Except in very cold, exposed gardens, many hydrangeas are hardy if planted in sheltered positions in deep, rich, either from October to November or from March to April.
Varieties that are blue on acid soils are usually pink or crimson on alkaline soils, and as they are so attractive it is scarcely worth trying to blue them with aluminium sulphate as is so often recommended, since large quantities applied at frequent intervals are often necessary. Some kinds never blue.
The lace-cap varieties with flat heads in which the outer rings of sterilecontrast with the inner small fertile flowers are very attractive.
Drasticis not needed, but last year’s shoots of Hydrangea paniculata grandiflora can be cut by half in early spring.
Hydrangea macrophylla, up to 10 ft., and its many varieties, are the garden hydrangeas, with large globular heads of white, blue or pink flowers in June or July.
H. paniculata grandiflora, 7 to 8 ft., pointed spikes of creamy flowers in August and September which turn pink as they age.
H. villosa, 6 to 8 ft., hairy leaves, and flowers in flat heads with bright blue fertile flowers in the centre and large, flat, lavender-blue ones on the outside. The flowers are borne in August.