Thursday, December 15, 2011

Giving Plants the Cold Shoulder

Herbaceous peony
It came as a shock to me when I first began gardening that not everyone can grow tulips and peonies. If you live in the south, most spring bulbs that we in the north take for granted, like tulips, daffodils, crocuses and such, just won't make it down there. But of course, they have things that we can't grow in the ground year round either.

The problem with trying to grow tulips in the warmer climates is that these bulbs and plants need a period of cold weather - typically below 45°F - in order to flower. This is called vernalization. Bulbs can be pre-chilled and then planted, but southerners may not want to be bothered, just as many northerners may not want to dig up tender bulbs/corms/tubers in the fall, such as dahlias and gladiolus.

Cold temperatures also affect warm climate plants in a similar way when it comes to producing blooms. Several years ago, I purchased some Amazon lily (Eucharis grandiflora) bulbs while on a visit to Florida. I was taken by their beautiful white blooms and large, shiny green leaves. I brought them home, potted them up, and they grew wonderfully. But they didn't bloom.

Amazon Lily
Eucharis grandiflora

The lush green foliage of my Amazon lilies made for a beautiful house plant, but I longed for those gorgeous flowers. Why wouldn't my plants bloom? Quite by accident, I discovered that this is one of several plants that need cooler night temperatures in order to produce flowers. One winter, I put the Amazon lily in a spare bedroom that we only heat to about 55-60°F. When spring came, I put the plant back in the living room and one day I walked in there and found several blooms had appeared!

Christmas Cactus
Schlumbergera x buckleyi
Other plants that require this cooling off period in order to bloom are Thanksgiving and Christmas cacti, which are also responsive to the shorter daylight hours. Some orchids can be spurred to bloom by keeping them cool for a period of time as well.

Sometimes it takes awhile for the lights to come on in my brain, but I had a thought a couple of weeks ago about this cool temperature thing. In all the years I've had jade plants, both common and variegated, I've never had a single one of them bloom. I didn't even realize that they were capable of producing beautiful flowers until I saw a large plant in full bloom last year at Planterra in Michigan.

Jade Plant
Crassula ovata
So what I'm going to do is put my jade plants in the cooler bedroom for the winter, then bring them out when spring gets here. No, that isn't exactly how things would be in their native environment, but plants can be fooled and coerced in many ways. This won't hurt them and maybe, just maybe, they'll pop out blooms.


commonweeder said...

My big jade plant bloom irregularly in my bedroom. Does that tell you anything about the way I like to sleep in a cold room?

Kylee Baumle said...

Pat ~ Oh this gives me hope! Thank you for telling me this! My husband likes sleeping in a cold room, too. I don't like it warm like the rest of the house, but he likes it a LOT colder than I do. I read once that your body temperature has to get down to a certain level or you won't have good quality sleep, so cooler nights are good for you!

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