How to Force Tulips to Bloom Indoors in Winter

Instructions for Making Bulbs Grow Indoors During the Cold Season

May 16, 2009

Tulips can be forced to bloom indoors in pots during the winter by tricking them into reacting as though spring has arrived.

To enjoy beautiful potted tulip blooms in the winter, purchase high quality bulbs from a garden center or order bulbs from a reputable company and then follow these steps for preparing and planting them.

Purchase Tulip Varieties That Respond Well to Forcing

Some tulip varieties are more amenable to being tricked into winter growth than others. Good choices include:

If purchasing bulbs from a garden center, select heavy, blemish-free bulbs that are not soft and show no signs of mold. Plant bulbs no later than early October.

Plant Tulip Bulbs for Indoor Winter Blooming

Use clean flowerpots and add 2 inches or more of moistened peat moss combined with perlite or vermiculite to the bottom of the pot for drainage. Enough of this mix should be added so that bulbs will be planted near the top of the pot.

Add the bulbs with roots facing downward (pointy side up) and then cover them with soil. Bulbs should be planted shallowly, so that their tips stick out of the soil.

Bulbs for indoor blooms can be planted far closer together than outdoor tulips – they can be almost touching one another. After planting, soak the soil until water seeps out of the flowerpot’s drainage holes.

Simulate Winter to Force Early Blooming

Potted tulip bulbs should be moved to a dark place where the temperature ranges between 35 and 48 degrees Fahrenheit. Possibilities include basements, unheated garages, refrigerators, or outdoors if it’s cold enough. Bulbs must not be allowed to freeze, however, and they should not be stored near ripening fruit, which gives of ethylene gas that can inhibit flowering later on.

Place a cardboard box or paper bag over the flowerpots to keep them in the dark and retain soil moisture. Check soil from time to time and add enough water to keep it slightly moist but not soaked.

Chill bulbs for 10-12 weeks if the temperature is closer to 41 degrees Fahrenheit and 14-16 weeks if it's closer to 48 degrees. There are a few varieties such as Brilliant Star that require only 10 weeks of chilling at 48 degrees and bloom earlier than other varieties, but most tulips need more chilling time.

Simulate Spring for Winter Tulip Blooms

Once the chilling period is complete, check the flowerpot drainage holes to ensure that roots have developed. When roots are visible and shoots are about an inch high, move pots to a bright sunny spot to induce blooming.

To have blooms for the entire season, plant batches of bulbs at intervals so that they can be removed from the chilling spot and encouraged to bloom at different times.