Most iris “bulbs” only need to go a few inches deep, but the exact depth depends on the type of iris you’re planting.

Quick Scoop

  • Dutch iris and other true bulb irises: plant about 4 inches (10 cm) deep, measured from the top of the bulb to soil surface.
  • Dwarf iris (Iris reticulata): plant a bit shallower, about 3–4 inches deep.
  • Bearded iris (rhizomes): these are not planted “deep” at all—the fleshy rhizome should be at or just barely below the soil surface, with the top exposed or covered by no more than about 1 inch of soil.
  • Other rhizome irises (Louisiana, Spuria, Siberian, Japanese): usually set about 1–2 inches deep, with Japanese slightly deeper.

If you bury iris bulbs or rhizomes too deep, they are much more likely to rot or stop flowering, especially in heavy, wet soil.

Simple rule of thumb

  • For true bulbs (like Dutch or dwarf iris): aim for a planting depth roughly three times the bulb’s height.
  • For bearded iris rhizomes: think “shallow and sun-kissed”—top of the rhizome visible or barely covered, never buried.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.