Documents: Hot Horticulture Issues:

Moss & Bougainvillea

What to do about moss in lawns--several approaches; the availability (or non-availability) of sundews; and growing Bougainvillea!
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

February 5, 2006

Two shots of Bougainvillea, above a close-up I took on St. Lucia a few years ago, and below, three different cultivars growing in pots and for sale in a South African garden centre about 15 years ago. Author photos.

Back last November, Keith Rout of Royal Home Improvements e-mailed me with this question about moss on lawns: “On the lawn of a customer of ours there seems to be a moss ‘take-over-bid’ on part of their lawn. Some history: there used to be patio stones over the area that have been removed. We're not sure if they had sod put down or seeded the new lawn area a couple of years ago, but, just this last summer the moss has taken over the area. What do you think would be causing this moss build-up? If you need some more details let me know and I can ask our client.”

During one of our conversations on my AM740 radio programme in Toronto, Paul Napolitano, the president of Royal Home Improvements, discussed the problem, but subsequently, Keith e-mailed me again asking if he could have a summary of what I said since the homeowners had not heard the programme. So, a couple of months later, here is that summary.

Moss in lawns is not an unusual happening, in fact here in B.C. it is something we deal with regularly, though it doesn’t happen all that much in Ontario where the climate is not as damp. Moss in lawns has at least three causes: excessive dampness, a soil too acid and too much shade, and as well, almost always a soil that lacks fertility. You may have one, two or all three of these. Early in the spring I would apply a de-moss product that contains (preferably) Ferrous ammonium sulphate. About two weeks later you will likely need to spring-rake the dead moss out. This is not particularly a dangerous product to use (although you may find it difficult to obtain); it is basically a fast-acting fertilizer. Applied to wood or concrete it will stain so be sure to apply it just on the areas in the lawn where the moss is.

There other options as well. The fertilizer Ammonium sulphate (21-0-0) will work but it will brown the grass as well as the moss. However, the grass will recover in about three weeks. You may also use super-phosphate (0-20-0), at 3 kg/100 m2 (6 lb./1000 sq. ft). but if you use this method, you’ll definitely need to over-seed with a shade-loving grass seed (such as a mix containing predominately fescues), presuming that the area is at least partially shaded. Finally, bluestone (Copper sulphate) may also be used at a rate of 142 grams (5 oz.) in each 18 litres (four gallons) of water covering 100 m2 (1,000 sq. ft.).

Yet another option is a reasonably easily obtainable product from the Safer’s people (known for their insecticidal soaps); it is known as Safer’s De-Moss. This is a totally different approach, and I have found it to be much slower acting that the Ferrous ammonium sulphate we use here.

In addition to killing the moss you really should try to improve the pH of the soil; i.e. raise it. You do this by lim-ing the soil, following the label directions on whichever lime product you choose. I recommend only the Dolopril product and that is what we use here. Other types of lime, which may be less expensive, are ever so much slower working. Also, other lime products are twice the weight and have half the coverage, and perhaps worst, are extremely dusty. The lime should be put on when the grass is going to remain dry for two days or more (ideally), and it should be put on about a week before the spring lawn fertilizer.

Here is an unusual request from Cynthia McGovern, “Where can we buy sundews in Toronto? I've found pitcher plants and Venus fly traps but that's it, locally. Thanks for your insight.”

Well Cynthia, I did not realize how hard sundews (Drosera) are to come by. Unless you can call upon a favourite garden centre manager or florist shop to keep an eye out for some at the plant wholesalers (or the Mississauga clock) for you, then I think you may be pretty well limited to seeds. The closest supplier would appear to be Niagara Carnivores, but their web presence is rather small and contains no other point of contact (such as a telephone number) that I could find. Here is the Website: A second supplier is Gardens North, 5984 Third Line Road N. North Gower, ON K0A 2T0, 613-489-0065. That is just south of Ottawa. Here is the specific web page I found:

Still another source of seeds, believe it or not, are private sellers on e-Bay.

About two weeks ago, Patty Farmer of unknown location in Canada, wrote to Doktor Doom with the following question. Grigg, the Dok, forwarded it on to me: “Hello: Last spring we purchased a fairly large Bougainvillea that was in bloom. It spent the summer out of doors fairly successfully. When we brought it inside it sulked and dropped leaves just as we were led to believe that it would. Now, it has started to bloom again but looks kind of spindly and gangly. Is there a way that we can prune or tie it up to look a little more full and bushy? What are our next steps in its care? Any help would be useful. It presently lives in our solarium where it gets morning sun and really good light all day long. Thank you.”

It always helps if questioners supply their exact location in Canada, and sometimes it is absolutely necessary to know that information if a good answer is to be formulated. In this case, the other item that Patty has not supplied is information on how and when the plant was fertilized. So, here then would be my recommendations that worked well for us in Toronto. Keep the plant in a container, and keep the roots crowded in the pot (i.e. repot only when roots totally overgrow the pot, and then move up only one size). Fertilize well with a high phosphorus fertilizer, but a good balanced one such as BioTLC Liquid Growth’s Garden Growth Formula 6-12-6 about every two or three weeks during the entire growing season. That means, from what you say, you should start now. If you put it outdoors again this year, be sure to bring it in soon after Labour Day. Slow down on the watering and stop fertilizing at that time. It should not be totally dry in the winter, but it will need only small amounts of water. Bougainvillea are not fussy as to pruning, and eventually you will have to be fairly ruthless as growth will be abundant!

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