Pot-plants which were repotted in early and mid-spring will have used a good deal of the nutrient in the compost, and regular liquid feeding can start from now on, unless they have grown so much that repotting or potting on is necessary. Hippeastrums should be fed, together with any other spring bulbs still growing. For really prizewinning sweetpeas, liquid feeding will do wonders, though with good trench preparation during winter, they may be growing so fast that extra feeding is unnecessary. Lawns growing on light soils will need a powder feed at half the normal rate, applied when the soil is moist and watered in; little and often is the guide to feeding turf on sandy or ‘hot’ soil. Cacti do not need feeding unless they were not repotted in the spring and then only once every four weeks or so.
The border peony, with its lovely colouring and full-blown /lowers, is the personification of early summer.
Most plants that need staking will already have been secured but border carnations will develop their rather floppy and comparatively long flowering stems during the next few weeks. A little help in standing up will mean a better display but don’t tie them rigidly to the supports right up to the buds; otherwise they will lose much of their charm. Stake freesias if not done already.
Continue to tie in chrysanthemums, dahlias, delphiniums, lilies and sweetpeas as they grow and keep an eye on other tall-growing plants which may not be as sturdy as they look. Sweetpeas may begin to develop flowering stems towards the end of early summer in warm gardens; watch for the embryo flower buds at tips of the stems, otherwise you will be removing them automatically as sideshoots.
Early- and late-flowering varieties of chrysanthemums will need stopping; violets should be de-runnered, otherwise the parent plants flower less well. Take the runners off with as much stem as possible.
Some plants – such as polyanthus, auriculas and primroses -can be increased by division in early summer. You will find that they have produced plantlets at the side of the parent crown; these can easily be split off with roots attached, replanted in a shady place until autumn and then planted where they are to flower.
Bearded irises can be lifted after flowering and divided every four or five years, otherwise they get crowded and flower badly. This is the time when they grow new roots, so dig them up, keep the new younger root or rhizome and throw away the old central crown. Replant so that the rhizome is only just below the soil surface; a little showing above the surface does no harm. Bonemeal mixed into the soil before planting at about 120g per sq m (4oz per sq yd) will help the roots.
Continue to hoe or use weedkiller to keep weeds at bay. By now duckweed and blanket weed may be starting to grow in pools; duckweed is the tiny, light-green, one-leaved floating weed which collects in large groups on the water surface and blanket weed is the long, hair-like, dark green strands which grow submerged in the water. Chemical control in garden pools is not possible as cultivated plants will also be damaged, so frequent raking all through the growing season is necessary to keep these two water weeds under control. In pools well stocked with goldfish and freshwater winkles, the blanket weed will be eaten.
Continue to mow the lawn, deadhead unless seed is required, water outdoors (do not forget freesias) and in the greenhouse and build the compost heap. Keep the greenhouse well ventilated and damped down.
Greenfly and capsid will continue to be a nuisance, various caterpillars will be about, including one rather beautiful velvety green kind which lives mostly on delphiniums, and Sawfly larvae feeding on the leaves of Solomon’s Seal (Polygonalum multiflorum). A pernicious new pest is leaf-miner, which can do surprisingly bad damage, considering it is such a minute larva. The maggot hatches from eggs laid in the leaf tissue and feeds in the tissue, making winding, pale-coloured lines (tunnels) or pale-brown blisters as it moves about. Leaves can be so badly infested that they wither completely; chrysanthemums and cinerarias suffer badly. They will also be found on a variety of other plants but if the plants are growing in the ground they will not suffer so badly; it is the potted plants which seem to have little resistance. Remove affected leaves and destroy and spray the remainder with an insecticide.
Sometimes flea beetles attack seedling and young wall-flowers but an insecticidal dust applied as a precaution will solve this trouble; the symptoms of infestation are small round holes in the leaves and tiny, hopping, dark-coloured beetles. Whitefly, small white, moth-like creatures, can become terrible pests on greenhouse fuchsias, usually if the plants are kept too dry and hot. Likewise red spider mite on most greenhouse plants; it feeds on the sap, mainly in the leaves, and makes webs. A hand lens will show the light red, round adults on the undersides of the leaves.
Damping down the greenhouse keeps it more or less free of pests as well as cooling it and making the air humid. Mealybug is another greenhouse dweller, partial to hippeastrums but not averse to other potted plants. Blobs of white fluff on your plants are highly suspect and are likely to contain the bug, feeding on the sap.
Rust fungi can be a problem on such plants as hollyhocks and antirrhinums, pinks and carnations. Although they are not as widespread as the insects mentioned, they are very damaging where they do occur, resulting in early leaf-fall, and poor, stunted plants. Symptoms are raised, bright brownish-red spots on the under surface of leaves, easily missed until it is too late. Grow resistant varieties if available, avoid crowded conditions, and hand-pick diseased leaves, following with a fungicidal spray.
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