Homegrown: Autumn colors to plant around Sonoma County

We usually associate autumn hues with October as diminishing sunlight breaks down the green pigment, chlorophyll, in leaves at an increasing rate after the autumnal equinox. Anticipating winter, leaves begin ending their photosynthetic role of producing carbohydrates that nourish all plants.

An unusual factor this year is that foliage colors have been developing differently. We’re barely past the equinox and significant leaf color has flushed early. We find it mostly on trees under severe stress from prolonged drought, some already dropping leaves, looking nearly dead as they enter dormancy early as a way to manage stress.

In other years when consistent rains begin early and frosts are late, weeks of colors are extended as sugars accumulate in healthy leaves and other pigments build up, yielding bright red and orange, amber and gold, shades of purple and brown. But this year, most leaves aren’t in the best of health from prolonged bouts of high heat and lack of moisture.

Whatever fall weather brings, we notice color changes as pigments that have been in foliage all along begin to assert their own hues while greens in chlorophyll fade away.

Anthocyanin pigments reveal exhilarating shades of red and purple. The yellows, golds, and oranges of carotenoids may stand alone or combine with anthocyanins to create even more explosive hues.

SPECIES SPECIFIC

Within each species, certain colors usually predominate but vary in intensity from year to year. We in the West often hear that our gardens and natural areas can never compare to eastern displays, and it is true.

Eastern forests, home to far more deciduous species than our own, flaunt dynamic, painterly palettes, though the aspens of the Sierra and Intermountain West are a spectacle of their own.

Our mild Mediterranean climate hosts several wonderful species, however, that normally color our landscapes this time of year. Chinese pistache (Pistacia chinensis) and crape myrtle (Lagerstroemia indica) are two favorites, not only for their vivid colors but also for their drought tolerance.

Besides tree size, crape myrtle cultivars also come in a dwarf, shrubby form 3 to 6 feet high. Some develop yellowish-gold fall foliage while others are orange and red.

MORE REDS AND ORANGES

Several sweet gum (Liquidambar) cultivars, such as Festival and Palo Alto, bred specifically for California gardens, develop flamboyant canopies. Drought-tolerant Washington thorn (Crataegus phaenopyrum) also displays exuberant reds, oranges and purples on its small leaves.

Some of the most vibrant color comes with fruit attached, a double delight if you like persimmons (Diospyros kaki). Two commonly planted cultivars, Kaki and Hachiya, both have fiery, orange-red fall foliage.

Gardeners with available space and patience to maintain it enjoy the hybrid native grape, Vitis Roger’s Red. It flaunts flaming red hues but is a rampant grower that needs a sturdy arbor in a location where litter is tolerated.

Despite the show that the ornamental Bradford pear (Pyrus calleryana) puts on in autumn, it’s a tree to avoid because of weak branching structure and tendency to break in high winds.

COLORFUL SHRUBS

Barberry shrubs (Berberis) come in a wide range of sizes and are a colorful boon to gardens, even with their prickly stems. Most turn shades of burnished red with purplish or orange undertones.

Other drought-resistant shrubs that reliably develop warm colors are oakleaf hydrangea (H. quercifolia), nandina, smoke tree (Cotinus) and many spiraeas.

Even monotones can be stunning, such as yellows on pomegranate (Punica granatum) and shrubby native winter hazel (Corylopsis). Kerria japonica, sometimes called Japanese rose, is another graceful, four-season shrub whose small, toothed and corrugated leaves turn from bright green to a rich, buttery yellow.

FALL PLANT SALES

With predictions of a strong el nino heading our way, gardeners are in the midst of fall planting. That should give a big boost to establishing roots by next year’s dry season, especially when we plant California natives and other Mediterranean species.

Besides sales at local nurseries, you’ll find excellent selections at two upcoming events, both on Saturday, Oct. 10.

The annual Native Plant Society sale takes place as always from 9 a.m. to 1 p.m. at the Veterans Memorial Building across from the fairgrounds in Santa Rosa.

The final 2015 plant sale at Jail Industries runs from 9 a.m. to noon at 2254 Ordinance Road at Airport Booulevard, Santa Rosa. Note that only cash and checks are accepted at this sale.

Rosemary McCreary, a Sonoma County gardener, gardening teacher, and author of the book, “Tabletop Gardens,” writes the monthly Homegrown column for The Press Democrat. Contact her at rosemarymccreary@gmail.com or write to her at 427 Mendocino Ave., Santa Rosa 95401.