- Find out what the average first frost (in the fall) and average last frost (in spring) dates are in your area. Your local county extension office or a good plant nursery will have this information. See Resources for a link to detailed information about average first and last frost dates by state and town. These dates will give you places to start when figuring out when to plan your planting.
-
The northwest United States comprises several climactic regions. These are divided into zones. (See References for zone maps.) Sunset (gardening magazines and books) has developed its own zoning system, used extensively by western gardeners. A link to their map is listed in Resources.
When to plant bulbs will depend on where you live, and what type of bulb you are planting. Fortunately, bulb growers and sellers take this into consideration, and usually make the bulbs available for purchase in each area at about the right time to plant them. In any case, you should buy the bulbs you want as soon as they appear in the stores, because even if it's not time to plant them yet, you can provide better storage conditions at home than they will experience at the shop. - Bulbs that bloom in spring must go through a cold period before growing. That means winter. But you have to give the bulb roots time to get established before the ground freezes, so count back six weeks before your soil usually freezes hard. When might this be? Look for nighttime temperature of about 50 degrees (F) or less, and soil temperatures of around 55 degrees. Plant your bulbs. If you do it too soon, in warm soil and wet weather, your bulbs will likely rot.
- Plant canna lilies and dahlias after frosts have stopped. For gladiolas, anywhere from April through June might be right, depending on your climate. Most crocus bloom in early spring, but there are fall blooming varieties. These you would plant when they are available in the late summer. Cyclamen should be planted when they're dormant, June through August. The most easygoing bulb around is the daylily. You can plant it anytime, and it will bloom happily when it's supposed to.
