The lawns in my neighborhood may be brown and dead during this drought, but there are surprising spots of colorful flowers and healthy-looking green leaves — all on vines covering fences, arbors and walls. Three species of vines — bougainvillea, trumpet vines and some grape vines — are extremely drought-tolerant when established. As you consider replacing plants that have succumbed to the drought, put these attractive, vigorous survivors on your list.
Bougainvillea produces bright, showy flowers (actually it's the flower bracts that show color; the tiny flowers grow in the center of the bracts) from late spring to the first frost. Bougainvillea are semi-tropical plants and are extremely frost-tender. In our planting zones (8 and 9 in the central San Joaquin Valley and zone 7 in the foothills) we should plant bougainvillea against a south or west-facing wall that will retain the sun's heat in winter and be prepared to cover the plants, especially the root zone, with frost cloth or other protective coverings when frost is predicted.
Bougainvillea often die back and seem dead even when protected during the winter. Wait until late spring, when new growth appears, to cut out dead wood.
Feed bougainvillea twice a year, in spring and again in fall, with a low-nitrogen fertilizer. Too much nitrogen reduces flower bract production. Bougainvillea have long, sharp thorns so plant them away from high traffic areas.
Trumpet vines attract hummingbirds and bees. Some varieties have fairly short bloom periods; others will bloom all summer long. For continuous summer color, plant several types that bloom at different times.
The tendrils of trumpet vines are really strong; they can lift off roof shakes and pry through gaps in fences and walls. Shear back growing tips on trumpet vines regularly to prevent damage to structures. The vines are semi-deciduous in winter, depending on variety. A once-a-year feeding with a low nitrogen fertilizer should keep them healthy.
Many varieties of grapes can thrive with no additional water in summer. Mine (Thompson seedless) have not been irrigated or fertilized for years; they make do with winter rainfall.
Although the vines would produce more fruit if properly pruned, a whack back with clippers in fall after the leaves drop keeps them under enough control. Immature fruit clusters can be trimmed at the bottom by one-third to produce larger grapes; during heavy bearing years, excess clusters can be left to the birds and squirrels.
Grapes do need a sturdy trellis or arbor to support the weight. Some varieties are susceptible to powdery mildew problems in springtime's warm, wet weather, but fungicides are seldom necessary since our dry summer heat kills off many fungal spores.