Part 26 of a series by Eugene Howell
In the previous article we began the discussion of bonsai dormancy. We covered the definition and the fact that not all species go dormant, and not even each plant within a particular species, goes dormant at the same time. We also learned of the interest scientists have in the subject of dormancy. We finished the first part by asking the question, “So what causes dormancy and when can it typically be expected to occur?” We will answer that question in today’s article.
The first part of the question is easier to answer than is the latter part. Typically, dormancy is caused by one or more of the following four events; shorter days, cooler temperatures, hotter temperatures or drought. Two of these sound like an oxymoron, but they are not. Not all plants respond to the same events in initiating dormancy. Some plants need shorter daylight hours and/or lower temperatures while others need hotter/drier conditions. In both cases the plant is protecting itself from adverse weather conditions that might otherwise injure it. In the first case the plant is protecting itself from the cold temperatures that frequent winter, and in the second case the plant is protecting itself from the desiccating conditions that occur in late summer and early fall in some parts of the world.