Can you believe how vivid the reds of some varieties of Japanese maples are? And the Chinese pistache aren’t looking too shabby, either.
Those colors are always there. They’ve just been just masked by the chlorophyll in the leaves, which was busy making food by photosynthesis while the sun shines.
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 those colors — red and purple anthocyanins, 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 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, meanwhile, can cause leaves to drop suddenly, denying them the opportunity to enter their slow, colorful dormancy.
Finally, trees under stress — because of pests, disease, injury or drought — may drop leaves with no color change at all.
I read that the foliage hasn’t been great in Vermont the past couple of years, so enjoy the beautiful spots of color we do get, along with our fabulous weather.
I’ve received an e-mail about when to expect our first frost.
I’ve kept a weather journal since 1992, and based on my records, on Oct. 29, 2002, we had a light frost. Mostly, though, the earliest frost occurred the second week of November, with late November being the most common. From 1997 to 1999, the first frost was in the first week of December.
Be prepared by taking in houseplants and moving frost-tender plants under overhangs.
Now’s the time to move plants or install them out of containers and into the garden soil. October through February offers the best times to do this, but the sooner the better. Soils are still a bit warmer, and rains are less frequent.
Transplanting and installing succeeds best if you take care of the roots as well as the top of the plant. Good growth comes from root health.
- 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 when digging. Cut roots will form new, dense and healthy roots.
- Before replanting from a container, check for roots that have circled the interior of the pot. These must be tugged loose and straightened. Don’t be shy about loosening roots.
- When replanting, be certain to keep the rootball at the same level it was. This also holds true for plants coming out of containers. Don’t add soil over the rootball. Most plants need oxygen at the soil level.
- Check your trees, shrubs and perennials in containers to be sure the roots have enough space.
Rearranging the garden makes for satisfactory fall work.
- Jan Nelson, a California certified nursery professional at Plant Works, will answer questions about gardening in the Santa Cruz Mountains. E-mail her at firstname.lastname@example.org.