Choosing tulip bulbs in early Autumn, you should select those without blemishes, bruises, or soft spots. Remember that large flowers are produced by large bulbs. Some species can grow quite tall, requiring staking to keep them upright. If you want shorter species, try Tulipa batalinii and Tulipa humilis at only about 6 inches tall. If you want tulips indoors that put out a large blossom and come in many colors, then you should turn to Triumph tulips. They are quite easy to grow inside.
Your Tulip bulbs should be stored in a dark, cool location, approximately 35-45F, for 3-4 months. Ideally, you should keep them cooler for the first 4 weeks and then warmer for the last few weeks. Try putting them in the crisper in your fridge or an unheated shed. Do not keep them near either fruits or vegetables that might be ripening, since there will be ethylene gasses. Ethylene will destroy your Tulip bulbs.
Once your bulbs are ready, find a container that will allow for adequate drainage. Choose flower pots, wooden boxes, baskets, but not clay pots. Clay containers will suck the water out of the soil too thoroughly, drying the bulb out. The pot should have drainage holes. The ideal size is about 8 inches deep and 10 inches in diameter. Three bulbs can be planted together in this size of pot.
Remember that the better the drainage, the better you will avoid rot. Yet, you do not want your bulb to dry out. So choose a soil that drains well, but avoid the ceramic pots that sap water from your soil too quickly. Your soil should be a combination of potting soil, compost or manure, and sand, in three equal parts. Fill your container up with the mixture, leaving only 3 or 4 inches to the top. Lay the bulbs on top of the soil with the pointy side up and not touching each other at all. Be careful not to press the bulbs down. The roots must be able to easily penetrate the mixture as they grow. Turning the flat side toward the outside of the pot, the first leaves will end up growing out and over the edge. Fill the pot to the rim with more soil mixture, so the bulbs are covered and you can only see the tips peeping through.
The pots need to be kept in a cool, dark place. You can put them in your basement or garage, but make sure it is dark enough and cool enough (approximately 40-45F). Water very little, weekly, discarding any water in the bottom drainage tray.
As the leaves begin to show, in the form of young shoots of about 2 inches (in about 10-12 weeks), haul the pots out to a place with low light. The temperature should be a bit warmer than 50F, even as warm as 60F. Move the pots a little at a time toward a window with very bright sunlight, but not direct sun. If you will rotate the pots as you move them, the growth of the stems will be quite even. You should start to see the flowers after only 2 or 3 weeks.
Caring for forced tulips is quite similar to caring for any other indoor plants. Feel the soil to see if it is dry. Then water it. Tulips use a significant amount of water, so check the soil often. Keep your Tulips out of direct sunlight and away from any kinds of drafts. However, keep them as cool as you can in order to extend their time of blooming.
As far as humidity is concerned, Tulips require normal levels. Add fertilizer biweekly, diluted to half the potency. Maintain a pH between 6.0-7.0. Once the flowers of your Tulips are spent, you should not allow the foliage to die down into the soil. This will poison the bulb. So remove the bulbs before this happens. Allow them to dry on their own. Store them in a cool and airy place for planting the following season.
