Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
October, 2008
Regional Report

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These tulips could be gracing your windowsill in January.

Forcing Bulbs Indoors

If it's fall, it must be bulb planting time. While here in New England we can plant as late as November (I've planted in snow showers at Thanksgiving), an earlier start gives spring-flowering bulbs a longer rooting period before winter. And an early start is especially important when it comes to forcing bulbs indoors, so we can enjoy their blooms on our windowsills while winter still has its hold on our psyches as well as our gardens.

The trick with forcing bulbs is to give them enough chilling so they "think" winter has passed, spring has arrived, and it's time to grow. In cold regions of the country, bulbs will actually bloom sooner if they spend the winter out of the ground. Since daffodils and tulips, for example, need about four months of chilling, if you pot them up and begin chilling them before the end of September, they should be blooming by the end of January. And if you remove some potted bulbs from storage every couple of weeks, you can extend the bulb display into early spring.

Daffodils, tulips, crocuses, hyacinths, fritillarias, galanthus, dwarf iris, muscari, puschkinias, and scillas respond well to forcing, and some bulb labels specify if the variety is especially suitable. In general, shorter varieties work best. Skip the bargain bins and choose top-quality bulbs: the larger the bulb, the larger the flowers.

Potting Up
I use general purpose potting soil and plastic pots. Plastic is lightweight and holds in moisture better than clay, and when I bring the pots indoors to bloom, I slip them into clay or ceramic pots that are more decorative. If I want to mix different types of bulbs together, I pot up bulbs in pots as small as 4 inches for forcing, and then when they start to bloom, I cluster small pots together inside a large planter. Topped with some moss and shells or pebbles, the effect is lovely. I prefer this method to planting them in the same container and risking them not blooming at the same time.

The bulbs put on more of a show if you plant as many as can fit in one pot, so snuggle them together with the tips level with the top edge of the pot. Fill in with soil up to the neck of the bulbs, letting the tips protrude. Water well.

Chilling Out
Now it's time to give the bulbs their simulated winter. They need temperatures of about 35 to 45 degrees (no freezing) for 10 to 16 weeks for optimum flowering. Some general guidelines are:

Daffodil: 15-17 weeks
Tulip: 14-20 weeks
Crocus, dwarf iris, fritillaria, galanthus, puschkinia: 15 weeks
Hyacinth: 10-12 weeks
Scilla, muscari: 12-15 weeks

I've tried all different methods of chilling: in the refrigerator (not enough room), in the garage (too cold), in the shed wrapped in bubble pack (hard to reach for watering). The best spot has proven to be the crawl space under my mudroom, which stays about 45 to 50 degrees. I check on them once a month and water when necessary to keep the soil moist but not soggy.

Bloom Time
Now comes the fun part. When the bulbs have received their required chilling and shoots have begun to grow and roots are visible through the drainage holes, they are ready. Bring them into a cool room that's about 55 to 60 degrees and place them out of direct sunlight for a week to gradually accustom them to "spring." Then get creative with grouping pots together inside larger containers to show them off. Large, shallow baskets lined with plastic are wonderful showcases. I use an antique chamber pot to hold small pots of iris and muscari! I don't mind if my decorative container does not have a drainage hole because the blooming period is short so there's little risk of root damage.

Keep in mind that the cooler the temperature, the sturdier the stems and the more long-lasting the blooms. Hyacinth stems can sometimes be so short and stocky that the buds start to open before the stems have risen above the foliage. You can encourage taller stems by placing a brown bag over the bulbs and placing them in a dark spot for a couple of weeks after bringing them out of cold storage.

Life After Forcing
Tulips get depleted by forcing and aren't worth keeping after the flowers have faded, but other types of bulbs will settle into the ground and bloom the next year if you plant them in spring.

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