Daylily Spring Sickness
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Plants, animals and insects are influenced by their environment, and time certain events in their life cycles in relation to the weather and climatic conditions. The study of this is called phenology. Phenological indicator plants are markers of the seasons, and people often use them to predict when certain events, such as a particular insect hatch, are likely to occur. Thus the blooming or leafing out of a specific plant may be used as a signal that it is time to apply control measures against an anticipated pest.

The use of indicator plants is often more accurate for this purpose than timing events by a calendar since the plants and insects inhabiting a particular area will have been exposed to similar conditions and adjusted their life cycles accordingly. We have all observed how a plant may vary somewhat in its bloom time from year to year and locality to locality depending on weather conditions and microclimates.

To find out if the onset of spring sickness can be predicted by the blooming of other plants, members of the task force are making notes of what is in bloom when the first signs of spring sickness appear in their gardens. The results for 2000 are listed below.

Each entry in the table represents one garden, and gives the date spring sickness first appeared, the climate zone, the location and the status of indicator plants.

Dates of Spring Sickness Onset - 2000

Date Zone of Garden State or Province Indicator Plants
March 23 Zone 5 Ohio Forsythia and daffodils
March 28 zone 5/6 Ohio Early daffodils in full bloom, Forsythia full bloom, 'Royal Star' magnolia full bloom, Rhododendron 'Cornell Pink', Anemone blanda in full bloom, Pulmonarias blooming, H. fulva ("ditch lily") plants along the roadsides around here are up from 4-8".
March 29 Zone 6 Massachusetts Early (not extra early) daffodils beginning to open, forsythia is not yet open.
n/a Zone 5a Vermont Red Emperor tulips in full bloom, first dafs have faded, white Dicentra eximia is about to bloom, first pink flowers of rock cress are open in the field gardens, buds rising on the wild columbines.
April 25 Zone 8 British Columbia Ornamental cherry 'Kwansan' has just begun to bloom.
May 1 Zone 4 Ontario Forsythia in full bloom, pulsatilla just starting, and pulmonaria in mid to late bloom.
May 1 Zone 3 Alberta Nanking cherry is just starting to bloom.
May 7 Zone 4 Wisconsin The daffodils are done here, tulips are at peak, lilacs are just starting to bloom heavily and the crab apples are spectacular.
May 15 Zone 5 Maine The forsythia is in bloom as is PJM rhododendron, Saucer magnolia, stelleta magnolia, early white azalea, tulips, daffodils, white violets, wild "Johnny jump ups"
May 16 Zone 5/6 Prince Edward Island Forsythias in full bloom, daffodils starting
May 17 Zone 4 Ontario Forsythia are done, the daffodils are winding down.
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This page last updated February 18th 2002
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