‘Tis the Season: Fall Bulb-Planting Tips

Q. Why are my daffodils blooming so much earlier this year than they did the first?

A. Truth is sometimes stranger than fiction. Established perennial or naturalized bulbs tend to bloom about two weeks earlier in subsequent years than they did their first year. This is important to know when you are making bulb selections for color combinations for coordinated spring blooming, especially if you’re adding bulbs to an existing planting. You don’t want to base future estimated bloom times on bulbs’ first year performances. If you do, you’ll find your combinations out of sync down the road.

Q. Do bulbs need to be planted immediately after purchase?

A. In general, the best place for flower bulbs is tucked in the soil of a well-drained, well-prepared garden bed. But if planting must be put off for practical reasons, then take care to store the bulbs in a cool, dry place away from direct sunlight. Excess heat and moisture can harm bulbs. Bulbs stored under proper conditions for a few weeks, but planted at least six weeks before the ground freezes hard, can practically be guaranteed to come up in spring. Of course, not all bulbs are created equal. Certain specialty bulbs have a tendency to dry out if left unplanted, thus should be purchased early in the season and planted right away. This applies to to Colchicum and snowdrops (Galanthus), as well as Erythronium (dog’s-tooth violet), Corydalis, Fritillaria and the rhizome-forming anemones such as Anemone nemorosa and A. ranunculoides.

Q. Are there any flower bulbs that I can plant in fall that will flower in fall?

A. Yes! Try these bulbs for bloom this fall and in future fall seasons:

• Colchicum e.g. byzantinum or ‘Lilac Wonder’
• Autumn-flowering Crocus, e.g., Crocus zonatus, Crocus sativus
• Cyclamen coum (flowers in winter from December to March) in more temperate zones)
• Cyclamen hederifolium

Q. Why don’t flower bulbs in the ground freeze in the winter?

A. Bulbs are designed by nature to withstand cold winter temperatures. Indeed they rely on winter’s cold to trigger the biochemical process necessary to bring the bulb to flower in spring. While winter soil may actually freeze to depths beyond which the bulbs are planted, soil temperature will rarely fall below 29F or 30F. At these just-below-freezing temperatures, water in the cells of the bulb may freeze but the cells will not be harmed. Also, as is true for many hardy plants, cold temperatures trigger starches in bulbs to break down into glucose and other small molecules. This simple sugar or glucose, interacting with other small molecules, acts in much the same way as salt on a winter sidewalk. The sugar in the bulb, like the salt on the sidewalk, lowers the temperature at which water freezes. This fortunate chemistry helps to keep bulbs safe and snug in their winter beds. Other factors that help keep soil temperatures within tolerable limits include an insulating snow cover and, in colder areas, a nice layer of mulch over the bulb bed once the ground temperatures have dropped.

Q. When is the best time to plant tulips, daffodils and most other bulbs in fall?
A. In most areas, the “window” of time for planting bulbs in fall is fairly wide. Here is a practical way to plan:

• Time to start planting bulbs: once night-time temperatures drop into the low 50s or 40s for two weeks.
• Time to finish up: once hard frosts are coming. Generally bulbs root best in the period six weeks or more prior to the ground freezing.
• After planting bulbs: water the site well. Typically, fall rains will take over this task for the balance of the season.

Q. What if it’s already early winter and I still haven’t planted my bulbs?

A. When best plans fail and you still haven’t planted your bulbs by early winter, the answer is – just plant the bulbs as soon as you can, even if you have to chip into the ground. Bulbs are not dormant, they’re alive – and they won’t last much longer if left unplanted. If you can get them into the ground (either in pots or in the garden), chances are good that they’ll grow. If you don’t plant them soon, you may as well toss them out.

Bulbs that get less than 10 to 14 weeks (depending on their type) of sustained cold temperatures still come up but may be shorter than usual. If they are types or varieties that perennialize or naturalize, they’ll come back normally in future years if their foliage is left to die back after bloom in spring.

If you know in advance you won’t be able to plant until very late, throw small tarps or leaf piles over proposed planting areas to keep the soil warm and workable until you are ready to dig.

Expert gardeners have one more late season trick up their sleeve: they pot up unplanted bulbs for indoor forcing, or as container plants. With containers, you have the advantage of being able to control the initial soil temperature by adding your own soil. Choose the light potting soil mixes sold at all garden retailers. Move small containers to an unheated garage or other cool, yet protected place. In spring, use the potted bulbs as accent plants or bring them indoors. Remember these are last ditch measures. Once the time for fall planting has arrived in your area, the sooner bulbs are safely in the ground, the better.

For more information on fall planting visit www.bulb.com.