Category Archives: last frost date

The November Garden

Cercis_Forest_PansyOutside my window, the Forest Pansy Redbud has started to display its spectacular burnt orange fall color. Thereís a suet feeder hanging from the branches so I get to enjoy the antics of the Pygmy Nuthatches, Purple Finches and the Chestnut-backed Chickadees all day long as I watch the changing colors of the foliage. Out back I have a Catawba Crape Myrtle also starting to show fall color. Its leaves are turning a rich butterscotch shade which is lovely but not the reddish-orange described in the books. What causes fall color to vary from plant to plant? How does location in the garden, weather, climate and growing conditions affect what you see each fall?

The brilliant fall color we see in the leaves of trees and plants is always there. Itís just masked by Japanese_Maple-fall_color.1280chlorophyll during the growing season as the plant is busy making food while the sun shines during photosynthesis. Come autumn, shorter days and cooler temperatures cause the trees to switch into energy-storage mode, at which point their leaves stop producing chlorophyll. For the few weeks before the leave fall to the ground, they are colored only by their natural pigments. It’s these colors – red and purple anthocyanins and yellow and orange carotenoids that make fall foliage so glorious.

Some years the show is more dramatic than others. The best conditions for intense leaf color to develop are dry sunny days followed by cool, but not freezing nights. A warm, wet autumn will almost surely result in less-than-spectacular foliage because the process of chlorophyll loss will be less consistent. Freezing temperatures or winds meanwhile can cause leaves to drop suddenly denying them opportunity to enter their slow, colorful dormancy. Finally, trees that are under stress because of pests, disease, injury or drought may drop their leaves with no color change at all.

Japanese_Maple-fall_color2.1280So if your garden becomes shady early in the fall this may result in less vivid fall foliage. If your trees are stressed by drought like this year you may not get the usual colorful fall display. These and the above factors all affect the intensity of fall foliage colors.

Now is a good time to shop for plants and trees that can punch up the color of fall in your garden. Seeing your new addition in person will show you exactly what color you are going to get. Sure Autumn Gold Ginkgo will probably always color up bright yellow and Sango Kaku Japanese maples will show off their characteristic golden foliage but the fall color of Purple Smoke Bush, Katsura tree, Witch Hazel, Pomegranate, Oakleaf Hydrangea and Blueberry, to name just a few, can vary.

First Frost
I received an email from someone new to the area about when to expect our first frost. I’ve kept a weather Japanese_Maple_Sango-Kaku_fall_color.1600journal since 1992 and based on my records occasionally we get a light frost at the end of October. Mostly though, the earliest frost has occurred about second week of November with late November being the most common. Be prepared by moving frost tender plants under overhangs if possible or having frost blankets (not plastic) ready to cover delicate plants.

Transplanting in Fall
Need to move a plant or install plants out of containers and into the garden soil? Now through February offers the best time to do this. Soils are still warm at this time of year which helps new roots get established quicker than in later winter.

Prepare the new location first before excavating any plant. Dig a hole twice as wide as the rootball, but just the same depth. Use a sharp spade to make clean cuts through roots. Cut roots will form new, dense and healthy roots.

Before replanting, especially from a container, check for roots that have circled the interior of the pot. These must be tugged loose and straightened when planted. Don’t be shy about loosening roots. When replanting be certain to keep the rootball at the same level it was and don’t add soil over the rootball. Most plants need oxygen at the soil level.

Gardening zones & last frost in the Santa Cruz Mtns

The weather this winter has been fairly mild. Rainstorms since mid-January have kept the average low temperatures at night from dipping very low. 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 are to be pruned after danger of frost is past and many vegetables should be started after this time as well. As a reminder the . I’ve kept a weather journal for my area, the San Lorenzo valley, since 1992.  Based on my records, we may 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, from April through September. Every year I get asked which zone we are in. It’s confusing in Sunset Western Gardening Guide as our area has many microclimates and their map is not detailed enough to reflect this. They even show Felton as being in zone 7 on a ridge top instead of on the valley floor. . Another problem with Sunset’s current book is the typical winter low they show 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 both new and seasoned gardeners alike. Here are some tips to help you determine in what zone you garden.

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 15-25 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 comes later in this zone with the growing season mainly from April – October.

Zone 15 – this zone encompasses most of our area.  Winter lows average 20-30 degrees. The valley floor of both San Lorenzo 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.  These areas rarely get a freeze after March 15th or before Thanksgiving.

Zone 16 – those who live up off the valley floor but below ridge tops live in this "banana belt". Pasatiempo also falls in 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.