UNITED STATES—Indian Summer complicates autumn. It is an imposition of pleasant weather that delays inevitable chill. Gardening is a bit more enjoyable while the weather remains summery. However, late warmth confuses a few species that should decelerate growth for autumn. Deciduous species delay dormancy. This delays the development of autumn foliar color.
Consequently, autumn foliar color is somewhat late this autumn. It is only beginning to develop. Some species that eventually become spectacularly colorful remain very green. Only the most sensitive species, such as Boston ivy, are beginning to exhibit their color. Unfortunately, because of this delay, some may defoliate unusually soon after coloring.
Autumn foliar color is underrated here, for various reasons. It is less common in the wild than in other regions. The color range of native deciduous species is almost exclusively simple yellow. Orange or red are uncommon. This is not much incentive for incorporation of such species within home gardens. Nor does it promote more colorful exotic species.
Autumn foliar color is not much of a priority within Californian landscapes.
Besides, deciduous trees are innately less popular here than within other regions. Local culture seems to promote a preponderance of broadleaf evergreen species. Penetration of warming sunlight through defoliated trees is not such a priority. Winter weather does not get very cold here. Concealment of undesirable suburban scenery is more important.
Also, the misbelief that chill is inadequate here for much autumn foliar color is common. Technically, many of the most colorful species of cooler climates lack such color locally. This unfortunately includes famously colorful North American maples. Several species, however, do not need much chill for spectacular color. They compensate for what lacks.
Sweetgum develops the most vivid autumn foliar color, including yellow, orange and red. It defoliates slowly to retain its color until winter. Pistache is about as colorful, although it defoliates a bit earlier. Flowering pear provides more orange, red and dark burgundy red. Crape myrtle is a smaller tree with comparable foliar color. Ginkgo becomes vivid yellow. Of course, physical traits of each species are also important.
Highlight: Ginkgo
Minimal chill is sufficient for ginkgo, Ginkgo biloba, to develop brilliant yellow foliar color. Mild weather actually enhances retention of foliage after it colors. Colder weather or frost accelerates efficient defoliation. Although less messy, it ruins the spectacular display too soon. Autumn foliar color is monochromatically yellow but is the best yellow of autumn.
Some old ginkgo trees produce messy fruit with objectionable aroma. This characteristic limited their practicality and popularity. Modern cultivars, though, are male and therefore fruitless. Female cultivars are very rarely available, and mostly only by online purchase. Their fruit and the nuts within are edible. However, only mature trees can be productive.
Ginkgo trees grow somewhat slowly but can eventually get taller than 50 feet. Modern cultivars are rather slender and perhaps lanky while young. They retain their elegantly irregular structure as they broaden with maturity. Leaves are about two or three inches long. Their venation radiates outward from their petioles, like fishtails, with paired lobes.
Tony Tomeo can be contacted at tonytomeo.com.
