Gloria C. of Santa Rosa asks: How can I tell if old seeds are still viable?
If you are in doubt about the viability of leftover seeds, there's no need to take chances.
You can easily find out by doing this simple germination test: Moisten a coffee filter or paper towel and place about 10 or 20 seeds on it.
Fold the moistened paper over the seeds and put it inside a clear plastic bag in a warm place.
Take the paper out and inspect the seeds at least once a day, spraying with water as needed to maintain moisture on the seeds.
After the usual number of days required to germinate that variety, count to see how many seeds have germinated and calculate the percentage of germination.
If more seeds than not germinated, your seeds are fine to plant. If germination is much lower or slower than expected, order new seeds.
Kathleen T. of Sebastopol asks: What do references to “zones” mean, and how do I determine which zone I'm in?
Zones refers to geographic regions of plant hardiness, which are based principally on the average annual minimum temperatures. There are 11 hardiness zones in North America. Zone 1 is the coldest, with minimum temperatures of -50F, and Zone 11 the warmest, with minimum temperatures never going below 40F.
Plant hardiness is rated by the lowest temperature at which the plant can survive.
For example, if a plant is described as being “hardy to Zone 5,” that means it will survive in areas where the winter temperatures go as low as -20F/-26C.
The USDA Map of Hardiness Zones allows you to click on your area to find your zone and a list of the lowest temperatures that can be expected. Or, you can determine your zone by your zipcode and learn more about plant hardiness zones by visiting the website of the National Gardening Association.
Cathy K. of Healdsburg asks: Since I love flowers and appreciate good food, can you tell me what flowers I can grow that have edible flowers?