Hydrangeas are some of the most hardworking, carefree shrubs available. With little to no attention, they’ll reward you with loads of large, long lasting, and spectacular blooms. Specific care varies, depending on the type of hydrangea.
Macrophylla include both the mophead and lacecap varieties. Mopheads, or Hortensia types, have large, dome-shaped flowers, generally in some shade of pink or blue. Popular examples are ‘Nikko Blue’ and ‘Big Daddy.’ Lacecaps, or Mariesii types, have flatter blooms with a fuzzy appearance in the center. An exceptional variety is ‘Mariesii Variegata.’
One consideration when caring for Macrophylla is soil pH. Flowers turn bluer in acid soils and pinker in neutral to alkaline soils. Your soil type is easily determined by using a soil-testing kit, available at most garden centers. There are commercially available products that help control soil pH if you happen to have one type of soil but desire the opposing color flowers.
Most types of macrophylla bloom on old wood; that is, last year’s growth, and improper pruning can cost you next year’s flowers. It’s okay to remove dead wood or spent blooms at any time, but more drastic pruning should be reserved exclusively for June or July, before next year’s buds have set. Macrophylla generally require no pruning, however, except in the case of very mature plants whose branches have grown long and leggy, causing flowers to droop to the ground.
Some types of macrophylla bloom on new wood, however, called ‘remontant’ or ‘ever blooming’ hydrangeas. ‘Endless Summer’ is a popular example of this. While this shrub can be pruned more aggressively than other mophead or lacecap varieties, it does not require it.
While technically a macrophylla, arborescens bloom on new wood and can be pruned anytime other than spring, making it a favorite for northern gardeners with winters severe enough to kill buds on hortensia and mariesii varieties. ‘Anabelle’ is a very popular variety. Even though you can prune arborescens, it doesn’t mean you should; excessive pruning will lead to thinner stems less able to support the large blooms. If you must prune arborescens back, support new growth with small pieces of wire fencing or some other staking apparatus. Soil pH is not a consideration; flowers are light green turning to white.
Commonly called Oak Leaf Hydrangea because of the shape of its leaves, quercifolia has large, long, pyramid-shaped blooms. ‘Double Snowflake’ and ‘Snow Queen’ are popular varieties. Blooming on old wood, its pruning requirements are the same as macrophylla. Soil pH has no effect on bloom color; all flowers are white.
Also called PeeGee Hydrangea, these are identified by their large, showy, conical flowers. ‘Limelight’ is a popular variety, and PeeGees are the only type of hydrangea that can be trained into tree form. Paniculata bloom on new wood and can be pruned anytime other than summer. Some pruning will help to improve the fullness of a plant, although this need not be done every year. Soil ph is not an issue; flowers are white turning pink.