Dahlias are undemanding

Press, 26 September 1980, Page 8

Dahlias are undemanding

GARDENING

M. Lusty

In the modern garden dahlia we have a plant whose widely ranging forms, sizes and colours, provides us with a wealth of marvellous variety .to brighten up the scene, whether inside or outside, over and during the summer and autumn months. Dahlias are divided into two main groups: the bedding dahlias, which are raised as annuals from seed; and the border dahlias which • are nredominantly grown from tubers, but also from cuttings.

There is nothin? difficult associated with the growing of good dahlias for basic requirements; Subsequent cultural attention is not demanding. For best results, give them a good sunny position, adequate drainage, and plenty of well-rotted organic matter in the soil. Shelter from strong winds and staking must not be overlooked as may be the need for lime if the soil is on the acid side.

During the season, watering, tying-in, and some pest control will be inevitable for success. The disconcerning grower will also attend to disbudding.

Border dahlias do not breed, true to type and so the very, simple form of propagation by means of tuber division is carried out, usually on an annual basis. Cuttings taken from basal shoots, provide an alternative method but this is a much more demanding method of increase.

■. Where drainage is reasonably good throughout the winter, there is no problem in leaving the plants in the ground until early Spring before lifting, dividing, and replanting: the tubers. There is little advantage, if any, in planting out in a cold soil. Late October is. time enough to get things underway. ' During the flowering season, the best and most appealing dahlias can be noted, and only the best are worth.growing. Clumps which have started to sprout provide a useful indication of life in the tuber, but this is not to say that those indi-

viduals which have not as yet shownsigns/ of movement should b'e discarded if otherwise healthylooking. When dividing up with knife and secateur, be sure to leave the neck section attached to every tuber intended for replanting and at least one. shoot or eye for without these appendages nothing ,will come of if and it will end up by rotting away, - • There is something to 1 be said for avoiding . the retention of the biggest tubers unless they are reduced in size from the basal end, as they /are otherwise inclined to be the slowest to commencegrowth. A dusting- over, with a fungicide such as sulphur, and an insecticide such as lindane, can be

of help in preventing disease and insect damage. ' Drive a stake into the ground before planting each tuber and then also attach a name tag to it. It’s very helpful to be able to identify what you have growing without lingering doubts as to its exactness. About 100 mm is a suitable depth to plant most dahlia tubers, allowing another 25mm in very light soil. Make sure that the tuber is firmly bedded in the soil and not suspended, as it were, in a virtual air pocket. . When growth is about 250 mm high, pinch out the terminal bud to, induce lateral .'growth. Do not overlook tying up the growing plant: use soft material such as panty hose which has plenty of give in it; Watch for aphids, caterpillars and powdery mildew,and apply a control as soon as there is any sign of any or all of these debilitating invaders.

Dahlias -respond to moisture, and good watering as required should be maintained throughout the later seasons.

Colour of blooms can be improved and quality enhanced by the addition to each plant of an egg cup full of magnesium sulphate (epsom salts) and a sprinkle of potassium sulphate, both of - which should be applied in early January. Disbudding is necessary if it is desired to exhibit blooms, or where better quality is wanted. Flowers usually appear in groups of three. To disbud, the centre one is-' retained but the ones on either side are pinched off when the size of a pea. Spent flowers should be removed promptly by cutting back to a leaf junction, not to mid-stem, which can induce die-back.

Foliage should be left for the frost to blacken, and can then be cut down.