Rainer Hunecki
Most likely, you’ve gone to a garden center and made quick purchases of plants that struck you as particularly attractive. I did it myself. Even if you read the label carefully, this plant may lose its luster after a few weeks or may refuse to be ready for the compost bin. Sometimes I don’t discover until years later why kangaroo, jacaranda and avocado paws die prematurely.
Over the years, I’ve learned that as long as a plant shows some green color, it may be worth investigating why it’s sick. The Master Gardeners Help Desk can sometimes assist with this search.
Unless the plant is terminally ill, consider digging it up and finding a more suitable place for it – even if it’s a temporary home in a clean container with fresh soil. I once tried growing a bougainvillea that I had inherited from a friend in Southern California. I put it in a four-gallon pot in a sunny spot across from the house, but one 27-degree night killed it. A mature vine survived just two blocks south of us.
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I tried growing tomatoes in different sunny locations in my Napa garden for at least three years before I realized that most of those areas were infested with soil-borne fungi. No wonder I had such a hard time harvesting a bountiful crop.
These failures taught me some lessons. Crop rotation in the vegetable garden is a sound cultural practice. Vegetables from the same plant family (such as tomatoes, eggplant, and peppers) should not be grown in the same place year after year. Place them on a three-year rotation to discourage soil-borne diseases from getting a foothold.
It is also essential to protect sensitive or delicate plants from harsh weather conditions. My new bougainvillea plants survived last winter with a little frost protection on cold nights, and my hostas are now vibrant in full shade without any direct sun.
Climate change is causing more extreme weather events that can challenge our plants. Maybe it’s time to rethink what we can grow successfully in Napa County. In my own garden, I am testing plants from other Mediterranean climates (Southern Africa, southwestern Australia, Chile, North Africa, Western Asia, Southern Europe) to see how they fare during heatwaves and winter rains.
Most plants in these areas require good drainage. I’ve had success with trees and shrubs that don’t thrive in clay soil by planting them in raised beds or containers. I have had success growing tender plants that say they will not thrive or survive in Sunset climate zone 14 or USDA climate zone 9. By providing frost protection during their first few years, I can keep the plants safe until they become hardier.
I’ve been making my own well-drained peat potting mix to try growing shrubs in the Protea family, and have had reasonable success so far. The Andean holly (Cantua buxifolia) that I planted in a four-inch pot last October in a spot with afternoon shade is now five feet tall. From March to June, it is covered in brilliant purple flowers that hummingbirds love.
I’m thinking of using this plant in a low hedge to visually separate the shed area of our garden. It appears to be more resistant to disease than boxwood, and like boxwood, can easily be pruned into hedges and plants.
I intend to acquire more unusual plants – and perhaps even some trees – in the future to see how they like different parts of my garden. I’ll keep good notes on how they perform, even in the most challenging spots in the dry shade of my backyard.
Food Farming Forum: Join UC Napa County Master Gardeners for “Rooting Root Vegetables” on Sunday, September 10 from 3-4pm via Zoom. Root vegetables grow easily from seeds planted in the warm weather of September, just as the rest of the garden begins to fade. Beets, carrots, turnips and other root vegetables benefit from cool weather, becoming sweeter and juicier as temperatures drop. Learn how to plant and care for these root crops, which you can harvest well into the fall. Register here: https://surveys.ucanr.edu/survey.cfm?surveynumber=40973.
Gardening with Masters: Join the UC Master Gardeners of Napa County on Saturday, September 16, from 10 a.m. to noon, for a workshop at the Ole Health Garden, 300 Hartle Court, Napa. Children are welcome accompanied by an adult. Class size is limited. Register here: https://www.olehealth.org/events/community-outreach-resources/.
Autumn fair: Join UC Napa County Master Gardeners for the “Horticultural Science Fair for All Ages” on Saturday, September 30, from 1 to 4 pm at the Las Flores Community Center, 4300 Linda Vista Blvd., Napa. Get more details here: https://napamg.ucanr.edu/fallfaire/.
Help Desk: The Master Gardener Help Desk is available to answer your garden questions Mondays and Fridays from 10 a.m. to 1 p.m. at the UC Cooperative Extension Office, 1710 Soscol Avenue, Suite 4, Napa. Or send your questions to mastergardeners@countyofnapa.org. Include your name, address, telephone number, and a brief description.
Rainer Hunecke is a Principal Gardener at the University of California, Napa County.
