Care for climbing hydrangea


My climbing hydrangea is about 20 years old. It is in my garden on the side of your garage. Each year the leaves and and the beginning of blooms return, however in the last few years the blooms have failed to open and display their white flowers. Also there is a pest that is always present that eats its leaves. I have sprayed an insecticide on it when I notice the leaves being eaten, but can not get on top of the problem. Your advice about the insect problem, fertilizing, and other care instructions to promote the white flower blooms to display would be appreciated.


Thank you for contacting us about your problem with climbing hydrangea (Hydrangea petiolaris).

Without more information, it is hard to determine why your hydrangea is not blooming, especially since it has been in place for 20 years and has bloomed before (a common issue with climbing hydrangeas is that they do take a few years after they are planted to become established and begin blooming, but that does not seem to be your case).

Some issues to consider:

  • Pests — you mention pests eating the leaves:  this could be aphids, mealybugs, scale, earwigs, slugs, Japanese beetles or a host of other insects. Unless the leaf damage is severe or the pest is affecting the leaf buds, and without further information, the vine should be able to tolerate some mild infestation. It is not advisable to apply  broad-spectrum insecticides, or indeed any insecticide at all, before you have determined what the pest is. Most insecticides (including neem oil and home remedies) also kill beneficial insects that might act as a natural control to whatever is eating the leaves of your hydrangea. Use a hand-held 10x magnifier to try to figure out what the insect pest is (or it may be a fungus or bacteria) and note in specific detail what you see, ie, shape and size of holes; sticky sap; watery or other spots; any kind of film or webbing, etc. A camera that allows you to zoom in would also assist in taking close-up photos. Once you have a better idea of what this pest is, you can try to manage it.
  • Fertilizer — is the plant getting too much fertilizer?  In particular, is it getting too much nitrogen (the first number in a fertilizer formula, e.g. 20-5-10)? Excessive nitrogen produces leafy growth at the expense of flowering. Please be aware that too much organic compost can also produce the same result, as compost is high in nitrogen. Most garden beds only require 1-2 inches of compost per year (see link to Compost Council of Canada recommendations below), and many plants also do not need more than this.  Use of fertilizers should be a well thought out decision, because nutrients can run off your property and into waterways, where they can have a negative effect on aquatic life. (Many gardeners have adopted a more eco-friendly approach, and no longer use fertilizers of any kind, even  — and especially — bone meal.) Also leave plant trimmings, twigs, leaves and other plant debris to decompose naturally. You will have to decide for yourself whether you wish to add fertilizer or not.
  • Light — are there nearby trees/shrubs which have grown taller, wider and have started shading the vine?  Climbing hydrangeas tolerate shade, but if they are now getting heavy shade, this could impact flowering. Conversely, the loss of a nearby tree could also affect blooming because the vine has suddenly had to adjust to more light than it previously received.
  • Water — is the plant getting sufficient water, or conversely too much water?  Both of those things could affect flowering, because both deprive the plant’s roots of oxygen and water. Our summers have been getting hotter and drier, and it is possible that your watering regimen is not keeping pace with regional climate changes;
  • Root damage —  sometimes damage or other changes to the root zone could affect flowering.
  • Pruning — have you been pruning the vine differently from the way you have in the past when it was still blooming? In general, unless it is to remove dead or diseased material, you should probably wait until after the vine has bloomed to do any pruning, especially severe pruning or pruning for shape.

Please see links below to help you in your journey of discovering what might be the problem, but keep in mind that it is in fact a journey and there could be multiple factors at play.


The – growing climbing hydrangea

Royal Horticultural Society – Hydrangea scale insects

Toronto Master Gardeners – issue re climbing hydrangea blooms

Gardening Know How – Climbing Hydrangea Won’t Bloom

Home for the Harvest – Climbing Hydrangea Problems

Gardeners World – how to grow climbing hydrangeas

Compost Council of Canada: The Secret to Successful Living – Healthy Soil