The weather this winter has been fairly mild. Rainstorms since mid-January have kept the average low temperatures at night from dipping very low, and spring is right around the corner and on time.
As your thoughts turn to gardening, make sure those new plant choices are the right ones for your area.
Some gardening tasks are dependent on the weather. Many shrubs, perennials and grasses should be pruned after the danger of frost has passed, and many vegetables should be started after that time, as well. As a reminder, the estimated date of our last frost is March 15.
I’ve kept a weather journal for my area, the San Lorenzo Valley, since 1992. Based on my records, we might get a few light frosts, especially after a storm, in late March or early April. But for the most part, we have mostly passed the chance of having a frosty morning. Still, it’s a good idea to have a cardboard box or blanket ready to protect your young seedlings.
Knowing the climate in your area helps determine what you can grow in your garden. Notice how much sun or shade an area gets during the growing season — April through September.
Every year, I get asked which zone we are in. It’s confusing in the Sunset Western Gardening Guide, as our area has many microclimates and the map is not detailed enough to reflect this. The guide even shows Felton as being in Zone 7 on a ridge top, instead of on the valley floor.
Another problem with Sunset’s newest book is the typical winter low it shows for each of the three zones around here. For example, Zone 17 (Pasatiempo and the “banana belt”) is described as having lower temps in winter than the Summit. It’s confusing to new and seasoned gardeners alike.
Here are some tips to help you determine in what zone you garden:
n Zone 7 has the coldest winters in our area. Very high ridge tops, like the Summit area and the most northern portions of Bonny Doon, lie in this zone. My records show average winter lows ranging from 15 to 25 degrees, based on 20 years of input from gardeners in these areas. This does not apply to other areas of Zone 7, just those around here. Record lows have occurred during freezes in 1990, 1996 and 2007, but as gardeners, we rely on average highs and lows to help guide our planting times. Spring weather arrives later in this zone, with the growing season mainly from April through October.
n Zone 15 encompasses most of our area. Winter lows average 20 to 30 degrees. The valley floors of both the San Lorenzo Valley and Scotts Valley lie in this zone and are what I call “a cold 15.” Cold air sinks and is trapped in these areas. Often, there is damage to the tips of oleanders and citrus, while gardenias and tropical hibiscus need extra protection. There are warmer parts of this zone, though, where the growing season starts in March and ends in November. Those areas rarely get a freeze after March 15 or before Thanksgiving.
n Zone 16 covers those who live up off the valley floor but below ridge tops, in the so-called “banana belt.” Pasatiempo also falls into this thermal zone. Light frost can occur during the winter, but mostly, the winter lows in this zone stay above freezing.
I hope this helps in choosing plants that will thrive in your garden.
• Jan Nelson, a California certified nursery professional at Plant Works in Ben Lomond, will answer questions about gardening in the Santa Cruz Mountains. E-mail her at ja******@ao*.com.
