Garden Planner: Adding Summer Color

Tough Love
Gardeners now share the cut-flower industry’s love affair with South Africa’s conebushes (Leucadendron), pincushions (Leucospermum) and protea, all admired for their showy foliage and otherworldly flowers. Succeeding with these tough beauties in home landscapes still requires some TLC. Essentials include sharp drainage (slopes are ideal) and good air circulation with protection from drying winds. Amend alkaline soils with organic material and sulfur to increase acidity. Provide regular water until established; then limit irrigation to once or twice a month. Avoid fertilizers with phosphorus, and treat leaf-yellowing chlorosis with iron. Take care to leave roots undisturbed during any garden maintenance.

Do Like the Zoo
​Like the San Diego Zoo’s animal exhibits, its horticultural collections are fascinating. As this civic institution celebrates its centennial, Zoo Curator of Horticulture Stephanie Shigematsu suggests five crowd-pleasing plants on its grounds worthy of home gardens. 

1. Sesame Succulent (Uncarina grandidieri) This velvety-leafed perennial from Madagascar, by the iguana exhibit on Reptile Walk, blooms for months with dark-throated, yellow, petunia-like flowers.This deciduous species grows 9 feet and taller. 

2. Mt. Elgon Aloe (Aloe elgonica)
Part of the zoo’s accredited aloe collection, this clump-forming Africa native has thick, recurved leaves blushed with pink and edged with broad teeth. From spring through summer, bold red flower spikes lure hummingbirds.

3. Shoestring Acacia (Acacia stenophylla)Stephanie describes this Australian native with twisted, blue-green leaves and creamy yellow spring flowers as “neat, narrow and drought tolerant.” Planted at Elephant Odyssey, it is among many acacias harvested by the zoo to feed animals fresh greens.

4. Queensland Bottle Tree
 (Brachychiton rupestris)
“This is a show-stopper,” Stephanie says of this tall tree from Down Under with a swollen trunk topped by a lush fan of leaves. Red and cream flowers follow foliage drop in spring. See two in the zoo’s Elephant Odyssey near Sabertooth Grill.

5. Tecate Cypress (Hesperocyparis forbesii) This handsome San Diego County native stands outside the condor exhibit. It is a fast grower tolerant of clay soil and the only plant where rare and endangered Hairstreak butterflies lay eggs. 

In the Know
Alpine-based landscape designer Steven Harbour worked for a decade on what he calls “a crash course in the design of drought-tolerant outdoor spaces.” The New California Landscapes (Steven Harbour, 2015) offers techniques for planning and maintaining dynamic landscapes. The book profiles best uses of 300 water-wise plants. Details are at steveharbourlandscapes.com

Mildew Dos
Powdery mildew coats leaves and stems with a disfiguring white growth. Affecting a host of plants, the pervasive fungus thrives in June gloom’s moderate temperatures and humid air. Oddly enough, it needs a dry plant surface to become established. When a powdery white growth appears, use a strong blast of water to destroy and dislodge fungal spores. This is best done early in the day so that plant surfaces dry before nighttime. Horticultural oils and fungicides appropriate for the affected plant also can be used. If mildew is an ongoing problem, replace afflicted plants with resistant varieties and plant them where there’s plenty of air circulation and sunshine. For more information on this and other plant diseases, visit ipm.ucdavis.edu.

June Prune
When the first tiny apples, pears or peaches appear in home orchards, you can almost taste the juicy, sweet fruit to come. Then comes “June drop,” when trees suddenly shed what seems like too many of the marble-sized fruits. This self-pruning elim-inates excess fruit and focuses the trees’ energy on the remaining crop. Experienced gardeners often aid this process by further reducing the crop, leaving only one fruit per spur on every 4 to 6 inches along a branch. Ripened fruit likely will be larger and more flavorful as a result. Other trees that benefit from fruit thinning include plums, persimmons and apricots.

Fruit With Appeal
Only one of the 1,000 banana varieties in the world usually shows up in supermarkets. Fortunately, these broad-leafed plants thrive in frost-free areas, bringing San Diego gardeners exotic homegrown bananas, some with apple, mango or papaya flavors. Varieties to cultivate locally include cold-hardy ‘Orinoco,’ grown in California for decades; Honduran-bred ‘Sweetheart’; ‘Cardaba,’ which is ideal for cooking; and ‘Cuban Red,’ an exotic, red-skinned variety. Plant in full sun and well-draining soil, and water regularly. Expect fruit within two years after planting. For more information and retail sources, join the banana forum via a link on the website of the California Rare Fruit Growers’ San Diego chapter (crfgsandiego.org) or visit the chapter’s booth at this month’s San Diego County Fair.

Family Trees
Is Dad a fan of apples, oranges, peaches or plums? Surprise him on June 19 with a premium fruit tree delivered and planted by The Wishing Tree Co. The Father’s Day Gift Tree package from the Encinitas-based company includes delivery of a 15-gallon garden tree or 5-gallon patio tree, planting, boxed-tree care essentials and an engraved tree tag commemorating your gift. Pick a special tree — or let Dad choose his favorite. Custom-grown, locally sourced shade and ornamentals are available. Through June, save $50 on $195 garden trees and $20 on $145 patio trees using promo codes DAD2016 or DAD2016PATIO at thewishingtreecompany.com.

Address Change
San Diego Master Gardeners, like everyone else, have grappled with the impact of climate change in their gardens. So it’s no surprise that their annual spring garden seminar on June 4 is themed “Gardening in a Changing Environment.” The daylong event at San Diego County Operations Center taps 18 local experts to teach classes on everything from rainwater storage to new tree pests and practical ways to cope with fickle weather. The seminar also features workshops and sales of plants, books and birdhouses. Register online or sign up for still-open classes on seminar day. Details are at mastergardenerssandiego.org.

And don’t forget to:

• Check the schedule for Flower Show Stage speakers when spending the day at the San Diego County Fair (June 3-July 4). The talks, free with admission, feature local experts on popular gardening topics.

• Cover pools and spas when not in use to reduce evaporation.

• Frolic with daughters and granddaughters at the Hamilton Children’s Garden Fairy Festival on June 18.

• Use sun power or solarization to kill turf you plan to replace with a water-wise garden. Learn how at turfreplacement.watersmartsd.org. 

• Learn about composting at free workshops around the county hosted by the Solana Center for Environmental Innovation. View a schedule at solanacenter.org.

• Move potted succulents sensitive to searing summer sun into areas with dappled afternoon shade.

• Add summer color by planting six-pack seedlings of zinnias, cosmos, Mexican hats (Ratibida), Mexican sunflowers (Tithonia), marigolds, black-eyed Susans
and coreopsis.