There are numerous ivies with ornamental leaves that make excellent pot plants for the greenhouse or the home. A great many of the kinds that are available are varieties of Hedera helix, the hardy common ivy. H. h. cristata is an interesting example with crimped edges to the green leaves. One of my favourites is Glacier which has silvery-green leaves with white margins. H. h. sagittaefolia is attractive; its small green leaves have pointed lobes. H. canariennsis, the Canary Island Ivy is more tender than the others but it is a delightful plant with large. Bright green leaves. It is usually offered in one of its variegated forms, like H. c. variegata which has handsome dark green leaves shading into silver and edged with white.
If carefully trained these plants can be use effectively to provide a pleasing foil for more spectacular plants.
The varieties of H. helix like cool. Partially shaded conditions but abhor draughts. Similarly, they will react adversely to hot over-dry atmospheric conditions which cause the leaves to wither and drop. They are happiest when the greenhouse temperature in winter is kept just below 10°C. (50°F.). Watering must always be done carefully, but especially so in winter. H. canadensis needs rather warmer conditions. All appreciate fairly frequent overhead sprayings with clear water.
Ivies are very easy plants to increase. Two methods are adopted – tip cuttings and leaf bud cuttings. The former are made from the tips of the stems. The lower leaves are removed and each cutting is trimmed below a leaf joint to make a cutting a few inches long. Several of these cuttings can be placed round the edge of a 3-in. pot filled with a mixture of equal parts of sand and peat, or seed sowing compost.
A leaf bud cutting consists of a leaf with a small piece of stem attached. This is cut just above and just below the bud in the joint of the leaf and the cuttings are rooted in a similar mixture to that recommended above.
Cuttings are best taken in the spring and summer and rooting soon occurs if they are placed in a propagating frame with a temperature of 16°C. (60°F.).
Once rooted, the young plants can be put in 2-in pots of John Innes No. 1 Potting Compost and later repotted into 3-½-in. pots. Ivies can be grown for some time in small pots if they are well watered and fed. Only when they are really pot bound need they be moved into 5-in. pots.