German Bearded Iris Rhizomes

How To Grow and Care for Bearded Irises

Bearded iris bulbs, or rhizomes, should be planted in late summer or fall with plenty of time for rooting before cold weather arrives, though they can also be planted in the spring. Plant horizontal rhizomes so that the top 1⁄3- 1⁄2 is above the soil level (too deep and you're likely to see rot) and in loamy, well-draining soil. Be sure to space bearded iris bulbs 12-24" apart. A slope or raised bed is best. German iris prefers lots of sun, but if you're in a hotter climate, try to plant where sun exposure is 4 to 6 hours, with shade the rest of the day.

Your German bearded iris flower will begin blooming in early May for most areas of the US and will continue through mid-June, depending on the climate. For care, water generously right after planting and infrequently once established. Fertilize bearded irises with a high phosphorus fertilizer every few years. After the flowers have faded, cut back the flowering stem and trim the foliage into a fan shape about 12" tall. German iris flowers grows 30-36" tall and are hardy in zones 4-10.

Read our iris care guide to learn how to plant and grow irises.

Dividing Bearded Irises

Most bearded iris need to be divided every 3-5 years. These are the steps to take to divide iris rhizomes:

1. Bearded irises should be pruned in late summer or early fall when the foliage starts to fall over (if this has not been done earlier). With a sharp knife, cut the foliage 8-10" above the soil level. Trim bearded irises into a fan shape.
2. Carefully dig up the old clumps. Divide bearded irises with a sharp knife. To avoid spreading disease, dip the knife in rubbing alcohol or a 20% solution of household bleach between each cut. Discard the oldest (center) part of the rhizome. Check for evidence of disease or borers. Destroy (do not compost) any infested rhizomes.
3. Make sure each new division has a strong root section and a single fan of leaves. Dust the cut surface with powdered sulfur and allow it to dry for 1-2 days. The sulfur acts as a fungicide and helps avoid problems with disease and pests.
4. Replant the horizontal rhizome with the top 1 ⁄3- 1 ⁄2 of the rhizome showing above the soil. Plant bearded irises with the fan of the leaves pointing in the direction you want the plant to grow.

FAQ - Bearded Irises

When Do Bearded Irises Bloom?

Bearded irises typically bloom in late spring to early summer, depending on the climate and variety. Some varieties, known as reblooming iris, can bloom again in the late summer or early fall.

Where To Plant Bearded Irises

Bearded irises should be planted in a location that receives full sun, with at least 6 hours of direct sunlight per day. They prefer well-draining soil and should be planted with the rhizome slightly exposed to prevent rot.

How Tall Do Bearded Irises Grow?

Bearded irises can grow to varying heights, typically ranging from 8 inches for dwarf varieties to up to 40 inches for tall bearded irises, depending on the specific variety and growing conditions.