Phenology – What happens when

Flowering Purple (or Red) Dead Nettle, with honeybee.Credit Kathryn Simmons

Flowering Purple (or Red) Dead Nettle, with honeybee.
Credit Kathryn Simmons

For ten years I have been keeping phenology records, as a guide to when to plant certain crops, and as a way of tracking how fast the season is progressing.

Phenology involves tracking when certain wild and cultivated flowers bloom, seedlings emerge, or various insects are first seen. These natural events can substitute for Growing Degree Day calculations. Certain natural phenomena are related to the accumulated warmth of the season (rather than, say, the day-length), and by paying attention to nature’s calendar you will be in sync with actual conditions, which can vary from year to year, and are changing over a longer time-scale..

Many people know to sow sweet corn when oak leaves are the size of a squirrel’s ear. By this point, regardless of date, the season has warmed enough to get oak leaves to that size, which happens to be warm enough for sweet corn seed to germinate and grow well. Some people transplant eggplant, melons and peppers when irises bloom; sow fall brassicas when catalpas and mockoranges bloom; and know to look for squash vine borers laying eggs for the two weeks after chicory flowers. Some transplant tomatoes when the lily of the valley is in full bloom, or the daylilies start to bloom.

Lilac is often used to indicate when conditions are suitable for various plantings:

  •   When lilac leaves first form, plant potatoes
  •  When lilac is in first leaf (expanded), plant carrots, beets, brassicas, spinach, lettuce
  • When lilac is in early bloom, watch out for crabgrass germinating
  • When lilac is in full bloom, plant beans, squash, corn. Grasshopper eggs hatch.
  • When lilac flowers fade, plant cucumbers.

Also, recording the dates of the same biological events each year can show longer term climate changes. In Europe, 500 years of recorded dates of grape harvests provide information about summer temperatures during that time. Project Budburst is a citizen science field campaign to log leafing and flowering of native species of trees and flowers across the US each year. Each participant observes one or more species of plant for the whole season.

 Here’s our Twin Oaks Phenology Record so far:

