How to Trim Mophead Hydrangeas
- 1). Remove weak spindly stems -- thinner than a pencil -- at the base of the hydrangea shrub. Do the same with twigs that broke too close to the ground or that are mostly diseased, with very little or no healthy tissue left.
- 2). Prune healthy stems that have flowered back to the last set of buds. Do not prune strong stems that haven't produced flowers. Make all pruning cuts ¼ inch above a pair of buds, unless you are completely removing a cane. Prune the stems at a 45-degree angle with an upward slant.
- 3). Rejuvenate an old mophead hydrangea by completely removing all dead, weak, broken and diseased stems at the plant's base. Prune all healthy stems, regardless of whether they have flowered, back to the last set of buds. Your shrub will skip a season before it starts flowering again after this hard pruning.
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