Iris bulbs, specifically Dutch Iris bulbs, should be planted in holes about 4 inches (10 cm) deep and spaced 2 to 4 inches apart. The bulbs should be planted with the pointed tip facing upwards, in well-drained soil, ideally in a sunny location. For bearded iris (which grows from rhizomes rather than bulbs), the rhizomes should be planted shallowly with the top part just showing at the soil surface rather than buried deeply. Siberian irises are planted with the junction point between the roots and fan about 1 to 2 inches below soil level, in holes 3 to 5 inches deep. Summary:
- Dutch Iris bulbs: 4 inches (10 cm) deep, 2 to 4 inches apart.
- Bearded Iris rhizomes: just at soil surface, tops showing.
- Siberian Iris: 3 to 5 inches deep, junction 1 to 2 inches below soil.
- Plant bulbs with pointed tip upwards, firm soil around them, and water well after planting.
This planting depth helps ensure healthy growth and blooming by avoiding planting too deep or too shallow, which can either prevent flowering or expose the bulbs/rhizomes to elements or rot.
