What’s that wet stuff coming from the sky? Hopefully by the time you’re reading this we will have gotten some much needed rainfall. I wanted to research the latest scientific papers on how climate change is impacting our gardens.

Plants have adapted over millennia to their growing conditions. The abrupt differences due to changing climate forces plant to migrate or go extinct. When temperatures increase plants bloom earlier creating the potential for timing mismatch between pollinators and plants.

Phenology – not to be confused with phrenology which claims that bumps on the head predict mental traits – is the study of key seasonal changes in flowering times, emergence of insects and migration of birds from year to year. When do they occur each year? Phenology is a real science that has many applications. In farming and gardening, phenology is used chiefly for planting times and pest control. Predictions for fire season are based on factors pertaining to weather as well as plant growth. Certain plants give a cue by blooming or leafing out that it’s time for certain activities such as sowing particular crops or insect emergence and pest control. Often the common denominator is the temperature.

Websites like USA National Phenology Network at http://www.usanpn.org/ offer lots of information on the subject. The US Global Change and Research Program released the first 14 indicators of climate change. Among these is the Start of Spring indicator on this website which reflects the accumulation of heat sufficient to initiate leafing and flowering in temperature sensitive plants. Your own observations via Nature’s Notebook will help contribute to this research.

How will this spring compare to normal? This site is regularly updated with data submitted by gardeners like you. Starting this year they are adding a new aspect of spring- the end of spring. They will forecast the activity of plants that bloom at the tail end of the season. This information will help us understand the length of the spring season in a particular year as well as whether a location that seas an early start to spring also see an early end.

Indicator plants are often used to look for a particular pest and manage it in its most vulnerable stages. They can also be used to time the planting of vegetables, apply fertilizer or prune. Here are some common garden plants and what they indicate:

When daffodils begin to bloom, sow peas.
When dandelions bloom, plant spinach, beets and carrots.
When lilac leaves are the size of a mouse’s ear, sow peas, lettuce and other cool-weather crops.
When lilacs are in full bloom, plant beans.
Once lilacs have faded, plants squash and cucumbers.
When apple trees shed their petals, sow corn.
When dogwoods are in full bloom, plant tomatoes, peppers and early corn.
When bearded iris are in bloom, plant peppers and eggplants.
When locust and spirea bloom, plant zinnia and marigolds.

When forsythia and crocus bloom, crabgrass is germinating. When this happens the soil temperature at a depth of 4 inches is 55 degrees. Treat with an organic pre-emergent.
When crocus bloom, prune roses and feed your lawn.
Mexican bean beetle larvae appear when foxglove flowers open.

Record your own observations. Another great site is National Sustainable Agriculture Information Service at http://attra.ncat.org. Sites like these can also help you design orchards for pollination and ripening sequence, design for bee forage plantings, design perennial flower beds and wildflower plantings as well as plantings to attract beneficial insects and enhance natural biological control. How cool is that?