(c) Pam Dawling, 2013

Event 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Notes
Crocus blooming 26-Jan 25-Jan 6-Feb 10-Feb 28-Feb 17-Feb 30-Jan
Chickweed blooming 8-Feb 1-Jan 5-Mar 10-Feb 13-Mar 19-Feb 13-Feb 15-Feb
Robins arrive 27-Feb 31-Jan 20-Jan 26-Feb 2-Mar 14-Feb
Henbit blooming 14-Mar 7-Mar 12-Jan 6-Jan 7-Feb 20-Feb 22-Mar 2-Mar 15-Feb 15-Feb
Daffodils blooming 17-Mar 9-Mar 7-Mar 1-Mar 22-Feb 3-Mar 5-Mar 15-Mar 3-Mar 17-Feb Plant potatoes
Dead-nettle blooming 18-Mar 6-Mar 7-Mar 8-Mar 14-Mar 9-Feb 24-Feb 13-Mar 21-Jan 22-Feb 10-Feb
Spring Peepers first heard 4-Mar 11-Mar 10-Mar 3-Mar 3-Mar 6-Mar 11-Mar 28-Feb 23-Feb 5-Mar Plant peas
Overwinter Grasshoppers seen 26-Feb 4-Apr 25-Feb
Maples Blooming 10-Mar 6-Mar 15-Mar 12-Mar 28-Feb
Dandelion blooming 16-Mar 16-Mar 24-Jan 1-Jan 3-Mar 17-Mar 9-Mar 8-Mar 19-Mar Sow beets, carrots
Forsythia blooming 13-Mar 12-Mar 28-Mar 10-Mar 23-Mar 13-Mar 17-Mar 21-Mar 15-Mar 12-Mar 15-Mar Plant peas. Crabgrass germinates.
Peach blooming 15-Mar 25-Mar 26-Mar 25-Mar 13-Mar
Cabbage White Butterfly 25-Mar 20-Mar 7-Mar 8-Mar 11-Mar 6-Apr 24-Mar 12-Mar 14-Mar Dutch white clover blooms
Harlequin bugs 10-Apr 13-Mar 26-Mar 12-May 16-Apr 29-Apr 14-Mar
Johnny Jump-up blooming 16-Mar 30-Mar 14-Mar 20-Mar 3-Apr 17-Mar
Flowering Cherry blooming 27-Mar 4-Apr 3-Apr 1-Apr 6-Apr 25-Mar 17-Mar 18-Mar 20-Mar
Asparagus spears 6-Apr 4-Apr 4-Apr 5-Apr 6-Apr 6-Apr 21-Mar 19-Mar
Redbud blooming 5-Apr 13-Apr 9-Apr 3-Apr 2-Apr 7-Apr 9-Apr 7-Apr 4-Apr 19-Mar Expect flea beetles
Smartweed germinating 15-Apr 10-Apr 15-Apr 6-Apr 11-Apr 1-Apr 23-Mar 20-Mar <149 GDD base 48F
Lambsquarters germinating 20-Mar 20-Mar <150 GDD base 48F
Violets blooming 29-Mar 26-Mar 28-Mar 6-Apr 22-Mar 20-Mar
Morning Glory germinating 27-Apr 10-Apr 3-Apr 26-Apr 24-Apr 25-Apr 22-Mar >349 GDD base 48F
Tiger Swallowtail 19-Apr 29-Mar 15-Apr 16-Apr 18-Apr 10-Apr 28-Mar
Apples blooming 18-Apr 20-Apr 14-Apr 7-Apr 12-Apr 28-Mar
Dogwood (Amer.) full bloom 5-Apr 21-Apr 13-Apr 28-Mar Plant peppers; soil 65 F
Strawberries bloom 13-Apr 11-Apr 14-Apr 12-Apr 4-Apr 2-Apr 15-Apr 6-Apr 8-Apr 30-Mar
Lilac full bloom 16-Apr 20-Apr 21-Apr 22-Apr 19-Apr 21-Apr 14-Apr 18-Apr 1-Apr Plant beans, squash
Crimson Clover blooming 29-Apr 2-May 16-Apr 22-Apr 23-Apr 27-Apr 18-Apr 25-Apr 4-Apr
Whippoorwill first heard 1-May 22-Apr 15-Apr 24-Apr 17-Apr 25-Apr 8-Apr 14-Apr 5-Apr
Galinsoga germinating 1-May 22-Apr 16-Apr 20-Apr 6-Apr
White Oak “squirrel’s ear” 20-Apr 26-Apr 23-Apr 26-Apr 25-Apr 14-Apr 23-Apr 12-Apr Plant sweet corn
Tulip Poplar blooming 2-May 10-May 3-May 26-Apr 3-May 6-May 26-Apr 28-Apr 17-Apr Plant sw corn 200 GDD base 50F
Ragweed germinating 20-Apr 16-Apr 25-Apr 26-Apr 21-Apr Plant sw corn 200 GDD base 50F
Last Frost 24-Apr 4-May 3-May 1-May 8-May 17-Apr 19-May 10-May 14-Apr 25-Apr Average 4/30 (10 yrs)
Fireflies 7-May 2-May 1-May
Colorado Potato Beetle adult 22-May 3-May 7-May 29-Apr 27-Apr 3-May 25-Apr 2-May
Strawberries ripe 10-May 17-May 12-May 10-May 7-May 15-May 3-May 10-May 7-May
Purslane germinating 26-May 8-May 22-May 5-May 20-May 15-May 8-May
Baby Grasshoppers 12-Jul 30-Jun 26-Jun 17-Jun 16-May
Cicada first heard/seen 14-May 5-Jul 3-Jul 29-Jun 17-May
Hardneck garlic mature 14-Jun 19-Jun 13-Jun 5-Jun 4-Jun 30-May 9-Jun 11-Jun 6-Jun 31-May
Foxgloves bloom 6-Jun 11-Jun 8-Jun Bean beetle eggs hatch
Bean Beetle eggs 4-Jun 16-Jun 10-Jun 6-Jun 20-Jun Hatch when foxgloves bloom
Japanese Beetle first seen 16-Jun 21-Apr 15-Jun 20-Jun 29-Jun 21-Jun 850 GDD (base 50F)
“June” Bugs first seen 5-Jul 11-Jul 2-Jul 12-Aug 10-Jul 30-Jun 29-Jun 30-Jun 23-Jun
Corn Earworm first seen 28-Jul 8-Jul 12-Jul 10-Jul 14-Jul 150-490 (base 54F)
Fall Dead-nettle germinating 1-Sep 20-Aug 30-Aug 20-Aug 16-Aug 20-Aug 15-Aug 29-Aug 18-Aug Plant spinach
Fall Henbit germinating 28-Aug 20-Aug 29-Aug 18-Aug
Fall Chickweed germinating 7-Sep 7-Sep 5-Sep 6-Sep Plant spinach
First Fall Frost 3-Oct 6-Nov 27-Oct 13-Oct 29-Oct 20-Oct 19-Oct 23-Oct 30-Oct 22-Oct Average 10/22 (9 yrs)
Harmonia Ladybugs migrate east 18-Oct 12-Nov 21-Oct 27-Oct
Garlic planted (hardneck) 25-Oct 20-Oct 9-Nov 3-Nov 11-Nov 1-Nov 5-Nov 11-Nov 15-Nov 6-Nov Soil temp 50 F
Event 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Notes

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