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 -50?F, and Zone 11 the warmest, with minimum temperatures never going below 40?F.

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 -20?F/-26?C.

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?

Edible flowers are not only beautiful to look at, they also add color, interest and flavor to meals. Adding flowers to a dish is not a new practice, but it has again become an artful way to add flavor and color to your meals with blossoms from your own garden.

The flavor of flowers ranges from spicy to sweet to herbal. Most flowers are a milder form of their fragrance. Here is just a sampling of the many wonderful edible blooms.

Calendula: Slightly bitter flavor. The petals are used mostly for color. Use for rice, chicken, soups and baked goods.

Chives: Quite flavorful, oniony, but not too much so. Very versatile; use in herbal vinegar.

Nasturtium: Great spicy, peppery flavor. Both blossoms and leaves are edible. Use for salads, vegetables, pasta and meat dishes.

Violas or pansies: Use the whole flower for its wintergreen flavor. Use as garnishes, in salads, desserts, or soups.

Culinary sage: The flavor of the flowers is more subtle than the leaves. Use in salads, soups, chicken and fish dishes.

Marigolds: All varieties have edible blooms, such as Lemon Gem and Tangerine Gem. The flavor is a combination of citrus and spice. Use only the petals in salads, eggs, and soups, as the base of the blooms can be very bitter.

Bee balm: A blend of flavors, citrus, sweet, hot and mint. Pull individual tubular shaped blooms from the flower head. Use in jams and jellies, baked goods, desserts and salads.

Borage: A mild, cucumber-like flavor. Delightful frozen in ice cubes for use in summer drinks. Great candied. Use in salads or as garnishes.

Scarlet runner bean: A delicate bean-like flavor with a slight crunch. Nice garnish for soups, salads and vegetable dishes.

Send your gardening questions to The Garden Doctors at pdgardendoctor@gmail.com. The Garden Doctors, gardening consultants Gwen Kilchherr and Dana Lozano, can answer questions only through their column, which appears twice a month in the newspaper and online at pressdemocrat.com.