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Agapanthus, Crinum & Eucomis

Questions about non-hardy bulbs such as Agapanthus, Eucomis and Crinum in Ontario; and about that terrible item on protecting container plants over the winter in last week’s Toronto Star!
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 22, 2006



Above, three shots of Crinum; growing in Vancouver’s VanDusen Gardens (top) and two shots at Victoria’s The Butchart Gardens. Below, Eucomis comosa flowering in my garden this summer, amongst Coreopsis tinctoria ‘Tiger Stripes’. Author photos.

Jean Lander wrote just over a week ago with these comments and questions: “I was interested to read your answer re crinum. I live in zone 5b (15km north of Cobourg) and have successfully kept agapanthus outside over the past two winters. I mulch it with about 12" of mulch. They flower mid September. I cut three blooms off today to enjoy inside as frost is called for tonight.

“Last year I planted some Eucomis outside and I was not too impressed with them so did not bother digging them up. Anyhow one came up this spring and has flowered very well. It had not been mulched and had virtually no snow cover last winter.

“I have crinum with which I must do something. They have just finished flowering. Last winter I over-wintered them inside and kept them going without going dormant. However, they sulked most of the summer and only started flowering late September. I am considering digging them up and putting them in a greenhouse outside until the leaves die off and then putting them in the cold room until February and potting them up to start growing. Next year I think I will keep them in a pot and keep them in the greenhouse until I see buds. Is this ok? I am also considering leaving a bulb outside, mulching it well and seeing what happens. Perhaps I will plant it deeper?”

It is most interesting Jean, that you had a Eucomis bulb over-winter in zone 5b; they are not supposed to even be hardy here (zone 8) without mulching! I planted one here this year but it has not been through a winter yet and we will likely not mulch it just to see how it fares this winter. I would suggest that you mulch the Eucomis bulb(s) this winter, much as you did the Agapanthus.

As for your Crinum, I would experiment with a couple of methods. They certainly may be grown in pots, but since the bulbs are so huge, nothing smaller than 40 cm (15”) in diameter is recommended. You may be able to crowd several such bulbs into large container. Only when the foliage starts dieing down, or turning yellow should you cut it off, and then keep the container where it will not freeze. You certainly should try one outside, but I would not plant it much deeper than the usual recommendation of just a few centimeters of soil on top of the bulb’s tip. The mulching will be important.

For those who garden in containers and may have seen an article by Christina da Silva (who describes herself as a garden writer and designer) in last Saturday’s Toronto Star, please disregard most of the information she provided! I wrote the first edition of Gardening Off The Ground back in 1976 and from about two or three years before that even up to the present, I have been encountering perhaps more false information on the topic of growing hardy plants in containers than any other aspect of gardening. It is hard to choose which statements of Ms da Silva’s to cite as the most glaring errors! Try this: “Round pots, because of their shape, are harder to insulate with Styrofoam. The best compromise is to use Arbotex, with a waterproof inner lining of plastic."

I found no difficulty insulating round containers with Styrofoam, if my directions (of using old loose Styrofoam meat trays from supermarkets) are followed. And, to say that the best compromise is to use Arbotex, is ridiculous. Arbotex--a very good Canadian-developed and -made product--is good for wrapping the foliage of tender shrubs but will have no effect if used in or on a container!

Or, how about this gem, “For an established planting, it may be impractical to insulate the inside of the pot, so insulate the outside with bubble wrap (available at stores like Office Depot or at post offices) or burlap…”

If indeed you are going to rely on bubble wrap (and I would not suggest it), then you would need several layers of the material around the pot.

The other statement which should alert her readers to the possible fallibility of everything else in the article is: “As moist soil freezes slower, water the pots well…” The comparison she is apparently making here is moist soil vs. dry soil, and anyone who has gardened at all knows that soil that remains moist freezes faster in the fall and thaws later in the spring than dry soil.

Finally, having worked in a small way on the original (1967) Canadian Plant Hardiness Zone Map, I have to in-clude this sentence from Christina da Silva’s article: “Keep in mind that cold hardiness ratings of plants are based on foliage hardiness, not root hardiness.”

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