Phenology & Gardening

Jan 20th


Even if you don’t know what the word phenology means, I can pretty much guarantee you already have experience with it. Phenology is basically the seasonal rhythms of growth, maturing and death in the plant and animal world and how these life stages correlate with environmental factors, such precipitation, temperature and other climatological forces.

The Google definition defines phenology as “the study of cyclic and seasonal natural phenomena, especially in relation to climate and plant and animal life”.

A good example is the annual blooming of the cherry blossoms in Japan. Each year the cherry trees almost simultaneously explode with blooms of creamy white and soft pink that last only a few weeks. The exact date when the trees bloom though is not set. Instead, the trees respond to abiotic factors, such as the increasing sunlight, temperature and moisture to determine when they will bloom. Studying these patterns – cause and effect – is phenology.

Ok, what does that have to do with gardening?

Quite a bit! Here in the Pacific Northwest I watch for clues that spring is on its way or when the danger of frost has passed. This winter has been particularly mild here in Seattle and currently red alder (Alnus rubra) is already blooming with bright, lime-green catkins dangling from the tips of tree branches. Indian plum (Oemleria cerasiformis) is also coming to life, with green leaf buds forming on its branches. Indian plum is one of the very first plants to break winter hibernation and is an important food source for birds and animals during a time when few other plants offer forage. Monitoring these patterns and cycles allows me to glean clues about this year’s weather and growth patterns and therefore help determine when I should set seed or transplant delicate starts into the garden.

The most interesting part of phenology is that very often it’s unique to your microclimate. While Indian plum may be budding here, just a mile away it could already be flowering. It depends on the environmental factors unique to each specific site. One way to track these changes is to start a journal or add notes to your existing garden journal. Noting key indicators, like when big leaf maple (Acer macrophyllum) is flowering or when its seeds (those child hood favorite helicopters) start dropping, as well as the temperature and weather pattern (rain, sunny, partly cloudy) creates a valuable record that over the years will help you “read” nature.

If you’re interested in learning more about the science of phenology, consider a google search or picking up a book on the topic. A favorite website of mine is the USA National Phenology Network. They also have a program called “nature’s notebook” where citizen scientist can contribute data towards a collective pool that helps both research scientists and gardeners alike track patterns.