UNITED STATES—Contrary to popular belief, good autumn foliar color, or ‘fall color’, is possible on the West Coast. Mild weather only limits the options for trees, shrubs, vines and perennials that color well. Besides, autumn foliar color simply is not a popular priority in western gardening.
Boston ivy must be the best climbing vine for color in autumn. Unfortunately, it is too aggressive for refined urban gardens, and clings with ‘holdfast discs’ that damage the surfaces that it climbs. It is better for freeway soundwalls and interchanges. Grapevine is a more docile option, and also produces grapes, but most cultivars (cultivated varieties) are not too remarkably colorful. Wisteria can turn an appealing shade of soft yellow where well exposed, but its best asset is still the colorful and fragrant bloom in spring.
Eastern redbud, crape myrtle, smoke tree and currant are some of the better shrubbery for autumn foliar color. Of these, Eastern redbud develops the most subdued shade of yellow; and crape myrtle develops the most brilliant shades of yellow, orange and red. Both are incidentally considered to be small trees. Smoke trees that have purplish foliage in summer are typically less colorful in autumn than those with green summer foliage. Some of the Japanese maple trees that display good color in autumn are smaller than some of the larger shrubbery.
The North American and European maples that are so colorful where autumn weather is cooler are not so impressive here. Even if the color is good, the foliage does not linger very long, but instead falls as soon as the weather gets breezy or rainy. Silver maple and box elder (which is actually a maple) which are so pretty and green through summer can actually look rather dingy as they yellow for autumn. Fruitless mulberry, tulip tree, black walnut and the various poplars and locusts can color well if the weather is just so, but display only bright yellow without orange or red. Maidenhair tree impresses with the same limited color range only because it is so reliable, and the yellow color is so very brilliant.
Really, the best trees for autumn foliar color are still sweetgum, Chinese pistache and flowering pear. They do not need much cool weather to display impressively brilliant blends of yellow, orange and red.
Highlight: Maidenhair Tree
There are not many trees that are as reliable for strikingly bright and clear yellow autumn foliar color as the maidenhair tree, Gingko biloba, is, even in mild coastal climates. The distinctive leaves flare out like fish tails, each with a prominent cleft that divides it into two wide lobes. (The species name ‘biloba’ means ‘two lobed’.) Some cultivars lack foliar clefts, have narrower leaves, or even develop milder yellow color in autumn. Those developed for home gardens exhibit relatively symmetrical branch structure, and are exclusively male, so can not produce the stinky fruit that some older female trees drop. (Trees grown from seed can be either male or female. Female cultivars are grown for fruit production and bonsai.) Some ancient trees in Japan, Korea and China are more than a hundred feet tall. Fortunately, maidenhair tree grows slowly enough to stay proportionate to compact urban gardens for many decades.
By Tony Tomeo