Growing Dwarf Iris (Iris reticulata) Indoors: Forcing Miniature Iris Bulbs

Botanical Name: Iris reticulata

Imagine growing mini iris plants on your sunny windowsill in mid-winter. These petite flowers grow from bulbs (not rhizomes like many irises) and are easy to force in containers.

All irises are exquisite for their graceful form and symmetry, with 3 inner petals standing upright and 3 outer petals (falls).

Iris reticulata 'Harmony' (shown at right) is among the most popular dwarf varieties—and one of the most captivating flowers you can grow indoors or out. Those richly colored blooms are also sweetly scented.

How to Force Dwarf Iris Bulbs - Step by Step

These mini irises need a cold treatment for 8 weeks. Start in October or November for mid-winter blooms.

1. Choose a shallow pot (about 6 in / 15 cm deep) with drainage holes. Plant iris bulbs 2–3 inches (5–7.5 cm) deep. Crowd bulbs side by side, pointed end up.
2. Water thoroughly and empty drainage saucer.
3. Move pot to a dark, cool (35–45°F / 2–7°C), non-freezing location—basement, unheated garage, or refrigerator. Avoid storing near ripening fruit/vegetables (ethylene gas damages bulbs). Keep in cold storage ~8 weeks. Keep medium barely moist.
4. When shoots reach ~2 in (5 cm) tall, bring pot out of cold storage into a warmer (60°F / 16°C) location with at least 4 hours of sunlight daily. Give the pot a quarter turn daily for even growth. When in full bloom, keep irises in a sunny location.

Your beautiful iris plants should burst into bloom in about 2 weeks. Make them last longer by keeping flowers as cool as possible. Even with cool temps, flowers last only 5–10 days.

Tips for Growing Iris Plants Indoors Quick Reference

Origin: High mountains of Iran and Turkey

Height: 6–10 in (15–25 cm)

Light: Dark during cold treatment (cover pot if needed). After shoots appear, move to bright light with some direct sun.

Water: Water sparingly until growth appears, then keep soil evenly moist. Soggy soil rots bulbs.

Humidity: Average room humidity

Temperature: After cold treatment, cool to average 60–65°F (10–18°C). If too chilly for you, find a cool windowsill or sun porch.

Soil: Any good potting mix

Fertilizer: Feed monthly with balanced liquid fertilizer diluted by half from planting until blooming starts. Don't fertilize during bloom.

Propagation: Bulbs. Irises can't be forced a second time indoors. If keeping, allow foliage to die back naturally, cut off stems, store bulbs cool and dry. Plant in sunny, well-drained garden spot in fall. Dwarf iris hardy to Zone 5, naturally blooms early spring.