In a couple of days, we will be moving back to Sonoma County, so this will be my final blog for the Solano Program. We will miss being in this nearly frost-free climate of zone 17, but we are happy to be back in a forested rural area. Our home in Occidental is in Sunset’s zone 15, where winter temperatures can dip into the upper 20’s during a cold snap. The New Sunset Western Garden Book shows a detailed climate zone map of the entire Bay Area (pages 32,33), including the inland Delta areas. Aside from the milder zone 17, Solano County includes a big chunk of zone 15, 14, and 9, which is near Vacaville.
Companion Planting
One way to beat the frost is to plant the most sensitive plants, like Lantana (Lantana camera) with some other more frost hardy plant, like California lilac (Ceonothus spp.) (see photo), seen cascading over a retaining wall in my neighborhood. The evergreen foliage protects most of the sensitive parts of the Lantana as an unexpected symbiosis.
Bougies to Go
For those of you like me who can’t stand to go without a Bougainvillea (Bougainvillea spectabilis), my solution to zone 15 living is to pot them, which makes them portable and easily placed in a protected place during a frost alert. (see photos)
Break out the Frost Covers
And yes, I’ve found that you can have avocados (Persea americana) in zone 15. But you do have to keep the frost covers handy during the coldest months. We have two at our Occidental condo, and I got the hardiest ones I could find: ‘Mexicola’, which is very cold hardy to 20 degrees F. The Meyer lemon (Citrus x meyeri) is also a favorite of mine. It’s best to get early ripening varieties in frost prone areas, because fruit is damaged at several degrees below freezing. However, frost covers can raise the temperature by 6 degrees, which often is just enough to protect the fruit.
Late Blooming Apricots
I had given up on trying to grow apricots (Prunus armeniaca) in zone 15, but recently I found two late blooming varieties: ‘Harcot’, and ‘Harglow’. The latter is also disease resistant. So, I’ll be putting one or two dwarfs in, in another month or two.
Enjoy this beautiful fall weather.
