In defence of Purple Loosestrife (Lythrum salicaria)
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

June 25, 2017

Above, Purple Loosestrife growing well in a large flower bed of the Government of Saskatchewan in Regina. Note the large lettering at the top of the photo; and Loosestrife growing in a large mixed bed at Le Jardin botanique de Montréal. Below, Purple Loosestrife growing at Tommy Thompson Park (Leslie Street spit) in Toronto—shot is looking north towards Toronto’s Centre Island. And Gooseneck Loose-strife (Lysimachia clethroides) though considered invasive by some gardeners does not present the same problems as are alleged for Purple Loosestrife. Author photos.




Twenty-one years ago, almost exactly, I returned from a three week trip across Canada, from Osoyoos, British Columbia, to Pasadena, Newfoundland. We travelled by small plane, large plane, fast train, slow train, and car. I was head of a judging team for Communities in Bloom in its first year of operation, and while the trip was to judge competing municipalities in eight provinces, we also had a great opportunity to observe the country horticulturally in general.

In every province (except Newfoundland, where there is very little), purple loosestrife was at its best! Media reports have once again been condemning the plant, a common herbaceous garden perennial that it is claimed could well, in just a few more years, cause the demise of the few wet-lands that southern Ontario has left. The plant grows equally well in sun or part shade, but definitely prefers moist conditions. Its tall spikes of carmine-pink flowers are displayed from mid-June to late August, and its generally a very good perennial for garden use, particularly if you have a pond.

However, biologists and naturalists are calling for a government ban on the sale and propagation of the plant which they say, as a non-native, has no natural predators and is quickly taking over our already-too-few wetlands, and causing them to fill in.

I must point out that to call for an outright ban is not only a gigantic over-reaction, but also it simply will not work. It is decades ago now that the common barberry plant was banned because it was said to be an alternate host to wheat rust disease. That ban has been anything but effective! You can see common barberry growing wild and in abundance still, and, what about other similarly introduced non-native plants. Common tansy is in full yellow bloom now in many areas, and no one seems to be suggesting it be banned. Viper's bugloss or blue thistle was spectacular last year (a damp season) but is less so this year due to our drought-like conditions. Nevertheless, it is widely distributed and came from Europe, but there is no call for it to be banned, and it too prefers moist areas.

Purple loosestrife is a beautiful garden plant with a long blooming period, insect and disease resistance, and for most gardeners is safe to plant from a wetland point-of-view.

In response to continuing negative publicity, mostly from writers who just follow what others before them have written, I decided to do a little more investigation into the whole subject. I found that the possibility of purple loosestrife taking over other common wetland border plants such as cattails and natives such as willows is highly unlikely.

My late colleague H. Fred Dale had a farm pond edged with natives. He pointed out that naturally introduced purple loosestrife had been pushed right out by the native willows and cedars, and cattails.

Just what is behind the campaign to ban this beautiful, useful plant? It is a well-known fact that the Anglers & Hunters are the main organization pushing for a ban. These people don't like loosestrife around their fly-fishing ponds because they cannot fish from the edge due to its rapidly expanding growth. They would also, by the way, like to see cattails reduced to about 50 percent of their present numbers.

Will it in fact be responsible for the complete demise of all of our wetlands, as is promoted by the self-interest groups? Do you realize wetlands remain in existence for only a period of time--regardless of so-called predators such as loosestrife? Our individual existence is but a tiny fraction of the life of the planet. For us to say that wetlands are being destroyed entirely during our lifetime is rather self-serving. In fact, over the next 100 years, virtually all the wetlands we now know will cease to exist, and many new such lands will be formed. Observers of the natural progression of the planet's landform confirm this.

The real reason certain groups see purple loosestrife as a threat is that it threatens their sports--angling and hunting, and they have been successful in convincing other conservation groups that the plant is actually a threat to wetlands themselves. According to a past president of the Toronto Field Naturalists, the Ontario Federation of Naturalists have been receiving considerable funding from Ducks Unlimited and they have joined with the Anglers & Hunters in trying to have loosestrife banned.

One horticulturist acquaintance of mine has suggested that we form a new organization to oppose hunting--particularly the "pouring" of lead from shot into our rivers and lakes. Naturally, the symbol for this new organization would be purple loosestrife!

By the way there are other loosestrifes available and gardeners should certainly not hesitate to plant those.


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