As summer wanes, a lusty crop ripens along the branches of local oaks. These substantial seeds soon fall and elicit complaints from tidy-minded folk upset by the bullet-like acorns shed across lawns and scattered over sidewalks. For alert gardeners, however, the moment presents a chance to harness a force of nature. Within each capsule lies miraculous power: the capacity to change windswept prairie sun to gentle shade, to fundamentally alter the surface of the planet for generations. What might become thousands of majestic trees now hangs on branches and lies on the ground, ready for gathering.
It is, of course, an act of faith to plant an oak from seed, knowing that it will be years before its shade extends very far. The truth is, those magical packages, the acorns, can grow quite readily, and the deeply spreading root systems that make oaks so adaptable and well suited to the nutrient-poor soils and uncertain climate of this region often develop best when initiated by direct seeding. Gardeners can also participate in the selection process by gathering acorns from particularly good parents. If you find an exceptional spreading live oak, a flaming, burnished Spanish oak, or a giant-leafed bur oak growing successfully in a local garden, their progeny may be better investments than large trees of unknown pedigree or provenance.
Several beautiful native oaks adapt to gardens with alkaline soils. In their habitats, these trees seem to ripen acorns from west to east, with oaks of the Chihuahuan desert, such as Chisos red oak (Quercus gravesii) and silverleaf oak (Q. hypoleucoides), usually shedding in late August. These elegant species, common to the Davis Mountain region and elsewhere in far western Texas, are both worthy of garden space.
In central Texas, where I garden, the Lacey oak (Q. laceyi), with smoky blue-gray foliage turning yellow in fall, and Vasey oak (Q. pungens var. vaseyi) usually ripen seed in September, followed by escarpment live oak (Q. fusiformis), chinquapin oak (Q. muhlenbergii), and Texas red, or Spanish, oak (Q. buckleyi) between Halloween and Thanksgiving. The chinquapin and the Spanish oak often drop acorns as their foliage turns to autumnal russet, making it easy to select the best color forms. The behemoth bur oak (Q. macrocarpa) usually releases its mammoth acorns in late November as it sheds coarse, lobed leaves, followed by the Mexican white, or “Monterrey,” oak (Q. polymorpha; see “Worth Growing,” below).
All of these oaks offer powerful landscape forms, often defining a scene with their majestic proportions or rugged character, sometimes springing from a tall, single bole, sometimes growing as a romantic, multistemmed “mott” (an early Texan term derived from the Spanish mota, or clump). These are reasons enough to have them in gardens. The reasons to gather acorns and engage in the long process of watching over several years as a young tree develops from its earliest cotyledon stage to an incipient giant, may seem more obscure to gardeners in the present era of self-conscious landscape designs and “extreme makeovers.” But it shouldn't, for any real garden is more about process and relationship than a certain result, and the joy, as with our own lives, lies in the growing.
WORTH GROWING: Mexican white oak, Quercus polymorpha
This evergreen oak ranges from the mountains of Guatemala northward through the sierras of eastern Mexico, growing at progressively lower elevations until it reaches its northernmost stand in a small grove along the Devil's River in southwest Texas. It has become a popular landscape tree over the last decade, valued for its speedy growth, adaptability to dry, rocky soil, and good, magnolia-like form when young. True to its botanical name, this mostly Mexican species varies in character and leaf shape. Some trees exhibit attractive purplish new growth, and the oblong leaves often display a bright yellow petiole. These variable oaks may become briefly deciduous in late winter or in response to unusual cold. Another beautiful Mexican oak, Quercus germana, is similar. Hardy in USDA Zones 7b–11