There is something about this time of the year, when we leave behind the shortest day of the year, that energizes me as a gardener. With each day, the additional minutes of day length trigger me to think about the coming of the next season. Just like some plant, day length seems to enter my soul and bring me forward.
It always seems fitting that some plants, and several that we associate with the holidays, are impacted by day length; in fact, it is critical to their bringing themselves into flower. Two in particular, the Christmas cactus and the poinsettia, require long nights with no sun exposure to trigger their reproductive cycle. For those who have grown Christmas cactus and then not had them rebloom in the coming years, it is essential to understand that these plants require a series of long nights of complete darkness—more than 12 hours each night —in order to form the buds of the flowers that we have come to love.
This mechanism is how the plants determine that the season is ideal to go into their reproductive state. Any exposure to light, even the artificial light of a lamp during the night during this time, will cause them not to flower. Some people simply manage this by covering them with a box at night during this season, others simply put them in a room that is not illuminated and closed off to push them into bud. Once they have formed buds, they are on their way to providing their wonderful cascading flowers, often in time for the holiday for which they are commonly named.
Poinsettias are similar in their need for long nights in order to bloom and this can be a complicated thing for commercial growers of these holiday standards. A gardener who keeps one from year to year would need to simulate this process or protect them from being exposed to light during the night. Many of us, however, just treat poinsettias like annuals, as they are not particularly interesting once their colorful bracts go by.
Hopefully, these plants teach us to pay attention to their needs and how they respond to the conditions around them and also teach us a bit about how the cycles of the season impact us.
Two other holiday plants, amaryllis and cyclamen, teach us other ways that our environment impacts us. Holiday cyclamen tend to like cool temperatures and are best kept on a cool windowsill to give them the temperatures they prefer—they are the equivalent of the holiday guest who always thinks the house it too warm and are best set in a corner where they can cool down.
In the case of amaryllis, on the other hand, it is warmth that triggers them to extend their long scapes and flowers, and they can be held back or pushed forward by managing their temperature. A warmer location will push them forward, a cooler one will hold them back, and just like a sun worshiper who rotates to get an even tan, their stems can be kept upright by rotating them so that when they reach for the sun, they are still upright.
Just like holiday guests, these winter bloomers are best when their needs are met.
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A gardener grows through observation, experimentation, and learning from the failures, triumphs, and hard work of oneself and others. In this sense, all gardeners are self-taught, while at the same time intrinsically connected to a tradition and a community that finds satisfaction through working the soil and sharing their experiences with one another. This column explores those relationships and how we learn about the world around us from plants and our fellow gardeners.
