room for watering.
Water with tepid water and place the pot in a lightly shaded spot for a few days to allow it to acclimatise.
Once daffodil and other narcissus flowers have begun to wither, pick off the dead heads. This prevents the heads producing seeds and weakening the bulbs. Do not remove any of the foliage or stem, while it is still green and healthy. Leave it on until it has started to turn yellow. The leaves feed the bulb and builds up its energy reserve for next year. Apply a general fertiliser around the bulbs.
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Herbaceous perennials in flower this month:
In addition, many alpine and rock garden plants flower in April.
Bellis perennis (daisy)
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