Plant your Tall Bearded Iris
How deep should I plant my iris?
Iris will grow in any good neutral garden soil. If your other plants do well in your garden, so will your iris. If you have heavy loam or clay soil it may help to mix in some coarse pebbles or sand where you intend to plant. Important: clay and sand make concrete, so go easy on the sand when mixing it in with your compost.
Never plant too deep. Remember, iris aren't bulbs like tulips and daffodils. Plant them 6 inches deep and you might as well kiss them goodbye. Roots down and well spread, plant the rhizome so that it is half buried, half exposed. You should still be able to see the top of your rhizome. In Colorado we plant them just below the surface of the ground to protect them from our glorious sunshine. At a mile high, they have a good chance of getting sun-scald --unless you use a SPF 30 sun screen or higher prior to planting. (Just Kidding)
The best time to plant iris is between July and September to allow new root growth before winter and to avoid extreme temperatures.