When to Plant in Fall
It’s smart to buy bulbs as soon as they are available, otherwise varieties that you desire might sell out. But it’s also smart to resist the temptation to plant them right away if local weather is still quite warm. Fall-planted hardy bulbs are so easy to grow they’re practically foolproof, but planting before the soil cools down can cause problems, especially if the autumn weather turns wet. Most fall bulbs, tulips especially, come from areas where the winters are very cold, but the summers are hot and dry. Bulbs planted in warm, wet soil are susceptible to rot, mildew and other woes.
Fall bulb planting should wait until soil temperatures drop to 55° F (12° C) or cooler. This normally occurs in the fall once the average nighttime temperatures drop to around 50° F (10° C) or lower for two weeks or more. While waiting to plant, store the bulbs in cool, dark place away from direct sunlight. After planting, in a well-drained spot, water the bulbs well. Fall rains normally then kick in, providing all the moisture necessary. This scenario will help bulbs establish strong, deep roots and give you healthy, happy flowers next spring.
Flower bulbs should be planted approximately six weeks before local hard frosts typically begin. You don’t have to be exact. It’s not rocket science; it’s biology. Flower bulbs need time to establish their roots in fall. The stronger the root system, the better able it is to thrive over-winter and put on a good show in spring.
If you goof and winter arrives before you’ve planted, not to worry. Most bulbs really want to grow. Even if you have to plant through snow, get out there and plant those bulbs. Give them a chance: they won’t last the winter without being planted. We’re always hearing from people in January who find bags of bulbs in their garage and worry it’s too late to plant. We tell them: plant them anyway: if you can’t get them in the ground, put them in pots. Chances are good even late-planted bulbs will still bloom in spring. Bulbs are power-packed little units programmed by nature to perform.