HORTICULTURAL GLEANINGS.

Otago Daily Times, Issue 19958, 27 November 1926, Page 3

HORTICULTURAL GLEANINGS.

Tscful Hint to Rose Growers. —In cutting roses, cither for tho house or in removing dead ones, it is important to cut back a good distance, at least 6in, and past any spent shoot, to a visible bud in the angle of the leaf. This is practically summer pruning. The tree responds at once by sending out a flowering shoot, which flowers in a marvellously short time.

By adopting this plan of never “nipping” off dead Bowers, a correspondent of a gardening contemporary says his rose garden has been a continuous mass of colour with no dull period.

Giant Delphiniums.—A correspondent of The Garden records that a delphinium plant growing near the city of Durham had attained the extraordinary height of 10ft 2*in, and had 29 spikes on it.

Experiments in Potato Planting.—Mr G. E. Delong, of the Dominion Experimental Station, Lacombe, Canada, gives a summary of experiments in connection with the preparation of the seed and the methods of planting potatoes. He states that early planting produces heavier yields than late planting, and that large potatoes produce earlier crops than seed that is cut; the whole, large potato sends up stronger and more vigorous sprouts than small sots, and the sprouts seem to maintain their lend throughout the season. Moreover, large whole potatoes produce larger yields than smaller or cut sots. Experiments tubers approximately two ounces in weight planted 12m apart in duills made 30in to 36in asunder, gave the most economical results. The number of eyes per set appear to have little effect on the yield. The experiments showed that, in Canada at least, sin appears to be the most suitable depth for planting. The variety Gold Coin is most largely grown in Canada for the main crop, whilst Early Ohio is the earliest maturing variety.

Iris,—-The iris is now making New Zealand gardens gay with its stately and graceful blooms, although it is not yet at its best in these southern latitudes. In the herbaceous borders of Kew Gardens, in England, one of the finest of the tribe is I. Susiana, which in the month of May is a real picture. It is considered by leading experts that one of the chief essentials to sucess is the longest possible rooting period. As soon as the foliage turns brown, the rhizomes should bo lifted and placed in a dry shed to ripen. In New Zealand re-planting should not be later than May. Plant in a good loamy, welldrained soil, with plenty of lime.

Central American Plants. —Dr Paul C. Rtandley, botanist of the American National Herbarium, returned to Washington from Costa Rica in May last with a collection of nearly 12,000 plants, including 2000 specimens of orchids. He is preparing a memoir on the flora of Costa Rica, whilst the Smithsonian Institution is seeking funds to undertake botanical exploration in Honduras and Nicaragua. * * » *

Primula Obconica.—Plants of Primula obconiea raised from seeds some time since should be pricked off or potted on as they* require it, while further sowings according to requirements may be made this month in New Zealand, as this useful primula may be had in flower more or less .'ill the year round. Those who suffer skin irritation from contact with this plant should on no account handle it, as much discomfort and even serious illness may result; some writers contend that the present-day strain is not so poisonous as the original types. It is unfortunate that such statements should be made, as the plant is just as virulent as ever, and at Kew the assistant-curator says they are seldom or ever without workers who cannot handle this plant without being affected by it.