91127thumb(alternate)Mild climates allow more flowers to bloom through autumn and winter here than in most other parts of America. That is why cool season annuals like pansies and violas are so popular. Cyclamen can be planted now too. None will be obscured by snow. By the time cool season annuals start to fade, warm season annuals will be replacing them. There is something to bloom in every season.

There are a few disadvantages to mild climates, though. Many plants rely on significant winter chill to stay on schedule. Inadequate chill limits the cultivars of apples and pears that are productive here. Not many spring bulbs will naturalize. Prior to winter, some deciduous plants are hesitant to resign to dormancy until they experience a chill that is cool enough to convince them it is autumn.

Some deciduous plants recognize a specific temperature as credible evidence of a change of seasons. Others want a specific temperature to be sustained for a specific duration or repeated for a few nights. Shorter days and longer nights are taken into consideration by species who want to confirm what they deduce from the weather. Different plants use different methods of observation.

That is why deciduous plants who develop foliar color before defoliating in autumn do so on their own terms. Weather conditions that promote excellent color among birches may not be the same that cause flowering cherries to color well. Warmth and minimal humidity that sometimes prompt premature and blandly colored defoliation of sycamores might enhance later color of sweetgums.

Sweetgum, Chinese pistache, flowering pear and ginkgo are the most reliable trees for foliar color in autumn. Ginkgo turns only brilliant yellow. The others exhibit an excellent mix of yellow, orange and red. Crape myrtle can be about as colorful, but is not always as reliable.

Of course, there is more to these and other deciduous trees than their colorful foliage in autumn. After all, they are trees. Their particular characteristics and appropriateness must be considered before adding any of them to a landscape.91127thumb

6 thoughts on “Autumn Weather Prompts Foliar Color

  1. The unpredictability of crepe myrtles was obvious here this fall. Last year, they turned beautiful oranges and yellows, and held their color for nearly two weeks. This year? Not so much. They began defoliating early, without a lick of color to their leaves, apart from a bit of mottling. Predicting autumn color’s as iffy as predicting any other weather phenomenon.

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    1. Ginkgos have that effect. I find them boring; but I know of a few who are not horticulturally oriented, but are fascinated by ginkgos. Chines pistache would not be my favorite either, but they happen to be one of the most reliable for color in mild climates. I prefer the North American maples and the Norway maple, but they do not color reliably, and when they do, they defoliate soon afterward.

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  2. Great article, thanks and love the subtle humour too. Your experience of the seasonal change in the fall is so very different from ours. Our trees held their leaves a little longer this fall I think and the colours were maybe not quite as nice as might have been expected. As you pointed out and I did not actually realize, or stop to think about, there are a lot of different factors at work.

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    1. We might notice the different factors more here because foliar color is not as reliable in our mild climate. There are only a few trees that excel at. Others have good seasons and bad seasons.

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