Dutch iris bulbs are planted in fall for late spring bloom. Unpack them as soon as they arrive and keep them cool, dry, and out of direct sun until planting day.
Planting
- Pick your spot. Choose a site with full sun to part shade and soil that drains freely; iris bulbs rot in soggy ground.
- Prep the bed. Loosen soil 8-10 inches deep and mix in compost, adding coarse sand or grit to heavy clay.
- Set the depth. Plant bulbs 4-5 inches deep with the pointed end facing up.
- Space for impact. Space bulbs 6-9 inches apart and plant in clusters of 10 or more rather than single rows.
- Water in. Backfill, firm the soil gently, and water once to settle the bulbs.
- Mulch lightly. Add 1-2 inches of mulch in colder zones to buffer winter temperature swings.
Watering
- Fall and spring. Keep soil evenly moist while roots and foliage are growing, about an inch of water per week including rainfall.
- After bloom. Taper off watering as foliage yellows so bulbs can rest dry through summer.
- Containers. Check pots more often, and always use a pot with drainage holes.
Feeding
- At planting. Work a balanced bulb fertilizer or bone meal into the planting hole.
- In spring. Feed once as shoots emerge with a low-nitrogen granular fertilizer, then stop after flowering.
Pruning & Aftercare
- Deadhead spent flowers. Snip off faded blooms to keep the planting tidy.
- Leave the leaves. Let foliage die back naturally so the bulb can recharge for next year.
- Cutting for vases. Cut stems when the bud is just cracking open for the longest vase life.
Containers & Overwintering
- Pot planting. Use a deep container with fresh potting mix, spacing bulbs about 3 inches apart.
- Cold zones. Move potted bulbs to an unheated garage or shed for winter chilling, keeping the mix barely moist.
- Warm zones. In zone 9, plant in the coolest, best-drained spot you have and treat the display as seasonal.