UF/IFAS Okeechobee County Extension Service

458 Highway 98 North

Okeechobee, FL 34972-2578

Phone: (863) 763-6469

E- mail:  dfculbert@ifas.ufl.edu

June 7, 2006

Feature Article - for release the week of June 11, 2006

Dan Culbert - Extension Horticulture Agent

 

 And It’s not Even Summer, Yet!

Based on recent heat and humidity, the feel of our weather is that summer is here.  But a look at the calendar shows that we are still “enjoying” spring time here in Florida – and that summer will not arrive until next Wednesday, June 21^st.

If you have been working in your landscape recently there are some less obvious changes in our seasonal conditions.  Here are two: our day length has been getting longer, and our shadows are getting shorter.  Today’s column outlines these changes and offers some ideas on how they can be used to help create a more Florida-friendly Yard. 

Longer Days are here again

Daily weather reports often briefly mention the time of sunrise and sunset.  Over the course of a year, the time of these events changes daily.   We adjust our clocks each spring and fall to take advantage of increasing daylight in spring, and accommodate for less daylight in the fall.

Here in Okeechobee, our maximum day length on the first day of summer is 13.92 hours.  If you travel to more northern areas, the daytime hours will be longer:  on June 21^st, Jacksonville FL has a 14.07 hour day, New York City will enjoy 15.05 hours of summer, and those in Nome Alaska will see the sun for 21.31 hours.  Going south will shorten the day length: residents of Panama City, Panama will have a relatively brief “long-day” at 12.42 hours.

On the opposite side of the year is the first day of winter, December 21^st.  Here in Okeechobee this shortest day is 10.25 hours long.   Compare that with Jacksonville’s 10.11 hors of sunshine, New York’s winter solstice of 9.15 hours, and pity the poor folks in Nome that see the sun for only 3.52 hours that day.  However, the folks in Panama City get 11.72 hours of daylight.

Plants respond to differing day lengths by changing their growth patterns.  Some plants have found it better to produce their flowers, fruit and seed in the summertime, and are called long-day plants.  Others take their cue from shortening days to reproduce, which is why many fall flowers are know as short-day plants. 

If you are selecting annuals for your Florida Yard, be sure to ask your nursery supplier if it is a short day or long day plant.  This will insure that it is adapted to the season.  And right now, the choices are for long –day plants in our location. 

Shorter shadows in Summer Yards

Another change in our seasonal lighting is the length of the shadows.  On the first day of summer, go to the north side of your yard during the noon hour, and notice where the shadow from your roof-line falls on the landscape.  Make a note right now on your calendar to do the same thing on the first day of winter:  that shadow line will move considerably to the north.

This difference in summer vs. winter shadow lines is due to the tilt of the earth.  Scientists call this angle of the sun in the horizon the azimuth.  And these angles should be considered when planning the locations of landscape beds or home vegetable gardens and can be used to locate shade trees to save on summer energy bills. 

Between the hours of 3 PM and 5 PM are the warmest parts of the day.  Shading the western side of the home with properly placed landscaping can cut down on energy costs.  Also make note of where your air conditioner compressor is located, and try to give it some shade to save some money.

Azimuth angles have been determined for our location at different time of the year.   Consider the west side of your house to have an azimuth angle of 90 degrees.   For the critical 3 PM time of day, sunshine will be streaming into your Okeechobee windows and sliding glass doors at an angle of 87 degrees on June 21, which is just a little below due west.  At 5 PM, the sun will have climbed beyond west to an azimuth of 99 degrees, or a west-Northwest direction. 

Compare these sun directions with the first days of fall, when the 3 PM azimuth is about 45 degrees, or southwest, and the 5 PM angle, which is 73 degrees, or west-Southwest.  The spring azimuth angles are likewise bent to the southwest side of the compass.

A University of Florida Extension bulletin is available for those interested in more details.  It takes into consideration the height of your home and possible shade trees, and can help suggest where to place landscape plants for maximum energy conservation.  One word of caution: be sure that the height of a tree and its placement near buildings will not become a roof hazard if another storm should visit our area.

In addition to energy conservation landscaping, make note of the shadow lines when choosing plants for your Florida Yard.  Don’t place plants that need direct sunlight in the northern shadows of your yard.  Many flowers and vegetables, if planted in the summer sun, may be in winter shade, and will not grow well on the north side of your landscape.

I’ve placed more information on our Okeechobee web page, http://okeechobee.ifas.ufl.edu.  If you need additional information on how the seasons affect sunlight in the landscape, please email us at okeechobee@ifas.ufl.edu or call us at 863-763-6469.  Local residents can stop by our office at 458 Hwy 98 North in Okeechobee, and visit our Okeechobee County Master Gardeners from 1 to 5 PM on Tuesday afternoons.

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Trade names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.  Florida Cooperative Extension Service / IFAS / University of Florida.  Larry A.  Arrington, Dean Last update: 06/07/2006 .  This page is maintained by Dan Culbert  

references

Gilman, Ed. Light Exposure. [Planting Trees in the Landscape website ]Gainesville: UF/IFAS Extension Service, 1/06. http://hort.ifas.ufl.edu/woody/planting/site/light.htm 

Meerow, A.W. and Black, R.J.  Enviroscaping to Conserve Energy: Determining Shade Patterns for South Florida [EES48] .  Gainesville: UF/IFAS Extension Service,    http://edis.ifas.ufl.edu/EH216   [Note: for Okeechobee residents, use either the Fort Myers or WPB tables.]

US Naval Observatory.  Sunrise/sunset table calculations for 2006.  http://aa.usno.navy.mil/cgi-bin/aa_rstablew.pl