The Changing Lanes of the Sun

A Winter Sunrise (photograph courtesy Al Past, author of Distant Cousin and other novels)

A Winter Sunrise (photograph courtesy Al Past, author of Distant Cousin and other novels)

In South Texas, we get plenty of sunshine—more than enough, even in winter, to grow a lush and vibrant garden.  Ironically, insufficient sunlight can be a problem in many South Texas gardens.

The problem is not a lack of sun, but rather too much shade over the garden.   Thomas Jefferson said that “under the constant, beaming, almost vertical sun of Virginia,  shade is our Elysium.”  And Virginia has nothing compared to the burning heat of a South Texas summer sun.  We adore the shade, and a lawn without shade can be a miserable place.

However, trees, fences, houses and other structures around your vegetable garden can get in the way of the light.  And because of the changing lanes of the sun, a garden that gets enough light during the summer may be shaded out during the winter.

The Changing Path of Sun  Diagram Courtesy Solar Choice

The Changing Path of Sun
Diagram Courtesy Solar Choice

The sun, over the course of the year, travels through different paths in the sky.  On the spring equinox, in March, the sun rises exactly in the east, and sets exactly in the west, and the hours of day and night are equal. Then, through the summer, the sun moves a full 23.5 degrees north of its line at the equinox.  There are more hours of sunlight during the summer, and the sun shines at a more direct angle over the garden.

The sun then crosses back over the line of the equinox and moves another 23.5 degrees south for the winter solstice.

The Changing Angle of the Sun can Create More Shade During Winter if there are Trees and Structures on the South Side of the Garden (Diagram Courtesy DOE)

The Changing Angle of the Sun can Create More Shade During Winter if there are Trees and Structures on the South Side of the Garden (Diagram Courtesy DOE)

The winter solstice is today, Saturday, December 21st.  Today, we will have the fewest hours of daylight all year, and the sun will travel through its southern-most lane, its lowest angle in the sky.

The movement of the sun from the winter to the summer solstice represents a full 47 degrees of change each year.  You can measure this remarkable shift of sunlight by standing in your garden today and memorizing the exact points on the horizon where the sun rises and sets.  Then, do the same thing on the spring equinox and once again during the summer solstice.

Farming societies have been intimately familiar with these movements of the sun since ancient times, and it is interesting and helpful in modern times to know these angles of the sun.

A garden should receive at least eight hours of sunlight each day.  A few hours of direct sun at noon, and dappled shade in the morning and evening, is probably not enough light for good photosynthesis.

Insufficient sunlight leads to weak anemic plants that are highly susceptible to disease and insect damage.  Or, your plants, without enough sun, may slowly grow to full size, but produce very little fruit.  Adding fertilizer and pesticide will not help a garden that doesn’t get enough sun.

Today, the winter solstice, the shortest day of the year, is a great time to study the relationship between the light and your garden, to make sure you are getting the most from the winter sun.

(The following sunrises and sunsets were captured by Al Past, a linguistics professor, photographer, and author of the wonderful Distant Cousin novels.)

Sunrises and Sunsets Al Past 2 Sunrises and Sunsets Al Past 3 Sunrises and Sunsets Al Past 5 Sunrises and Sunsets Al Past 6 Sunrises and Sunsets Al Past 7

2 responses

  1. Beautiful photos. I suppose the one point of real connection between my work and that of the farmer is the light. Not only do days grow longer or shorter, the quality of the light changes from season to season – as you so well know.

    Even my little city balcony has to cope with those changing lanes of the sun. I face north, so in summer I have to protect plants from the afternoon scorching, and in winter everyone has to be scooted out to the opposite corner to get a little extra light.

    I haven’t worn a watch in 20 years. I tell time by the position of the sun in the sky – which works beautifully except for twice a year, when the bureaucrats have to go fiddling with our clocks and it takes me two weeks to adjust!

    • It is funny, but I never thought very much about the changing paths of the sun until I started farming. Sunlight, soil, and water are the main ingredients for what I do, so it pays to know about each of them. I taught a gardening class at my place, and we all stood in one of the gardens, and I showed exactly where the sun rises and sets on the winter solstice, the equinox, and the summer solstice. No one could believe how much the sun changed positions! It is such a huge swing, but it is so gradual, that we just don’t notice it. The garden we were standing in is a great summer garden, but a terrible winter garden, because of how the angle of sun changes and creates shade.

      Speaking of the quality of light, I saw an interview with Clint Eastwood where he said he filmed all of his Westerns in the fall. He said the quality of the light in the fall is uniquely rich, soft, and poignant. He said the autumn light added a certain richness, and even sadness, to his movies. What do you think about this? Do you seek out certain types of light in this way?

      Thank you so much for your interesting perspective! I am guessing your plants are all the way on the opposite corner of the porch today! Have a wonderful day, Justin

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