Crocus flowers are among the first to herald spring, sometimes popping their bright blooms through the snow. Fortunately, we don’t have to wait till spring to enjoy these glorious flowers. Growing crocus indoors is easy to do by forcing them into bloom mid-winter. Start the process in fall — October is an ideal time. A crocus bulb is actually a corm. Corms produce beautiful cup-shaped blooms in purple, lavender, white or yellow — plain or striped — each with a bright orange stigma. All have slender, upright leaves that are green and white striped.
Crocuses need a cold treatment for 12 weeks to bloom. If you bought pre-chilled corms, you can skip this step.
- Choose a shallow pot (at least 3 in/7 cm deep) with drainage holes in the bottom. Fill the pot loosely with potting mix. Set several corms side by side — close but not touching — pointed end up. Set corms so that their tips are even with pot rim. Do not press the corms into the mix. It should be loose so the roots can grow through it easily. Cover with additional potting mix until just barely covered.
- Water thoroughly and discard drainage.
- Move pot to a dark, cool, but not freezing, (40°F/4°C) location such as a basement, unheated garage or refrigerator. Avoid storing corms near ripening fruit or vegetables which give off ethylene gas which can damage the corms. Keep them in cold storage for about 12 weeks. Keep the medium barely moist.
- When shoots reach about 2 in (5 cm) tall, bring the pot out of cold storage and place it in a slightly warmer (50°F/10°C) location with low light intensity. Over the next few days, gradually move it toward a sunny window. Turn the pot every day for even growth. When in full bloom, keep crocuses in a bright location out of direct sun to prolong the bloom.
Crocus Care Tips
Origin: Hybrids with corms originating from Europe, North Africa and Asia
Height: Up to 8 in (20 cm)
Light: Keep in a dark location during cold treatment. Cover pot with a box, pot or black garbage bag if necessary. After shoots appear, move to bright light with some direct sun as directed above.
Water: Water sparingly until growth appears, then water enough to keep soil evenly moist. Flowering plants are thirsty, so check them often.
Humidity: Average room humidity.
Temperature: Cool to average (40-60°F/6-16°C)
Soil: Any good potting mix.
Fertilizer: Feed monthly with a balanced liquid fertilizer diluted by half from planting until start of blooming. Do not fertilize while plants are in bloom.
Propagation: Corms will not bloom a second time indoors. They do produce offsets, but they take a few years to mature. If you want to keep them, allow the foliage to die back naturally, then store them in a cool, dry place. Plant the corms in your flower garden in the fall and let Mother Nature take care of them. They’ll bloom when they’re ready.