What do you need to do in winter to keep your California native plant garden thriving?
The following tips are geared towards gardens in California’s Central Valley and Southern Sierra Nevada. These ideas can also apply to gardens that share similar traits:
1) Inland – Little or no ocean influence means cold winters and long, hot summers.
2) In the Central Valley, ground fog provides additional winter precipitation.
3) On clear nights, low temperatures can be below freezing for several hours.
In these conditions, we can plant well into December, as long as we cover the soil with mulch and have our irrigation system ready.
So far this fall, we’ve had warmer-than-average temperatures and abundant rainfall, which has made it a great season to plant.
For any plants that are not reliably frost-hardy, wait until after frost danger to plant. This includes species that originate in Baja California and the channel islands.
If you have a newly-planted garden, mulch mulch mulch. This protects the soil from freezing and keeps the soil moist between storms.
If we have a long period without rain, check the soil around your new plants. If it is dry below a few inches, run your irrigation system. Your new plants should not completely dry out at all this first winter, but the first inch or two of soil can be crumbly and fairly dry.
If your new plants don’t seem to be growing, but otherwise look fine, don’t worry! If foliage isn’t growing, roots probably are, and that will be better for your plants’ long-term success. So, relax and be patient. You will see foliage and flowers once the weather starts to warm up again.
Please don’t be tempted to fertilize your new native plants. They don’t need the extra nitrogen, and new tender foliage is the first to freeze, which is stressful to the plant.
For established gardens, you may see some late flowers, due to the warm fall, especially on species like California goldenrod and fuscia. These are among the herbaceous perennials that often die to the ground once a good frost occurs.
In that case, don’t rush out and cut away all that frozen, brown, dead foliage. Leave it to protect the plant’s crown during the next frost. Remove frost-killed foliage once the weather has warmed and you see new green growth.
What about pruning? It is fine to prune fully dormant trees and shrubs anytime before spring.
For evergreen trees and shrubs and perennials, wait until after frost danger to prune heavily. Light hedging or removing dead material should be okay.
Frost and freezing temperatures are not that stressful to mature, frost-hardy healthy plants that don’t have a lot of new tender growth. If some of your plants were severely stressed by drought this summer, you may want to limit the pruning you do this year if you can.
Did I mention mulching?
Happy Winter. Let it rain! Let it snow!