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Row Covers, Pruning, Ants & Cats

More on Row Covers re carrot rust fly/onion maggots; just when to, and when NOT to prune lilacs; what possibly to do with lily-of-the-valley that do not flower; controlling carpenter ants; and finally CATS!!!
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 22, 2005

Last week’s mention of row covers had a number of people wondering about them, above is an example from the Johnny’s Selected Seeds catalogue; and below, several correspondents this week mentioned the 105-year-old Rhododendron ‘Cynthia’ that I showed in one of my Shaw TV segments here on the is-land last week. Here is ‘Cynthia’ with me almost hiding on the right (!). At bottom two shots of my Silent Yard-man lawn mower of late 50s vintage. All I need is a replacement roller support for the right-hand side (that’s the one from the left side in the last photo).
Author photos.

Last week, in response to Alice Bates’ question about a replacement for granular Diazinon as a prevention for carrot rust fly, onion maggot etc. I gave a lengthy response that included mention of row covers. I said Humber Nurseries in the Toronto area carried these. But, I did not give any other suggestions as to where they could be obtained. If you are not in the Toronto area, you should check your seed catalogues--many seedhouses do carry row covers. For example, Johnny’s Selected Seeds located in Winslow, Maine, has a line called Agribon+ and their AG-12 type (made of spunbonded polypropylene, admits air, 90 percent of the sunlight, as well as rain and irrigation moisture) is specifically designed to exclude insects. As mentioned, it must be put on immediately after sowing the seed. It comes in eight-ft. widths by various lengths from 50 feet up. Obviously it can be cut in narrower widths if desired. And remember, I said last week that it is important to have the row cover tight with the ground, and you can either do this by using special tacks (such as are sold by Johnny’s) or by covering the edges with soil all along the run.

Let’s take a look at some of the most recent questions, such as this first one from Sheri, located somewhere on Vancouver Island. “Hello Art: Just saw you doing something on a gorgeous plant (‘Cecilia’ the 105-year-old Rhododendron) in Ladysmith. I was wondering, we have a beautiful old lilac bush, about 7 feet tall. It has al-ways produced an enormous amount of flowers, but my husband decided to trim it down this year, about February or March, I think. Anyway, we got no flowers on it this year. Will it produce next year, or has he pruned it too early and stopped it's growth?”

Well Sheri it’s all your husband’s fault, but then you should have told him not to prune a lilac at any time but immediately after the flowers are finished! That means that here on Vancouver Island right now is the time to prune lilacs. By pruning early this spring, what he actually did was to remove virtually all the flower buds for this year before they had a chance to grow.

Pruning lilacs requires essentially the same caution as when pruning the dead flowers off Rhododendron shrubs. You cut off the old flower heads, but you must note the two little buds that are emerging from just be-low the old flower heads. Be sure you spot these before making each cut. Do not cut or damage either of the two little buds developing. These are next year’s flower buds yet to develop.

The pruning your husband did early this spring, while it meant you had literally no flowers this year, provided you do NO pruning now until after it blooms next year, there should be a good display of bloom next year.

And then we have Linda in nearby Lantzville who said: “Dear Art, Was watching you on Shaw Cable from Lantzville and thought you would be the one to ask. I planted Lily of the Valley plants 8 years ago when we moved into the house (among many other plants and shrubs, of course) but have only had a few of them flower. The plants are spreading, which is fine, and the leaves are healthy, just no flowering, therefore no beau-tiful perfume filling the air. Any suggestions? They are planted on the north side of the house just under our front window.”

This is the first time ever that I have had this question; generally with lily-of-the-valley (Convallaria majalis) the problem is their spreading and taking over entire gardens. To some gardeners they are almost as bad as goutweed or variegated ground alder (Aegopodium podagraria ‘Variegatum’). My friend Larry Sherk who grows a few lily-of-the-valley in Toronto says he has a somewhat similar problem, in that not all plants (or pips) bloom every year, but he has no way of telling whether some plants bloom every year while others never bloom, or if all the pips bloom irregularly.

While lily-of-the-valley likes shade, they also like a little sun, especially in the AM. I would try some in a slightly sunnier area, and be sure to fertilize them all soon now with a high phosphate fertilizer (something like 15-30-15). They grow from little pips, which you could try moving to a different area to see if there is a better response with more light. Also, they likely will do better in a lighter rather than heavier soil.

