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Burdock, Hydrangea, Canna, Calla, Grub Control

Getting rid of ‘sticky bus plant’; about planting Hydrangea arborescens ‘Annabelle’; Canna and Calla lilies in ponds; more on ineffectiveness of nematodes for white grub control in lawns; and a final comment about my Escallonia shrub!
by Art Drysdale
by Art Drysdale


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

May 10, 2009

Above, Sticky bus plant or Common burdock (Arctium minus) in all its glory (!); and a typical flower cluster on an ‘Annabelle’ Hydrangea. Below, shots of a Canna growing in our large pond here, and a Calla lily growing near the same pond’s edge; and finally a shot of what our Escallonia Pink Princess looks like in a good year, plus a shot of the newly emerged growth from otherwise dead branches. Author photos.

Several interesting questions this week--you can tell that the official outdoor gardening season is almost in full swing! The first one came to Donna Dawson from Leslie Oke, and I had to write and ask her whether or not she had a more accurate name, and could she send a photo. It turned out her first suggestion of an alternate name was correct, but I did not see any connection between the proper (?) common name and what she called it--sticky bus plant! Here’s what she asked: “I have what we call sticky bus plants in my back yard. I do not know the official name maybe burdock? How can I get rid of them? I have tried to collect the buds in the fall and cut them down but the stalks and buds come back. Any suggestions?

So, she was correct, it is common burdock (Arctium minus). It will have light-mauve/purple flowers followed by the infamous ‘burrs’ that so easily attach to clothing when walking near the weed. It is difficult to kill without the use of an herbicide, although it can be done, even if the plants achieve shrub-like status which many do. The most important point is to remove the flowers as soon as they are noticed so no more seed will be set--burdock spreads only from its seed which is generously produced. It is equally important to dispose of any burrs found in an animal’s hair so the seeds within the burr are not deposited in a garden area.

Burdock will respond well to Roundup, but it works best if applied to a young rosette of basal leaves. If the plant has already bolted to quite a height, the best is to cut it back to the ground and let a new basal rosette develop, and then treat with Roundup. I would buy the liquid concentrated product, mix it in a plastic container at a rate two or three times as strong as recommended, and then apply it to the foliage with an old paint brush.

The next question came from Margaret Kerr of undetermined location. She asks: “I wonder if you can help me with an answer to some questions about Hydrangeas. I plan to plant 5 or 6 Annabelle Hydrangeas along the front of my house. How far out from the foundation should I plant? What spacing should I do between each plant? When planting these (which will be bare root plants dug up from a huge plant I planted years ago that has produced lots of new plants) - should I add Triple Mix to the soil?

“Annabelle is, I believe, H. arborescens, Smooth Hydrangea and it grows up to l 1/2 metres tall. Any help you give me will be greatly appreciated.”

While I do like the ‘Annabelle’ Hydrangea, I am not sure that I would recommend a row of six of them along the front of a house. They are rather blah during the entire winter season. That comment actually applies to any Hydrangea as far as use in a foundation planting is concerned. I would definitely recommend some type of evergreen that would give you something to look at throughout the winter season as well. If not an evergreen, then consider a de-ciduous shrub such as any one of the dogwoods that have red or yellow stem colours, or Kerria which has green stems.

As regards the triple mix or equivalent, I would not likely add that to the planting soil. Most of those mixes are not really very good, and certainly do not meet any particular standard. It would be better to add your own compost, or Canadian sphagnum peat moss, or Coir. As to distance for planting the Hydrangea, I would certainly not put them closer than a metre (39”) apart, and try for that distance as well out from the wall.

The next one came from Christine who has a good idea: “I'm living in Toronto area and I successfully grew Canna Lilies in pots standing in my pond in the past years. This year I would like to try Calla Lilies in the same manner (by the descriptions of requirements I found on the internet they seem to need similar conditions). My pond is approximately two feet deep and sits mostly in the sun. What are your thoughts on that? Should I give it a try? Thank you very much.”

No problem with that Christine. In checking my file of photos taken of our ponds here, I find I don’t actually have any shots of Calla lilies growing in a pond, but I do have a shot or two of one growing in one of the pond-surround plantings. I’ve included that here, as well as one of a nice ‘Johannesburg’ Canna in our large pond. Basically it will do best if the top rim of the pot is made to sit just at the water surface. Good Luck!

And from Brampton Ontario Chris Gavaris wrote asking: “Just read your article on grub control, and agree whole-heartedly with what you stated about the use of nematodes. We have been faithfully using the nematodes approach for the past three years and our lawn has gone from bad, to disaster! It is May 7th and I am not sure if it is too late in the season to use CIL's GrubOut with Sevin. The raccoons and skunks are having a feast every night; if we do not do something soon at this rate we will have little lawn left to worry about. Your perspective would be much appreci-ated.”

You, obviously are further proof of what I said back in May 2006--that I do NOT recommend nematodes for the control of white grubs ( ). I do think it is slightly too late for GrubOut to have much effect on the grubs; however, the mere fact that the raccoons are still dig-ging in your lawn is indicative that many of them may still be in the upper surface. So, I would take a chance with the GrubOut. Obviously, you are aware that such an application is contrary to the Province of Ontario’s new Cosmetic Pesticide Legislation and the product is no longer allowed to be sold (or used)!

Finally this week, a report from my own garden. All spring season I have been mentioning a number of plants (trees, and shrubs generally) in our garden here that looked very much as if they had died over our hard winter. For inquiring gardeners I said that I recommended treating such plants with a liquid application of soluble fertilizer (from a hose-end sprayer) and that is what I did here as well. Now, just a little more than two weeks after my first spraying of 15-30-15 I note that one shrub in particular appears to be coming back. That would be our Pink Princess Escallonia (Escallonia x exoniensis ‘Frades’). This is a broadleaf evergreen that blooms reasonably continuously through the summer, and it seemed a shame to tear it out prematurely--although thousands of gardeners out here appear to have done just that. Now, in the last photo accompanying this article you can see from the photo that my Pink Princess is indeed coming back. I also note that one of my rock roses (Cistus purpureus) is also showing new green sprouts from branches that once appeared dead.

Now, if I could only see signs of growth on my Sophora ‘Sun King’, Peruvian potato vine (Solanum crispum glasnevin) and Mitraria coccinea I would be oh so happy. Unfortunately all three appear to be dead!

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