Gardens Galore: Day Length ~ By Karen Brewka

Nothing about winter gets me as much as the short days. Hibernation is looking better all the time! One of the good things about short days is my Thanksgiving Cactus. Well, really, it's a 'between Canadian and American Thanksgiving' Cactus. It's filled with blooms and more buds are coming. (The Christmas Cactus has rounded lobes on the leaves and the Thanksgiv-ing Cactus has pointy lobes.) Christmas and Thanksgiving Cacti set flowers based on day length. These and many other plants are sensitive to day length and flower according to a set photo period.
If I lived in Yellowknife, my plant would probably be a true Canadian Thanksgiving Cactus. But I wouldn't notice because I would be hibernating.
Chris Curray (2011) in The Simple Gardener, Inc. explains photo-periodism very well. “What causes the differences in the flowering time of these two species is a photo-periodic response. These plant initiate flowers in response to the shortening days of summer and fall and are termed short day plants. A short day plant with a critical photo-period of twelve hours will flower when the days are twelve hours or shorter.”
So the Thanksgiving Cactus started to respond around September 15th (twelve hours of day light) and began to form flower buds at the ends of the branches instead of more leaves. The flowers started to appear a couple of weeks ago. It looks like flowering will last for another couple of weeks.
Lots of flowers are day length sensitive and the forced flower industry has taken advantage of this to manipulate blooming time. That's how we get poinsettias and chrysanthemums blooming in time for Christmas sales. The growers use black cloth to cover the plants for twelve hours (or however long that particular plant needs to have a photo-periodic response) in order to get buds to initiate at just the right time The covering must be perfect – no light, not even moonlight – for as long as it takes for perfect flowering. If you ever get a chance to tour a production flower greenhouse before Christmas, take it. It is a beautiful sight. Acres of flowers all blooming at the same time!
The Valley Neighbours Garden Club has changed its meeting times. Now they meet on the second Thursday of each month at Valley Neighbours on Sunset Boulevard in Turner Valley. The club welcomes new members. For information call Bea at 403–933–7131. The Horticultural Club meets every second Tuesday of the month at 7:30pm. For information call Sheila at 403–931–3989.