Plant Doctor Archive

Pruning hydrangeas

I HAVE a hedge of hydrangeas. I live in an area that is quite prone to heavy late frosts. When is the best time to prune my hydrangeas and how should I go about it? Can I use hedge clippers?

YOU could take to your hydrangeas with hedge clippers - they would survive and grow away all right, but you wouldn't get nearly as many flowers. It would also encourage thin, whippy growth that wouldn't flower well next year.

Hydrangeas can tolerate frost, but once spring growth has started, a heavy frost could knock them back a bit, so put off pruning until you feel the risk has gone. Then cut out any thin, weak shoots at their base. Next, cut back the shoots that flowered last year (the remnants of old flowers should still be visible) to a pair of nice fat buds close to the top of the shoot which should produce flowers later this year. Make sure to choose the fattest buds, as small ones are less likely to flower. Don't touch any of the shoots that didn't flower last season, unless they are weak or broken, as they should produce this season's first flowers from their tips.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.