Stick with plants that can handle our cold winters

A few years ago, USDA decided our area had warmed up, so re-assigned us from hardiness zone 6 to 7, indicating an expectation that our winters would not be colder than 0 degrees F. I think every winter since then, our temperatures have fallen below zero. Gardeners are far safer concluding we’re in hardiness zone 6, and buying perennials, trees and shrubs that are hardy to that zone, not 7.

If you’re going to plant a specific plant in a container that will remain outdoors, plan on only using one that’s hardy to zone 4, because the plant will not have the protection of a mass of surrounding soil.

Yes, there are such things as microclimates where temperatures are warmer, and cold winds don’t intrude, but for the most part, we have zone 6 winters. If you’re new to this area, the Sunset magazines and Sunset’s Garden Book are very good resources, BUT Sunset uses its own criteria for establishing zones, and wholesale nurseries don’t follow their lead. Sunset’s zone for this area is 3, and it bears no relationship at all to the USDA hardiness zones or the American Horticulture Society’s heat zones. In my experience, wholesale growers do not give AHS heat zone or Sunset zone designations on plant labels. Whether or not a plant can take our summer heat and bright sun is a consideration for gardeners.

Our average last date of frost is about May 9, but nights may continue to be chilly, so it’s a good idea to wait until about June 1 to put out tender plants such as chiles or tomatoes. A cold night or two (even above freezing) can disrupt diurnal rhythms for the rest of the season, resulting in smaller harvest than you should get.

• • • 

Human scientists have not been idle since they created new life forms that were combinations of animal and vegetable by genetic engineering. About all we can do is hope that originators of these new genetically altered organisms will allow independent, objective testing of their products so we can be assured of safe food in years to come. Monsanto’s reassurance devoid of independent objective testing was not entirely trustworthy, since that firm would benefit by sales of that technology.

Newer forms on the market include:

CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats

Cell Fusion CMS: Cytoplasmic Male Sterility

I can’t explain these techniques, and I suspect only people who’ve been in agricultural college settings within the past five or 10 years could. The Bountiful Gardens catalog says the CRISPR technology is “gene editing” and a “cheap, easy and irreversible” genetic modification, and CMS technology produces plants that may make seeds without pollen, fitting the International Organic definition of Genetically Modified Organizations, but not the U.S. definition. The implication is that the CMS seeds could be sold as non GMO hybrids in the U.S.

By irreversible, they mean the changed characteristics are transmitted to progeny.

So we’ve got to be alert to these altered seeds if we want to avoid GMOs.

• • • 

Most of us have seeds left over from other seasons, but we know that, after a time they are too old to germinate. Seeds not only contain the germ of a plant, but also the food for that plant until it can begin making its own food from photosynthesis (leaves and green stem). How can you tell whether your seeds are still viable?

Count out 10 seeds and put them on a paper towel or coffee filter dampened in tepid water, fold the towel or filter over the seeds, put them in a resealable plastic bag, seal it and put it in a warm place such as the top of your refrigerator. After a few days, open the bag and look for tiny white roots poking forth from each root. If, for example, there are five seeds with roots, you have 50% germination, and you should then plant double the number of seeds you’d plant if they were fresh.

This story was originally published January 18, 2017 at 4:02 PM with the headline "Stick with plants that can handle our cold winters."