Dahlia: Growing Guide

Tuberous-rooted perennials, imported into Europe from Mexico as early as 1600. Botanists soon started to cross the existing species and an enormous variety of large-flowered garden forms has been developed. None of them are winter-hardy, and the tubers must therefore be lifted every winter to be kept in a frost-proof place.

Situation:

Dahlias are used on a large scale as summer-flowering garden plants, especially together with annuals in beds. Not everyone appreciates the vivid colours, which make it difficult to combine dahlias with other flowers – herbaceous perennials for instance. In that case it is best to confine dahlias to beds of flowers for cutting, especially the tall-growing strains which must be sup-ported by stakes or by coarse netting spread over the bed when the plants are still small. There will be flowers for cutting until well into autumn.

Soil:

Dahlias require good garden soil, enriched with rotted stable manure, dried blood or, if necessary, with artificial fertiliser.

Propagation: and culture Dahlias may be grown from seed, but this method will produce an odd mixture, which may nevertheless include very fine specimens. Sow from early spring onwards in a temperature of 18°C. Prick out the seedlings and grow them in a cold frame until they are moved outside in late spring.

Division of the tubers or propagation from cuttings is a more usual method. In early spring the tubers are laid in trays or boxes filled with peat fibre or light garden soil, kept at a temperature of 15°C. When the tubers start to put forth shoots they may be cut up in such a way that every section bears a shoot. The cut surfaces are left to dry out and dabbed with charcoal or with a fungicide. The sections are potted separately and are initially kept under glass. In order to take cuttings, the tubers are also allowed to start into growth at a reasonable temperature. Remember that the first few shoots will produce the worst plants; unless you wish to grow a large number of plants, these are therefore discarded. The next few shoots are allowed to grow to 5-7 cm and are then severed close to the tuber. The lower leaves are removed and the cuttings are inserted in a mixture of sand and peat, under glass, in a temperature of 15-20°C. Make sure that the succulent stems do not rot and keep them in a frost-proof place.

Dahlias are very sensitive to frost and should preferably not be moved outside until late spring. If there should still

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