Forcing Dutch Iris Bulbs Indoors: Step-by-Step Guide to Winter Blooms

Botanical Name: Iridaceae x hollandica

Dutch iris bulbs demand two things to grow and bloom well: sunshine and good drainage. If you have a sunny window, you can easily grow these magnificent flowers at home.

Unlike most irises, Dutch irises grow from bulbs, not rhizomes, making them excellent for forcing.

Tall, upright stems and silky, delicate blooms lend elegant beauty wherever displayed. Flowers grow up to 4 inches (10 cm) across in a rich rainbow of colors—blue, violet, white, yellow, and bicolors.

How to Force Dutch Iris Bulbs - Step by Step

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

1. Choose a shallow pot (at least 3 in / 7 cm deep) with drainage holes. Fill loosely with potting mix. Set several bulbs side by side—close but not touching—pointed end up. Set bulbs so tips are even with pot rim. Top with additional mix until just barely covered.


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 low light. Over several days, gradually move toward a sunny window. Turn pot daily for even growth. When in full bloom, keep irises in a sunny location.

Dutch Iris Care Quick Reference

Origin: Bred in the Netherlands; cross between Spanish and African irises

Height: Up to 24 in (60 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)

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: Irises can't be forced a second time indoors. If keeping, allow foliage to die back naturally, store in cool, dry place. Plant bulbs in sunny garden spot in fall. Dutch irises are hardy to Zone 5 and naturally bloom in early summer. Bulbs multiply rapidly for a profusion of captivating irises.