Documents: Garden Design:

It Is All About Hydrangeas This Week
by Art Drysdale
by Art Drysdale

email: art@artdrysdale.com

Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at http://www.artdrysdale.com


October 25, 2015



Hydrangea paniculata ‘Limelight’, one of the newer hydrangeas; Hydrangea mac-rophylla ‘Nikko Blue’ an older cultivar that blooms only on old wood, therefore not particularly reliable in cli-mates such as Toronto. Below, Hydrangea ‘Endless Summer’ is one of several new cultivars which produce their flowers through most of the summer on both old and new wood; and finally Hydrangea macrophylla ‘Red Sensation’ just one of many newer cultivars. Author photos.




 



 

Michelle Luttmerding who lives somewhere in the Okanogan Valley of British Columbia wrote to Donna with the following question, and she has sent it on to me to reply.

“I have returned to your site hoping to find information on pruning hydrangeas. I have two new ones, one a lace-cap and one a regular one called Limelight. It has conical shaped flowers. They are both grafted I guess, they look like hydrangea trees. I cannot find anywhere on how to prune or when to prune so they will bloom every year. Any information you give me would be very much appreciated.

“I used to be a regular to this site and was on every Sunday for live chat with Art Drysdale. Wish that was back, I could have posted this question there. Never understood why it never took off.

“Hope all is well with you and Tom and that you do not mind that I am emailing you with this. Still gardening here in the Okanogan and now retired so our life is travelling and enjoying our new home which was just landscaped. Now I have more time for gardening.”

Well Michelle, first let me explain a bit about Hydrangea shrubs in general. Two decades ago a response to your question would have been easy and simple. Now, however, there are literally hundreds of new cultivars, many from varying origins.

The type of pruning required varies depending on whether the cultivar produces its blooms on new and/or old wood. Years ago, there were really only two types of plants—those such as Hydrangea arborescens ‘Grandiflora’ produced all of its round-ball-shaped flowers on new growth and that meant the pruning done was always severe (down to within 15 cm of the soil) in early spring; and those like Hydrangea paniculata ‘Grandiflora’ which produced its flowers on old wood, and required only a little pruning annually.

There was a third type of Hydrangea available: Hydrangea macrophylla which produced its flowers only on old wood, but most of the plants were not hardy in most of Canada. There were varying cultivars of this one available, which either produced blue-coloured flowers or pink ones—depending on the pH (alkalinity) of the soil in which the plant grew.

That has now all changed, and it changed over a decade ago with the introduction of H. m. ‘Endless Summer’ which produced its blue or pink flowers on both new and old wood, and was considered considerably hardier than the older macrophylla types (such as H. m. ‘Nikko Blue’) that were sold before it was introduced.

You have not said what the other cultivar that you have is, so it is difficult to recommend specific pruning. Cultivars such as the Endless Summer hydrangeas require very little pruning day-to-day, so you are able to simply enjoy the beautiful plants. These perennial hydrangeas bloom on growth from the current year as well as previous years, which allows for the re-blooming throughout the summer. If you prune too much, you will be removing potential blooms. If you prune to shape the plant or cut blooms for fresh hydrangea arrangements, be sure not to over-prune, or you will have less blooms next year.

As regards Hydrangea ‘Limelight’, it is not at all fussy, except that you should never prune it (or any hydrangea) in the spring or early summer when flower buds are developing. If you do this, you stand the chance of pruning off all the year’s flowers, and you will have to wait until next year to see any number of good flowers. Pruning in the fall should be all right for you in the Okanogan; however anyone reading this from severely colder zones (such at Ottawa/Montreal etc.) it would be best to hold off the pruning until after most heavy frost has passed the follow-ing spring, say after April 1.

You also mentioned you having participated on the weekly chat sessions on this site. We used to do them at Sunday mornings, and I hardly missed one even while on vacation! Tom Daw-son, and often his wife Donna used to participate weekly, but the response got to be very ‘thin’ and often we found the two or three of us just chatting to each other about various topics in-cluding the day’s news!

So in a consultation that lasted over several weeks, Tom, Donna and I reluctantly decided to cancel the chat but still answer any questions that were forwarded to us. And, sometimes when I am searching for a topic for one of my weekly articles I will consult the Forum section of the site and use one or two questions that arise there.

Happy gardening in your retirement!

   

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