“We have a huge problem with carpenter ants, they have taken Diazinon off the market which really worked, now they have this white powder stuff out friendly to pets etc, it does not do a thing, is there a good home remedy that will do the job, please I need help fast.”--so says D&L Baxter, of unknown location. Again, my own problem with these, soon after we acquired our house here in Parksville, was quickly solved through the use of Doktor Doom Residual Insecticide Spray. We find that it has an effect on insects often long after the 60-day residual period has passed. Check the Website for a dealer near you.

Denise Parisian in Regina Saskatchewan (I noted it being pronounced “Regeena” on CNN this week, in connection with the Queen’s visit!) wrote as well: “Hope everything is well with you. I’m hoping you can help solve this problem we seem to be having with the neighbourhood cats. Almost every year, when we anxiously await our flowers to pop up, it seems there are less and less surviving. The problem is with cats in the neighbourhood--they come into the front flowerbeds and either “do their business” in the dirt, or dig up our bulbs. We heard coffee grounds were good for that, so we tried it--to no avail. Then someone advised they heard that cayenne pepper would keep them out of the beds. We bought masses of it in bulk, and it didn’t work either. Do you have any suggestions? It is not our intention to harm the cats in any way, just [get them] to leave our flowers alone! Any hints you could provide would be very much appreciated.”

I call this “the cat problem” and it is not unusual. Back in the late 90s, there was a ‘new product’ called the Skit which seemed fairly effective but I have not seen it for many years now. I’ll quote what I said in the past: “The Skit is a simple clear plastic device that screws into a white plastic base. It is placed in the garden where the cat frequents. The cat sees itself in the water-filled clear plastic and thinks there is milk in it (the water looks like milk), and not wishing to defecate near a food source, goes elsewhere. The point of this device is not to keep cats out of a garden, but rather to stop them defecating there. If the cat moves to another spot in the garden, the Skit is simply moved to that area until the cat goes to another garden!”

“Another so-called solution that has worked for a number of gardeners is to place clear plastic two-litre soft drink containers (filled with water) upside down in the garden where the cat(s) frequent. The idea is that the cats see themselves in a ‘mirror’, do not like it, and leave.”

“More sophisticated solutions do exist, but I have not seen them (that doesn’t mean they are not available) in Canada. For example, the Liquid Fence Company in Brodheadsville, Pennsylvania 18322, has several products, for the control of rabbits, deer, as well as one specifically for cats and dogs. Though the products are not YET available in Canada, they are freely available in the U.S. I suggest, if you wish, that you call them toll-free at 1-888-92FENCE, or e-mail them at and ask them for the location of a dealer/store in Buffalo, New York. For those in other areas, Liquid Fence can supply the name of a dealer in the closest U.S. city.

“There is another way of accomplishing this, using electronics. The 1st and Foremost of Arizona company of-fers an ultrasonic device (cost about $80 US) which comes with a guarantee that you may return it and have its cost refunded if you find it doesn’t work within 30 to 60 days. This retailer may be reached, toll-free, at 1-877-820-0570, or by e-mail at: They do ship to Canada, with fees averaging about $20, and recently they are seeing lengthier delays with customs clearance, but the shipments do eventually ar-rive. By the way, they do not refund shipping fees on returns but get very few of them.”

Finally, Henry and Rita Hymans, also of Vancouver Island wrote with what just could be a major problem: “Most of our rhodo's are all getting brown tips on the green parts, which turn completely brown, crispy, and then fall off. Even some of the buds are dried up, and I have not discovered any bugs so far. We have even fertilized them regularly, can you tell us, how much fertilizer do you give to 3-4 yr. old plants? Hope you can shed some light, on what's wrong with our plants, we love them so very much for they lush colors, and their beauty???”

I find it difficult to make a diagnosis on this particular problem, without seeing some examples of the brown tips. Currently, there is a lot of ‘hype’ about Sudden Oak Disease, which can attack a large variety of trees and shrubs including rhododendrons. It is generally recognized on rhododendrons by large, irregular darkened brown spots on the upper surface of leaves, and lighter brown spots on the underside. Again, not knowing the Hymans’ city/town I am unable to recommend a location where they might get this problem identified. If they are anywhere near Victoria, they might consider a visit to Norman Todd, owner of Firbark Nursery, located just off the Pat Bay Highway, immediately behind Elk Lake Nursery.

Regarding the fertilizer, there are special Azalea/Rhododendron fertilizers available that should be applied immediately that the plants have finished flowering (or should have!).

Finally this week, I have included a photo of my old Silent Yardman lawn mower. It is in quite good shape (the paint is a bit rusty, but that’s all). I need the right-hand-side rubber roller support, which looks essentially the same as the one from the left-hand-side in the last photo. If you happen to know of someone with either the part, or the mower, do drop me a note at And, thanks!

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