FAll Color
By Val Whitmyre, U.C. Master Gardener
Pistachia chinensis
As the days grow shorter, leaves start to go into dormancy by decreasing their production of chlorophyll, the green pigment. Other pigments in the leaves then predominate and begin to show. If autumn is cold, we'll see more orange and red colors. If autumn is mild, we'll see more yellow. Early frost or severe droughts are the only deterrents to color change.
First on my list is the Chinese pistache ( Pistacia chinensis ). Because it adapts to most conditions and provides shade as well as magnificent fall color, the pistache is one of the most popular trees in the valley. Its only requisite is well-drained soil. Infrequent deep watering is best. It can take lawn watering as well as little to no summer water.
The mature tree has a graceful pyramidal shape with several two- to four-inch narrow leaves on each stem. Birds visit the inedible, tiny red fruit. A young tree may seem a bit lopsided, but with a little care, it becomes a 50-foot shade tree perfect for the patio, lawn or median strip. As it goes into dormancy, its leaves turn deep purple-red, bright red, orange and yellow.
Each tree has its own genetic color marker and retains the same color each year, so it is important to see them in the nursery as they are changing to choose the ones you want. Viewed at sunset, the pistache glows, reason enough to have one. You can see a magnificent display of this tree lining the streets of Yountville and portions of North Jefferson Street in Napa.
The tupelo tree ( Nyssa sylvatica ) has two other names: sour gum and pepperidge. It grows slowly to about 50 feet with a 25-foot spread. Its tiny black fruit attracts birds. An easy tree to grow, it tolerates poor drainage and isnÃt fussy about soil. Seeking cool shade, my Lab, Joe, dug a few pits under my tupelo tree with no stress to the tree. In fall, the shiny green leaves turn a spectacular orange-red. This is one of the best trees for fall color. You can see this tree in the ground at Van Winden's Nursery in Napa, near the main building.
The Ginkgo biloba , or maidenhair tree, is an ancient tree. Its leaves have been found in fossils. It is the only species of the Ginkgoaceae family. For vibrant yellow fall color, this tree is a must. Well behaved and both pest-and disease- resistant, the gingko slowly grows from a conical shape to a spreading 50-foot tree.
It is important to know whether a gingko is male or female. The female ginkgo bears messy, foul-smelling fruit. All cultivars (named varieties) are male plants. The "Autumn Gold" variety is a good one. The leaves are semi-divided two-inch fans that remind me of golden butterflies.
The Japanese maple ( Acer palmatum ) is a favorite with many gardeners. With its graceful form and lovely fall colors, it adapts beautifully to dappled light, but leaves tend to suffer from sunburn if placed in direct sun. Red-leaved maples seem to be more susceptible than the green-leafed varieties.
This delicate-looking tree withstands our rainy winters and hot summers but needs good drainage and protection from wind. I recently saw a bonsai forest of Acer atropurpureum , a fancy name for the red Japanese maple. Nine tiny trees were all displaying glowing rosy-red leaves.
It's said that everyone likes Japanese maples, and rightly so. The branches grow in arching planes up to 20 feet. They do well as a container plant, as an under-story tree, in groups or in lawns. This tree is resistant to oak root fungus and appreciates an occasional deep watering to flush salts from the soil. Give it the same treatment as azaleas or ferns, and it will reward you with beauty in each season.
It is well worth the time to take your camera on a Sunday drive when these and many other species are in their full fall glory.