Hydrangea macrophylla
Hydrangeas are popular ornamental plants, grown for their large flowerheads, with "Hydrangea macrophylla" being by far the most widely grown with over 600 named cultivars, many selected to have only large sterile flowers in the flowerheads. "Hydrangea macrophylla", also known as bigleaf hydrangea, can be broken up into two main categories; mophead hydrangea and lacecap hydrangea. Some are best pruned on an annual basis when the new leaf buds begin to appear. If not pruned regularly, the bush will become very 'leggy', growing upwards until the weight of the stems is greater than their strength, at which point the stems will sag down to the ground and possibly break. Other species only flower on 'old wood'. Thus new wood resulting from pruning will not produce flowers until the following season.