Forcing Bulbs

Spring Color in the Dead of Winter

Stimulating plants to flower when it's not their normal time to bloom is called "forcing." Many spring bulbs can be forced indoors, and they will add welcome color during the gray winter months. Tulips, narcissus (daffodils), hyacinths, crocus, muscari (grape hyacinths), scillas and other bulbs can be forced into bloom in mid-winter.

Bulbs can be forced in almost any type of container. Because roots are not long, the pot does not have to be deep, but its size is important: it must be large enough to hold the bulbs comfortably without touching each other or the sides of the pot. Bigger is not better, either – too large a pot, the plant may not grow as well.

A bulb has three stages to develop and flower. First is the chilling period, which is essential for the development of a sturdy root system. Typically, daffodils, tulips, and hyacinths need 6-8 weeks of chilling, at a temperature of 40-50 degrees. A refrigerator serves nicely if you have the room. Once bulbs have this chance to develop their roots, gradually move the pot into warmer conditions with more light. This gives them a chance to adjust to the light, and allows root development to continue. Bulbs are ready for the final stage when flower buds are well out of the bulb, and often showing color. At this point, you can move them into full light – a cool window is a good spot. During flowering, keep the plants cool and moist to encourage a longer bloom time. Too much heat can ruin the flower buds. Keep the pots watered throughout the blooming period, as the rapid growth of the bulbs requires increased watering.

To pot your bulbs for forcing:

Fill the container halfway with sterile potting mixture. Set the bulbs in the pot, with space between so they do not touch. Be sure you place bulbs so that the "pointed" end faces up. Cover bulbs completely, making sure you work potting mixture down between the bulbs. (Hyacinths, narcissi and amaryllis bulbs should have about 1/3 of the bulb above soil level.) Firm mixture enough that the bulbs are supported, but not packed so tightly that roots cannot penetrate. Leave about 1/2" - 1" at the top of the pot for easier watering.

After planting, water bulbs thoroughly.

On the average, bulbs will flower 3 to 4 weeks after forcing. Continue to water the plants while they bloom and the foliage ripens. If you want the bulbs to flower again, fertilize with a high phosphorous houseplant fertilizer to encourage healthy green leaves since this is how the bulbs will store energy to bloom again.

You'll have best results by placing your bulbs in a cool location at night, keeping them well-watered, and out of direct sunlight. When the plants have bloomed, allow the foliage to continue growing until it dies down naturally. Then remove the bulbs from the pot and store them in a cool, dry place. If possible, plant the bulbs in the spring at their normal depth in the garden - about 6" deep for large bulbs and 2"- 3" deep for smaller bulbs. Most bulbs will not force a second year, but hyacinths and daffodils will flower outside the following spring if properly ripened after forcing.

Amaryllis

Most amaryllis, and certainly J&P bulbs, are ready to get growing as soon as you get them – they have been pre-chilled and conditioned to sprout. Plant one bulb per pot in a good commercial potting soil allowing about an inch of space between the bulb and the pot. Leave about 1/3 of the bulb exposed. This bulb needs a well-lighted warm place in the beginning, then can be moved to a cooler, shaded space to make the blooms last longer.

Garden Tales

Just for the record, I've never really liked the term "forcing" – it sounds so violent. I prefer to use the word "coaxing." All bulbs want to flower – it's their nature. Sometimes I just want them to do it at a time when they normally wouldn't.

Part of my job at J&P is to supply plants to be used for catalog photography. Unfortunately, by the time the varieties for the catalog have been chosen, we often have no flowers in bloom to photograph. I always seem to be working on a schedule that's in direct opposition to nature. But I love a good challenge.

The greenhouse can be useful for growing roses and perennials, and bringing them into flower on my timetable. But bulbs are a different breed. First, they need a chilling period in order to bloom most effectively, so I have to plan way in advance. Bulbs in containers do not necessarily grow as they would in a garden, either.

The Amaryllis are a notable exception. They're amazing – there's almost nothing you can do to keep them from blooming! I've heard stories around here of bulbs blooming in desk drawers, on top of cabinets, in our compost area. My horticultural expertise is wasted on these bulbs, because anyone can bring these gorgeous plants into bloom. That's why I like them so much – they're practically foolproof.

They're also a tremendous value, since unlike many other bulbs, they will reliably bloom for years. They are a big part of our Holiday decorating around here, just for that reason. They're big, bright, cheerful, and very versatile. I heartily recommend you try them this year!