Tips on Growing Bearded Iris Bulbs

Bearded IrisBearded iris bulbs are wonderful exotic looking, long-lived flowering bulbs that bloom in the spring and grow eight to twenty four inches tall.

The flowers have six petal; Three upright petals (called standards) and three hanging petals (called falls).

These delightful flowers are called “bearded” because of a fuzzy line or beard runs down the middle of each fall.

They come in so many beautiful  colors like blue and yellow, bi-colors like purple and white, and even pastel colors like pink.  What’s not to love!

How to Grow Bearded Iris

  • Plant bearded iris bulbs in light shade to full sun.
  • Grow in fertile, well-drained, light loamy soil with a pH of 6 to 7 that has been amended with organic matter. Clay soil will need amending with pine bark and compost to keep rhizomes from being too wet.Tip: Manure is not recommended but can be used if well-rotted and incorporated to at least 6 inches deep into the bed. It’s best not to let it come into contact with the rhizome.
  • Bearded iris bulbs are hardy to zone 3. Some Louisiana iris even grow as far south as zone 10.
  • Iris are grown from divisions from thick, fleshy rhizomes (underground stems) that store food produced by the sword-shaped, semi-evergreen leaves.
  • Rhizomes grow best when planted at or slightly below the soil surface with feeder roots penetrating the soil below.
  • Offsets develop each year underground from the original rhizome producing a large fan of leaves and several flower stalks. Tip: Keep rhizomes firm and healthy by providing good drainage. Plant in raised bed of at least 6″ or add a gravel mix like Stalite to your soil when planting.
  • At planting, fertilize with a low-nitrogen fertilizer such as 5-10-10 incorporating per 50ft (1 1/2 oz per 10 ft)
  • Keep watered before flowering in spring.
  • Once flowers fade, cut back flower stalks to an inch or two above the rhizome.
  • Only fertilize if needed (if you have good green foliage, the plants will be fine). If you do fertilize, apply 1/2 cup of 5-10-10 fertilizer per iris clump after they flower around the rhizome (fertilizer may burn rhizome if applied directly).
  • Divide after 3 to 5 years usually 4 to 6 weeks after flowering or in the fall. (See below on how to divide)

Plant bearded iris bulbs July through September so roots may be    established before winter. Container grown iris may be planted in the spring.

You will need a well-drained prepared bed. Dig a shallow hole just large enough for the rhizome or clump of rhizomes. Next, form a mound of soil in the center so that the top of the rhizome is slightly above soil level. Spread the roots over the mound and fill in with soil. Water well after planting.


Dividing Bearded Iris

If you find that your iris is getting crowded or encroaching on their neighbors, you will want to divide them. As mentioned earlier, do this anytime but preferably 4 to 6 weeks after blooming.

Dig them up and cut the leaves to one-third their length. Wash off the soil and cut rhizomes apart so that each section has at least one healthy fan of leaves, and firm, white roots.

Older rhizomes of bearded iris bulbs should be discarded even, if they feel firm, because they will have little flowering ability.

We hope these tips on growing Bearded iris has been helpful. If you have more questions or would like us to plant some in your garden, please give us a call at 615-350-8030 or fill out the contact form here.


You may also like info on:

How to divide and transplant daffodils

Tips on Planting Crocus in Middle Tennessee

Tips on Planting Tulips in Middle Tennessee


5-Common-Landscaping-Mistakes-Homeowners-Make_-andHow-To-Prevent-Them2At Acer, we're planting the good life. For FREE estimates call 615-350-8030 x 17 or complete our short form online.

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By | 2017-10-17T17:09:46+00:00 February 26th, 2015|Bearded Iris, Perennial Plants, Spring Bulbs|

About the Author:

Julia is the Social Media Manager for Acer Landscape Services.