How to Force Hyacinth Bulbs for Indoor Flowers
Dutch hyacinths are among the world’s most fragrant flowers. These spring-blooming bulbs flower at the same time as daffodils and tulips. They are a beautiful addition to any yard or garden, and the bulbs grow as well in containers as they do in garden beds.
Forcing is a technique that lets you bring plants into bloom weeks or even months before they would normally flower outdoors. Hyacinths are among the easiest bulbs to force. Read on to learn how you can enjoy having these colorful bulbs blooming on your windowsill this February and March.
WHY IT’S IMPORTANT TO PRE-CHILL THE BULBS
As with most other spring-blooming bulbs, hyacinths need to go through a period of cold weather (35-48°F) in order to bloom properly. Being exposed to wintery temperatures tells the embryonic flower inside the bulb that spring is coming and flower development should begin. If the bulbs are not exposed to the right amount of cold for the right amount of time, the flowers will not mature properly and may not emerge at all.
HOW TO CHILL THE BULBS
It’s possible to purchase pre-chilled hyacinth bulbs, but they’re not always easy to find. Chilling your own bulbs gives you more control over bloom time and also gives you many more choices for varieties.
You can chill your hyacinth bulbs either before or after you plant them. In both cases, the chilling period needs to last at least 13 weeks. During this time the bulbs need:
- Moist soil or humid air
- Consistent temperatures of 35 to 48°F
WHERE TO CHILL THE BULBS
If you live in growing zones 7 and 8, you may be able to plant your hyacinth bulbs in pots and then just leave them outdoors. Temperatures need to be above freezing, but below 50 degrees for 13 consecutive weeks.
In colder areas (zones 3-6), you need to find a place where the bulbs will be protected from extreme cold so they don’t freeze. Consider using an unheated basement, an attached garage or porch, or a greenhouse or cold frame.
Another option is to chill the bulbs in a refrigerator. Just make sure there’s no fruit stored in there at the same time, because the ethylene gas given off by ripening fruit will damage the embryonic flowers inside the bulbs.
WHEN TO PLANT HYACINTHS FOR FORCING
To get a continuous parade of spring color, choose several different varieties of hyacinths and plant a few bulbs each week between mid-October and mid-November. Bulbs planted in mid-October will bloom in February. Bulbs planted in mid-November will typically bloom in March or April.
HOW TO PLANT THE BULBS
You can combine hyacinths, tulips, daffodils, crocus and other bulbs in the same pot, but you’ll get better results if you plant just one type of bulb per container. Hyacinths look best in shallow, 4 to 6” deep pots. Make sure there’s a drainage hole on the bottom and use a high quality growing mix to encourage strong root growth.
Start by pouring some growing mix into a bucket. Add warm water and stir it around with your hands until moist, but not soggy. Put 2 to 3” inches of mix in the bottom of the container and set the bulbs on top, pointy-end up. Hyacinths look best when there’s about 1” of space between each bulb. Cover with more soil, until the tips are about an inch below the soil surface. Label the pots so you know which varieties are in them and then water thoroughly to settle the bulbs in place.
Move the planted bulbs to a cool, dark place. During the chilling period, the bulbs will develop roots, so it’s important to keep the soil lightly moist.
TIPS FOR BLOOM TIME
By the time the chilling period ends, the bulbs will be well rooted and starting to sprout. If you want to hold them back a few weeks, just keep them cool and dark. When the sprouts are 2” tall, move the pots to a cool window with indirect light. When the buds begin to show color, move the plants to a sunny window.
Once the flowers are open, keep the pots in a relatively cool location out of direct sunlight to extend the bloom time. If you want to arrange your hyacinths in a vase, feel free cut the stems just as you would do outdoors.
HOW TO CARE FOR THE BULBS AFTER THEY BLOOM
When hyacinth bulbs are planted in a garden, they will usually rebloom for several years. When they’re grown in pots, most people treat the bulbs as annuals and discard them after they flower.
If you’re interested in planting spring-blooming bulbs in containers for outdoor display, read: How to Grow Spring Bulbs in Containers.