7 deg C/45 deg F
Most hydrangeas sold as pot plants are forms ofH. macrophylla, many of which are named and have cream, pink or blueborne in large globular heads. The plants are specially grown and forced by nurseries, and appear in shops from mid-winter to summer. They will last in flower for a very long time, often well into autumn, if kept shaded, moist and cool, but they are not easy plants to save for the following year. After flowering, it is a good idea to plant it in the garden or in a large pot. It will then usually continue to grow and to flower. reaching an appreciable size. If you wish to try saving a plant for
further pot culture, cut off the dead flowers and weakafter flowering. Stand the plant outdoors in a shady – preferably with the plunged in moist peat – and keep moist during summer. Shoots that have flowered should then be cut back to a point just above a sideshoot. New shoots will produce flowers the next season, but to keep the plant neat and compact some may be removed cleanly. During active growth, give liquid feeds and treat blue-flowered forms with a special blueing compound available from garden shops. In autumn, when the foliage is shed. bring the plant into a cool room where the temperature does not exceed 10 deg C (50 deg F). Higher temperatures may inhibit flowering. Keep only slightly moist until
early February. The temperature can then be allowed to rise gently to encourage early flowering andcan be increased gradually. Saved plants will eventually become too large to keep indoors. If becomes necessary. use an acid , with some added peat if necessary.
When watering, use clean rainwater if the tap-water is hard and limy. Under alkaline conditions, blue varieties may turn pinkish or lose their rich hue. Do not attempt to turn normally pink forms into blue ones by using a blueing compound.
The most common pest is. If the is too alkaline, the foliage may turn yellow, as well as producing poor flower colours.