Plant Doctor Archive

My Hydrangea won't flower

I have a Hydrangea quercifolia. Last year it was planted in the shade, but it was hidden and couldn't be seen clearly. I moved it after I had cut it back and now it has about half a day's sun. It looks well, robust and it's a good size, but it hasn't flowered. Please tell me what to do.

There could be a couple of reasons for your hydrangea not flowering. Hydrangeas flower on the previous season's growth, therefore this season's new growth will flower next season. By cutting your hydrangea back, you have cut out the flowering wood. Next season it should flower.

When pruning hydrangeas, l like to wait until early spring when the buds start to swell. This makes it easier to identify the fat, swollen flowering buds as opposed to the slender elongated foliage buds. Prune to 1 cm above the fat swollen buds.

If the foliage is lush and green, this indicates your soil may be high in nitrogen — mulch, compost and lawn clippings are all good for the soil, but are high in nitrogen. A side-dressing of Sulphate of Potash will help promote flowering. Autumn is a good time, and then again in early spring when the plant bursts into leaf.

Alternatively, use a general garden fertiliser or controlled release fertiliser such as Osmocote, applied now and again in spring as a side-dressing.

Hydrangeas like light shade, a cool, moist, well-drained soil — mulching is beneficial.

Advice by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor of Resource Management.

Reproduced with permission from NZOOM Home and Garden content, from the previous website of  The views expressed here are not necessarily those of the RNZIH   HOME AND GARDEN   Plant Doctor Archives Main Page