Seek Local Native Plants for Cold (and Hot) Tolerance

“One of the advantages of growing local native plants is that the plants from your immediate vicinity are well adapted to our climate’s yearly fluctuations and can take those rare days with winter low temperatures and high temperatures in the sumners” – Bart O’Brien, RSABG

Here in California we’ve had some unusally cold weather this January, with temps dropping into the mid to high-20s for several nights in a row.

Like many, I roamed my yard the following mornings to assess the damage. The coleus, despite being tucked under an eave, is likely a casualty and a few avocado trees got nipped.

But it was nice to see the California native plants came through unscathed. There’s even some nice blooming and busy bees on our manzanitas and of course the non-native rosemary that grows so well here.

Rancho Santa Ana Botanic Garden (RSABG)’s Bart O’Brien, said their nursery plants in Claremont and Westwood did well because very few California native plants are frost sensitive. “Generally speaking, the only ones that we have ever had frost damage on are a handful of plants from the California and Baja islands and a few from the low deserts.”

This seems to fit our experience since some of our Agave Americana, which originates in Mexico, got rubbery and our South American sage (salvia) species got nipped.

Going local

• O’Brien recommends natives from your area. “One of the advantages of growing local native plants is that the plants from your immediate vicinity are well adapted to our climate’s yearly fluctuations and can take those rare days with winter low temperatures into the 20s as well as those high temperatures over 115 in the summer.”
• To learn what those are, start with your state’s native plant society, which shows up easily on internet searches. Similarly, searches should uncover native plant nurseries and botanic gardens in your area or state.
• For California residents, Las Pilitas Nursery has a webpage – www.mynativeplants.com – that helps determine what plants are native to your area. You type in your zip code and a list of recommended plants pops up – quite helpful.
• Another helpful webpage of theirs discusses the hardiness and cold tolerance of California natives. In our inland area, plants that best tolerate ground freeze are from the chaparral and coastal sage scrub communities. Manzanitas, oaks, sugar bush, monkey-flowers, wild currants (ribes), toyons, various sages (salvias) and wild lilac (ceanothus) are common plants in these communities.

Bert Wilson, who owns the Las Pilitas nurseries in Escondido and near St. Luis Obispo, also said their nurseries fared well. “The lower elevation California native plants start dropping like frozen lettuce at about 5 to 7 degrees, and the Sonoran Desert species do not take any frost well.”

Take a trip to a Local Native Plant Garden

Many arboretums and botanic gardens now feature a native plant section while some, such as RSABG in Claremont, and Caroline Park here in Redlands, focus solely on natives. Caroline Park’s champion, Dr. Harold Hill, said they’ve never had severe frost damage. “If it’s a plant we recently planted so it’s young and tender, there might be some damage, but they survive,” he said. Blooming should improve with another good rain or two, but the wild lilac are budding out, with their bright blue blooms on plants at the Sunset Drive turnout. And on the lower end of the park, the coyote brush is in full whitish splendor.

Leave frost damage for protection

It’s difficult, but the best thing for any damaged plants is to leave them as they are. Those dead leaves provide protection for the living parts of the plant. But sometimes it’s obvious there’s no hope. In those cases, consider a native plant as a replacement. It’s still a great time to plant natives because the cold months allow the plant to establish roots before our heat no doubt hits once again.