Garden Work for August

New Zealand Journal of Agriculture, Volume 101, Issue 1, 15 July 1960, Page 99

Garden Work for August

As the days become longer and warmer many more shrubs come into bloom.

Evergreen and frost tender shrubs and trees can now be planted, as the soil is beginning to warm up. If the soil is still cold and wet, it is better to delay planting, particularly on a clay soil; plants may be heeled in until the soil is workable. The ground should have been prepared at least a month in advance to allow the soil to settle again. During

By

JOY WATKINS,

Horticultural Advisory Officer, Department of Agriculture, Auckland

the preparation weeds are removed and compost or leaf mould incorporated. Before planting in positions where trees or shrubs have died "nd been removed it is advisable to treat the soil with copper oxychloride at 1 lb to 5 square yards to reduce the risk of fungous diseases infecting the new plants. Replants of the same type of tree or shrub are often unsatisfactory.

Herbaceous Plants Herbaceous plants can be propagated now. In colder districts or on heavy soils it is better to lift and divide these plants in early spring, as small divisions made in autumn are likely to suffer from cold and wet in winter before they have made much new root growth. The soil should be enriched with compost, manure, or leaf mould before replanting. Do not propagate from any plant unless it is vigorous and healthy. As the shoots of herbaceous plants begin to grow in spring, many can be used as cuttings. They should be removed with a sharp knife when 3 or 4 in. long, being cut just below a leaf or bud and any bottom leaves removed; Those with hollow stems (delphinium and lupin, for example) should be . taken with a heel of old wood attached. All types root more readily if the basal portion of the stem cutting was growing below ground before removal. Cuttings should be inserted in a light, sandy soil in a pot or frame and watered in. The atmosphere must be kept moist to reduce wilting by keeping the frame closed or enclosing the pot in a plastic bag until the cuttings are rooted. Cuttings consisting of small portions of the thick fleshy roots of such plants as gaillardia and oriental poppy will produce new shoots if inserted in sandy soil and kept damp. Most root cuttings grow successfully if placed horizontally and covered with their own depth of soil. Of the bulbs, freesias and sparaxis are now in full flower and make excellent cut flowers. Modern freesia varieties are much better than the old types and it is surprising that more are not grown, and they have a wide range of colours, long firm stems, and larger, less delicate flowers, which last a long time when cut. In the colder districts these bulbs should be planted in a warm, sheltered position in well drained soil. After flowering, do not cut back the leaves, as these make the food which will produce next year’s crop of flowers. Gladioli and other summer-flowering bulbs may now be planted in all districts. In the hotter and drier parts early planting is of particular value, as the flowers will be well developed before thrips become very active from the end of November. Gladioli are very susceptible to thrips damage, which causes distortion and browning of the flower spike, and a silverybrown discolouration of the leaves. Dusting the corms With DDT before planting will kill any of these pests in the early stages. Thiram dust can be added to protect corms from fungous diseases. Spraying with DDT 50 per cent wettable powder at 1 oz

in 4 gallons or lindane emulsion at j fl. oz. to 4 gallons of water every three weeks throughout the growing season will help to ensure that the plants remain free of thrips. When planting avoid hot, dry positions such as against the north wall of a house, as thrips multiply rapidly under such conditions, but do not plant in deep shade or the flower spikes will not develop. The soil should be well drained and enriched with compost and 4 oz to the square yard of a mixture of 3 parts of blood and bone, 2 parts of superphosphate, and 1 part of sulphate of potash. Plant at 4 in. deep and 6 in. apart. ' - ' Sowing Many annuals can be sown as soon as the ground is sufficiently dry and friable. Heavy clay soils which have been dug over roughly during winter can be broken down to a fine tilth with a fork. Such soils are most easily worked when they are drying after rain. Clods allowed to dry too much set hard and should be left until rain softens them. An application of lime immediately after digging in winter will often improve a clay soil. If seeds tend to rot or to be damaged by soil pests, they should be dusted before sowing with thiram and lindane. A small pinch of each shaken up in a packet of seeds is sufficient. Too much of either is likely to . retard germination. Pruning Prune peach, luculia, poinsettia, and similar winter-flowering shrubs, cutting back the branches which have carried the flowers to two 1 or three good buds from the base. Rose pruning should be completed and the bushes sprayed immediately with bordeaux mixture at 6| oz of bluestone and 5? oz of hydrated lime in 4 gallons of water to protect the pruning cuts from fungal infection. Bordeaux mixture at this strength should not be applied to bushes which have tender young shoots, but only to dormant plants. Glasshouse or House Plants As the nights become warmer growth of pot plants increases and those plants with roots which emerge from the drainage holes at the bottom of the pot have completely filled their pots and can be repotted. Most pot plants grow better if they are kept in the smallest pot commensurate with their top growth. Plants which have filled their maximum-sized pot can be kept growing by watering with a proprietary liquid feed every two or three weeks during summer. Alternatively use

sulphate of ammonia, dried blood, or blood and bone at 1 teaspoon to a gallon of water. Many plants, such as maidenhair fern and African violets, grow better when root-bound, that is, when the ball of soil in the pot is full of roots. The surface J to 1 in. of soil in the pot can be removed with a pointed stick when it becomes sour and greenish and replaced with fresh potting soil. Potting soil should be damp but not wet when used, and it should be of a sufficiently open texture to allow water to drain freely through it, but have enough organic matter to keep it damp for a reasonable period. Rotted turf, prepared as described on page 410 of the April 1960 “Journal”, should be mixed with coarse river sand, scoria, pumice, or similar drainage material, and leaf mould, peat, or compost in the bulk proportions of 3 parts of turf: 1 part of leaf mould: 1 part of coarse sand, though more or less sand can be used according to the texture of the rotted turf. Four ounces of a balanced fertiliser mixture and -J oz of lime should be added to each bushel (apple case) of soil mixture, which is turned several times with a spade to mix all the ingredients thoroughly.

Potting Place scoria or broken pieces of clay pot over the drainage hole at the bottom of the pot. Cover these with coarse leaf mould or moss to prevent blockage of this drainage . material. Add a little soil mixture and then place the small plant in the pot, adding and pressing down more soil mixture round it. The new soil must be packed as firmly as the old ball of soil round the roots; otherwise water will pass quickly through the loose soil without wetting the central firm mass in which are the roots. The surface of the soil should be level to provide for even watering throughout the pot, and it should allow sufficient space above so that when filled to the rim of the pot with water there will be enough to wet all the soil in the pot. This space is therefore about i in. in a very small pot up to J in. in a 4| in. pot. The plant should be at the same level in the soil as it was previously. Deep planting may cause rotting of the crown of the plant, while very shallow planting will expose some roots, which will dry out and die. When a plant is to be potted on (transferred from a small to a larger pot) it should be removed from the original pot by. tapping the rim on the edge of a bench, supporting the plant and ball of soil with the first two fingers. Carefully remove drainage crocks and loosen the mass of roots .at the base before potting as detailed above. Newly potted plants should be watered and then placed close together in a warm, shaded part of the glasshouse. As they begin to grow they can be spaced out so that the leaves are not touching. A damp atmosphere is beneficial if it is also warm, but cold, damp conditions encourage the development of diseases such as botrytis which can rot the leaves and crowns. Begonia and gloxinia tubers which were started into growth last month should be growing away well. Be careful not to water too frequently, as the roots are susceptible to rotting from overwatering. Ventilation and watering should be increased as the days become warmer, but care should be exercised, as sudden cold spells can check the growth of plants, particularly those which are in the seedling stage, and those which prefer warm conditions, for example, African violets and gloxinias.