By Kathy Conner Cornell
VCE Southside Master Gardener
From a couple of conversations I’ve had lately, I feel some people have a misconception about what changing from standard to daylight saving time really means. One friend said she thought we should stay on daylight saving time so the days stayed longer. Another friend said she liked it when we went to daylight saving time because the days would be longer. Let me be perfectly clear, the time change does not have any impact of day length. That is solely based on the position of the earth in relationship to the sun.
This peach tree’s flowers are browning after the hard frost on the first day of spring.
Let me explain. Starting with the winter solstice, which happens around December 21 each year, the earth is farthest from the sun so we are in winter. During the winter solstice, the daylight hours are the shortest of the year. Plants react to both photoperiod, hours in the sun, and temperature. The long night short day period tells hellebores Helleborus and snowdrops Galanthus to bloom. Yes, there are treats of flowering plants even in the darkest period. After the winter solstice, the days start getting longer, not by much but by maybe 30 or 45 seconds at first and then moving up to a minute and a half. Checking with Weather Underground, today the length of daylight is 2 minutes and 22 seconds longer. The day length now is 11 hours and 57 minutes which is leading us right to the second phase.
During the spring equinox, around March 21, there is equal daylight and darkness. The earth’s axis is tilting closer to the sun. This photoperiod gives rise to spring bloomers such as azaleas, flowering plums and flowering dogwood. Daylight continues to get longer after this date. Leading us to the short night long day plants.
Long day plants include those that flower in late spring, early summer such as pinks Dianthus black-eyed susans Rudbeckia and bee balm Monarda. Around June 21 is the summer solstice with the longest daylight hours of the year. Days slowly get shorter after the solstice. Leading to the next phase – the Fall Equinox.
The equinox occurs around September 21. This phase stimulates fall bloomers such as windflower Anemone, asters Symphyotrichum and pineapple sage Salvia elegans to bloom. You may question why these plants didn’t respond to the spring equinox. Remember there are two things that plants respond to – day length and temperature. The warm temperatures were not there to signal to the plant that it is time to bloom. After the equinox, day length gets shorter and the cycle starts all over with the Winter Solstice.
Having said all that, some plants only paid attention to the temperature this year. After the hard frost this morning, flowering plants that made it through other lighter frosts most likely suffered damage this time. I feel we will see a shortage in the peach crop and possibly blueberries.
Some of you may remember that a bill was going through congress to keep daylight saving time year round. It passed the Senate but stalled in the house and is past the limit for passage. Another bill would need to be introduced for it to remain active. In a recent survey, 13% preferred standard time year-round, 44% of U.S. residents preferred daylight saving time all year round and 35% were okay continuing to clock switch twice a year. I guess I side with the latter group. Bottom line, day length depends on the position of the earth in relationship to the sun. It is a matter of having sunrise and sunset an hour later with daylight saving time.