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. Where the messy fruiting structures (maces) and aggressive roots are not likely to be a problem, sweetgum is a tall and elegant shade tree. Sweetgum trees innately hold their colorful foliage well, and some sheltered trees sometimes hold their foliage through most of winter. Chinese pistache is neither as messy nor as aggressive as sweetgum is, as it forms a broad and low canopy that is likely to need pruning for adequate clearance. It is becoming more popular as a street tree in many municipalities. Flowering pear is perhaps the most cooperative of the three if pruned to improve structural integrity while young, but stays smaller than the others. It is actually quite proportionate to smaller gardens of modern homes.