Plant Phenology

            Plant Phenology is the study of periodicity (rhythmic phenomena) in plants as

 related to seasonal climactic changes. This includes time of budding, leafing, flowering,

 fruiting, as well as color changes such as fall color. It is also useful to know the time of color

 changes such as when certain purple leaved cultivars turn green in the summer, since many

 cultivars do not stay purple during the entire season.

            A general rule of thumb is that Spring advances about one week for every 100 miles of

 latitude. If you go 100 miles north, plants should be about one week behind in flowering.

            There is some correlation between plant phenology and insect, disease, and weed

 emergence. For example, lawn crabgrass pre emergent herbicides should be applied by the time

Forsythia flowers, since crabgrass seeds start to germinate at this time.

            See the Phenology Chart to view some phenology data. You can see that most Prunus or

 Cherries usually flower before Malus or Crabapples.

            See the Fall Phenology Data and Spring Phenology Data forms to use for recording plant

phenology information. Data is best if it is averaged over several years.