I have several varieties of japanese maples growing in Zone 9b. I realize the area is not great for growing maples but I have had success in keeping most the trees thriving (some do look pretty beat up by the end of the long summers). However, the trees do not show fall color. The leaves tend to simply dry up rather than change color. This is consistent amongst the 7 varieties I have. Any help would be appreciated.
I notice this will happened to me every year when I was living in Los Angeles. I think it's because the weather does not get cooler but the leaves are just following the shortening of the sunlight hours. Now I am living in Portland, Oregon and all my maples are showing colors. That's what I think though... Oh and also when they are new or have been relocated within the past three months I notice at they don't change much either other than turning brown and dropping.
Imperfect Ending, that makes perfect sense to me. Because in my area, I have found that warm and wet fall seasons produce a boring fall with hints of dull color quickly going brown. Whereas, when the fall is dry and sunny, with crisp cool nights, the colors explode with very vivid bright colors and a long lasting show. It will be interesting to see what others say that live in warmer climates.
I agree with all of you, weather and location sunny/shady has everything to do with it. hate to say it but LA and the environs are not the perfect JM growing area(s). just to add to JT1's fine post a couple of nights of hard frost will also brown out the exposed tops and ends of branchlets of JM's planted in more open spots..... E ~
Pack the trees in ice...ha ha ha.. or buy a snow machine and run it overnight during the fall season. :-)
Hi, Southern California doesn't get cool enough for JMs to show good fall colors unless you live in a cooler climate like the mountains. Layne
I disagree with what has been said. The Osaka/Kyoto area in Japan is at the same latitude as Southern California (i. e.: same length of daylight) and they are also zone 9 (http://www.jelitto.com/english/japan.htm), and in the Osaka/Kyoto area Japanese maples color beautifully. The most important difference between the Osaka/Kyoto area and Southern California is rainfall. Southern California has a Mediterranean type of climate with a basically rainless summer whereas in the Osaka/Kyoto area heavily watered throughout the summer and fall (6-7 inches/month on average). This is confirmed with my experience. I live in Southern France (zone 8) with a climate which is transitional from wet oceanic to Mediterranean. Sometimes we endure a Mediterranean summer with very little rainfall in September/October (that was the case in 2010 with less than 1/2 inch) and sometimes we get good rainfall in October (like in 2012, 2 inches). When the soil is dry the maple leaves turn brown almost without coloring at all whereas when we have had good rainfall in October the color display is outstanding and long lived. This year the display has been breathtaking. Therefore, I am convinced that the most important factor for good Fall colors in Japanese maples is abundant rainfall in the month prior to color change Gomero
I think that's interesting Gomero, comparing Loma Linda, CA to Kyoto Japan. I agree that rainfall can play a role in color. But I feel strongly that temperature plays even a bigger role. I like to remind myself that not all zone 9's and latitudes are created equally. If we look at the historic climate data for both areas we see a big difference in temperature and rainfall in late October into November (Kyoto advertises this as their peak fall season) In regards to temperature, when we compare the two graphs we see a very large spread between daytime highs and overnight lows for Loma Linda, California; whereas the high/low spread for Kyoto is much narrower. (see attachment) When we look at the fall time period on the graph, we notice the decrease in temperature for Kyoto is at a steeper rate than Loma Linda, CA. Average rainfall drops in the month of Oct in Kyoto, hitting its lowest point in the beginning of Nov. (see attachment) Comparing the temperature for the two areas between Oct. 1st to Nov 7th: Kyoto, Japan- -------------------Max / Avg / Min Max Temperature 82 °F 72 °F 60 °F Mean Temperature 74 °F 64 °F 52 °F Min Temperature 69 °F 56 °F 42 °F Loma Linda, CA ------------------Max / Avg / Min Max Temperature 104 °F 82 °F 62 °F Mean Temperature 83 °F 68 °F 58 °F Min Temperature 64 °F 54 °F 37 °F Another noticeable difference between the two areas is the humidity. Loma Linda averages 45% for Oct where Kyoto averages 66%. Weather data from wunderground.com An interesting article on fall color: http://www.usna.usda.gov/PhotoGallery/FallFoliage/ScienceFallColor.html "While temperature may dictate the color and its intensity, it is only one of many environmental factors that play a part in painting deciduous woodlands in glorious fall colors. Temperature, sunlight, and soil moisture greatly influence the quality of the fall foliage display. Abundant sunlight and low temperatures after the time the abscission layer forms cause the chlorophyll to be destroyed more rapidly. Cool temperatures, particularly at night, combined with abundant sunlight, promote the formation of more anthocyanins. Freezing conditions destroy the machinery responsible for manufacturing anthocyanins, so early frost means an early end to colorful foliage. Drought stress during the growing season can sometimes trigger the early formation of the abscission layer, and leaves may drop before they have a chance to develop fall coloration. A growing season with ample moisture that is followed by a rather dry, cool, sunny autumn that is marked by warm days and cool but frostless nights provides the best weather conditions for development of the brightest fall colors. Lack of wind and rain in the autumn prolongs the display; wind or heavy rain may cause the leaves to be lost before they develop their full color potential. " In areas that are often cloudy for much of the autumn, with rather warm temperatures, fall colors are dull at best.
