Description
The tall, beautiful iris, named after the Greek goddess who rode rainbows, comes in many magical colors. Despite its divine origins, this beautiful flower is rugged, reliable, and easy to grow. Learn to plant and care for irises for long-term success.
More than 250 species make up the genus Iris. The most familiar irises are the tall bearded irises (Iris germanica), which reach 2 to 3 feet in height. Their distinctive six-petaled flowers have three outer hanging petals (called “falls”) and three inner upright petals (called “standards”).
Irises may be a bearded or crested (aka “beardless”) type. Bearded iris are so-called because they have soft hairs along the center of their falls. The hairs on crested types, like the Siberian iris, form a comb or ridge instead.
Most irises flower from late spring to early summer. Some—mostly bearded hybrids—are remontant, meaning they may flower again later in the summer. The blooming period of Siberian irises tends to follow that of the bearded types.
Irises attract butterflies and hummingbirds, and make lovely cut flowers. For iris companions in the garden, look to roses, peonies, and lilies.
How to Grow and Care for Irises Black
In the early spring, remove winter mulch and any old foliage to allow for fresh, new growth.
Fertilize in early spring, scratching an all-purpose fertilizer around the plants. Avoid high-nitrogen fertilizers. Reblooming irises perform best if fertilized again after the first wave of flowering is finished.
Do not overwater irises; too much moisture in the soil can cause the rhizomes to rot. Water consistently and deeply, especially during summer drought.
Keep rhizomes exposed. Unlike bulbs, which thrive deep underground, bearded iris rhizomes need a bit of sun and air to dry them out. If they’re covered with soil or crowded by other plants, they’ll rot.
Taller irises may need staking, or they will fall over.
Deadhead (remove spent blooms) consistently. Bearded Irises flower sequentially on buds spaced along the stems.
After blooming is finished, cut flower stems down to their base to discourage rhizome rot, but do NOT trim the iris’ leaves. The plant’s foliage carries on with photosynthesis and generates energy for next year’s growth and flowers. Only prune off brown leaf tips, if desired.
After a hard frost in the fall, cut foliage back hard, remove any foliage that appears spotted or yellowed, and dispose of all debris in the trash.
If iris foliage is hit with heavy frost, remove and destroy it to eliminate borer eggs. See your local frost dates.
For winter protection, cover the rhizomes with an inch or two of sand topped with a light layer of evergreen boughs, applied after the ground freezes and removed when the forsythias bloom in the following spring.
Iris borer, a common iris pest, overwinters as eggs in spent leaves. Signs include vertical streaks in the leaves. If apparent, look for the pests and squash them! If you see rot in the rhizome, dig it up and remove the affected parts. See pest tips below.
Dividing Irises
Over time, it’s not unusual for plantings of irises to become overcrowded, which causes the rhizomes to lose vitality and stop blooming. When this happens (usually every 2 to 5 years), it’s time to divide and replant healthy rhizomes in fresh soil.
When to divide? Do this task after flowering finishes, and then trim the foliage back to six inches.
Shortly after blooming (usually around midsummer), carefully dig up (lift) the clump of irises. You’ll find that the original rhizome that you planted (the “mother”) has produced several offshoot rhizomes.
Separate these rhizomes from the mother with a sharp knife and discard the mother, as it will no longer produce blooms.
Inspect the rhizomes for any rotting tissue, soft spots, or other signs of disease, removing and discarding infected parts or entire unhealthy rhizomes.
Plant these fresh rhizomes in a new bed, replant them where they were before (after adding new soil), or share them with friends and spread the joy of irises!