When to plant hardy bulbs
Hardy spring-flowering bulbs may arrive in garden centres in late summer, but when should they be planted? Early to mid-fall is best, say the experts at the Netherlands Flower Bulb Information Center. For optimal root development, plant them six weeks before the soil freezes hard in your area. The ideal time to plant is when nighttime temperatures are between 5 and 10°C.
Some bulbs, such as daffodils, should be planted earlier to give them more time to develop strong roots. Small bulbs like snowdrops can dry out easily, so plant those earlier, too. Tulips can go into the ground late, just before the hard frosts.
Finally, there is also a group of tender summer-blooming bulbs. Some of the most popular are gladioli, dahlias, tuberous begonias, and calla and canna lilies. Because these bulbs are not hardy in Zones 7 and below, they should be planted after the soil has warmed up in spring.
You can grow summer bulbs as annuals and discard them after one season, or you can dig them up in the fall and overwinter them indoors for replanting the following spring. They’re great for containers, too.
Saving tender summer bulbs
- Dig up the bulbs of tender summer bloomers after frost kills their foliage; remove as much soil as possible. Cut off leaves, leaving a stem 2.5 centimetres long.
- Wash off remaining soil and let bulbs dry; leave exposed to air in frost-free area for a couple of weeks. To avoid rot, make sure stem, if present, is dry before storing.
- Place in vermiculite or dry peat moss (available at garden centres) in paper—not plastic—bags or cardboard boxes in a cool, frost-free place at 5 to 10°C.