Fully agree, that's exactly what I said. Unfortunately in Mediterranean climates (like SouthCal) 'ample moisture' in the summer is a dream and we are saved by the October rains if they arrive. All species are genetically programmed to start the process of forming the abscission layer in response to external triggers. The two most important being temperature and duration of daylight but the relative importance of each one varies from species to species. Some species respond mainly to temperature and those are the ones we notice having a different time for coloring from one year to another. Other species (like Virginia creeper) respond mainly to length of day and they behave like a clock, changing colors always at the same date irrespective of the temperature. Most species respond to both with variable influence of one or the other. There are other factors, like drought stress, that may have a strong effect triggering an early abscission. Gomero P.S.: The best colors in Kyoto are normally found in the second half of November.
Okay, I must have misunderstood you when you said: Because I thought that was very different from: But I am glad we are now on the same page. Thanks for the tip on when to go and see the colors of Kyoto. My wife and I would like to visit Kyoto in the future.
I don't think the issue for the OP is which conditions produce the best fall colours, rather which conditions cause a complete lack of fall colours in a SoCal or Med type climate. Both Gomero and the article quoted by JT1 have pointed to drought stress as the most likely factor. Low humidity and large swings in day/night temperature will obviously increase that stress. (From the article quoted by JT1: http://www.usna.usda.gov/PhotoGallery/FallFoliage/ScienceFallColor.html) Where I live it is the complete opposite, and the fall colour is most likely to be curtailed if it is too wet or too windy, but at least I would see some colour before everything was lost.
As I mentioned in my post, the large temperature swings and the difference in relative humidity between the two cities, I agree that lack of moisture and drought stress can play a role. But when SouthernCaliforniaMaple said "I have several varieties of japanese maples growing in Zone 9b. I realize the area is not great for growing maples but I have had success in keeping most the trees thriving (some do look pretty beat up by the end of the long summers). However, the trees do not show fall color." I figured they were giving the trees ample moisture during the growing season and that their question was towards the thriving trees, because the beat up ones were already a lost cause for looking good in fall. Ive reached the point that I can no longer continue to beat a dead horse. I am moving on to the next post..
Yes, stress can cause some Maples to attain better Fall colors in some areas (cool) but stress alone will not enhance Fall colors in some areas as well (warm). Temperature and light will better determine whether we see consistent Fall colors or not. Has little to do with abundant rainfall. Even in areas with little rainfall like us around here we can still achieve some decent to good Fall colors. If we study the East Coast or even Yosemite for that matter we can learn why the Sugar Maples turn their brilliant colors and the Quaking Aspen in Yosemite almost always turn their brilliant golden colors with the onset of shorter day length light and cooling from day to night - nighttime cooling as I've stated in the past. The Los Angeles basin, even Los Angeles area inland coastal areas do not have the nighttime cooling to allow these plants to achieve good Fall color. When the day temperatures are in the 70's and 80's and the nighttime low temps are in the mid 60's there is not going to be good Fall color production. Yet, Santa Barbara and neighboring areas, including Lompoc and Santa Ynez can yield pockets of areas that can produce good Fall colors as seen on other trees and Maples as well. What happens is in some of those microclimates we may have day temperatures in the 80's but can have some nighttime temps in the 40's. That is enough to allow these plants to color up. If any of you grew plants in a greenhouse you would know that once we cut back the amount of light followed by cooling, even to the point of running an air conditioner, if need be, that we can greatly enhance our Maples to color up well. I am surprised so few people have ever taken into consideration what some Oregon growers take for granted in that if we overwinter these plants in a cool greenhouse we not only can enhance Fall colors but can enhance Spring colors as well. Coolness and long day - short day manipulation can better determine if and when we will see Fall colors. The problem we have here is that during November we can have high temperatures in the 80's with low temperatures in the 50's, so our Fall coloring is sporadic at best, depending on the cultivar. If we can drop into the 40's we would have good Fall color on many of our Maples every year with the onset of shorter daylight hours in a day. Read up on long day - short day plants and how phytochrome comes into play in enabling plants to chemically fulfill their needs to yield better and more sustained Fall colors. Why are shorter days with light manipulation and greenhouse cooling so important to a Poinsettia greenhouse grower for the Holidays? Jim
It would seem that Japanese maples behave differently in Southern California than in Southern France. California vs. French cuisine perhaps? Gomero
Jim, thank you for sharing your insight on the topic. I often wondered if growers use temperature and length of light to enhance plants. I find it very interesting. I live in a micro climate influenced by Lake Erie. I have very much been aware of the influence of the lake by protecting my collection from frost in the spring and fall, along with extending our growing season. The lake also helps us from dipping into the negative temperature extremes over winter. This insight you provided with the example of growers using cold to influence spring colors, helps me realize another benefit to the micro-climate. My spring colors have always been much better than my parent's Japanese maples located an hour south. I always tried to understand why, but could not figure it out. Well, our spring starts later, because of the cold lake water and our daytime highs stay about 10-15 degrees colder in the spring. By summer the temperature spread narrows as the lake warms. So this difference in temperature maybe the reason for my intense spring colors that last much longer.
