The warmth and wet of the last two months will, one hopes, have brought outdoor plants on fast, and flowering will really get under way. Border plants will shoot up and may need staking, particularly peonies. Annuals sown out of doors should be thinned. Dahlia cuttings or tubers which have sprouted can be planted out at the end of the month, when frost is unlikely, also tuberous and fibrous begonias which have started into growth, with the same reservation. Gladiolus corms can be planted in sandy soil and a sunny place. Chrysanthemums may be set out, in pots, or in the soil directly, from mid May onwards, and freesias grown from seed can be placed in a shady position in late May.
The April-flowering shrubs can be pruned, especially clematis, and those flowering in early May; included will be forsythia, kerria, Spfraea argut a, S. thunbergn and berberis. Rhododendrons, azaleas and lilacs should be deadheaded as soon as the blooms have finished. Evergreens and tender shrubs can still be planted; hibiscus is likely to remain apparently lifeless after planting, until July. Planting of water plants can start now that the water is beginning to warm up.
Grass cutting should continue at five-day intervals, and a combined feed and weed application will do much good if applied now, when weeds are at their highest rate of growth. Lawns sown from seed last month will need topping this month.
Mulching can still be done if missed last month. Biennials are sown this month for flowering next spring, e.g. wallflowers, Sweet Williams, Canterbury bells (Campanula medium) -the pink ones are unusual and pretty, and antirrhinums. Foxgloves, verbascums, pansies and polyanthus are also treated in this way.
This year’s spring bedding will need clearing away, and spring-flowering bulbs can be lifted to make way for summer bedding. They are heeled in, that is, laid at an angle in a shallow trench, with the leaves exposed, but the bulbs covered with soil, to finish ripening, so that the embryo flower can form, ready for the next season. Sweet pea supporting and training, if grown as cordons, should start.
The compost heap will be growing daily; it is an essential to good gardening, and can consist of any green vegetative material, grass cuttings, weeds, soft shrub prunings, leaves and flower stems. Weeds should be pulled before they flower, otherwise the heap is likely to be full of weed seeds unkilled because of insufficient heat within the heap. A 6-in, layer of vegetation can be sprinkled with sulphate of ammonia, and the next layer dusted with lime. The heap can be built in this way with lime and ammonium sulphate alternating, or Nitro-Chalk can be used to take both their places, at less frequent intervals. Quickly made heaps with plenty of green material in them will heat up high and fast, and kill weed seeds, fungus diseases and pests. Turning sides to middle is possible within a few weeks, and the heap can be ready to use in three months or less, but in any case not before it is dark and crumbly.
Capsids hatch at the beginning of the month and do great damage to dahlias, chrysanthemums, and all kinds of flowering shrubs by feeding on the growing points at the tips of the shoots and on embryo flower buds, the damage not being seen until at least a month later, when it is too late. So spray with a systemic or malathion insecticide in early May, and again to to 14 days later, treating the ground around plants at the same time, as these pests tend to drop to the ground.
Indoors, the greenhouse will be emptying of the half-hardy bedding plants, and pricked out seedlings, but tomatoes, pelargoniums, and chrysanthemums will be coming on fast. Tomatoes sown in heat in February will have been planted or potted last month and will now need regular training and sideshooting. Pelargoniums should be stopped as soon as possible; peppers and aubergines can be sown this month, so can primulas and cinerarias.
The greenhouse may need shading this month, particularly if tomatoes, begonias and gloxinias are grown; the increasing intensity of the sun will send the temperature very high very quickly, so give plenty of air during the day, but continue to close down to some extent at night, remembering that frost is still possible. Damping down greenhouse staging, and paths in the middle of the day, will begin to be a routine task, to maintain a humid atmrosphere, and discourage red spider mite. Humidity is essential for setting fruit and prevent bud drop before blooms unfold; it also prevents browning of leaf tips and leaf margins. Cactus plants should be given as hot and sunny a corner as possible; they revel in heat and light.
Cucumbers, marrows, celery and melons brought on and potted last month, can go out at the end of the month, into rich, well-prepared soils, though cucumbers and melons can also be grown in the greenhouse, and may do better there in cool seasons. They will need strong supports in that case, and regular training and tying in with removal of unneeded sideshoots.
Vegetable seed sowing can continue, of beetroot, ridge cucumbers, lettuce, radish, spinach, turnip, peas, runner beans and French beans.
Maincrop potatoes can still be planted out, and earlies will want ridging, unless grown on the flat, with a black polythene mulch. Weeds will need a good deal of keeping pace with, both among the vegetables and fruit, as well as ornamentals; they grow like wildfire this month. Broccoli will be finishing, so will spring cabbage, savoys, and late summer sown spinach, and the remains should be cleared off before they can provide homes for pests and diseases which can infect the new season’s vegetables. The larvae of the flies which attack onion, carrot and cabbage seedlings should be warded off with calomel dust on the soil around the plants, or trapped with baits of carrots and potato on skewers.
Quickly growing vegetables, e.g. the leafy kinds, will want a feed now, or regular weekly feeding with a liquid fertilizer; remember to water if the weather is dry, or to mulch on to moist soil so that the water supply is continuous throughout the life of the vegetables. If the district is a bird ridden one, protective matting is essential, both for vegetables and soft fruit. The fruit will probably not need protection until next month, unless it already is for bud pecking, but vegetables should be guarded sometime this month.
Strawberries will be flowering and setting; frosted flowers will have blackened centres, as will those of apples. Gooseberries and blackcurrants will finish setting early this month; if the flowering period is windy and cool, blackcurrants will ‘run off’, as bees will not work them in such conditions, and low temperatures inhibit pollination and fertilization. So give them a place sheltered from wind when planting, or put up a temporary barrier of sacking if the wind sets in from the north-east or south-west at flowering. There is still time to put straw on to clean ground. Spraying for greenfly, capsid, caterpillars, apple sawfly and mildew should continue. If dry weather occurs towards the end of the month, irrigate the raspberries, otherwise the new crop of canes will be severely depleted. Peaches will be stoning and should be thinned from the time they are about the size Of marbles, spacing them eventually to about 1 ft. apart, and spreading the thinning over several weeks.