The iris is named after the Greek goddess of the rainbow. It is tall and many different types and colors are available. It is rugged, reliable, and easy to grow. There are over 300 species in the genus Iris. Irises come in different sizes from six inches to four feet. The most common colors are in shades of lavender, purple, white and yellow. Most popular is the tall bearded iris which can be 2 to 3 feet in height.
These six-petaled flowers have three outer hanging petals (called “falls”) and three inner upright petals (called “standards”). Irises can be bearded or crested. Bearded iris refers to the soft hairs along the center of the falls and crested refers to the hairs forming a comb or ridge instead. Most Iris flower in the late spring to early summer but some can bloom again in the fall. Irises attract butterflies and humming birds and can be used for cut flowers. They are a companion to roses, peonies, and lilies in gardens.
Plant irises in late summer and early fall, when nighttime temps remain between 40 and 50 degrees Fahrenheit or above. Irises need full sun at least half the day. Some varieties will tolerate shade. Some may grow tall in the shade and not flower. Bearded irises must not be shaded out by other plants. They do best in a special bed of their own. Soil should be fertile, neutral to slightly acidic soil with good drainage. They will not tolerate wet soil in wintertime. Plant to a depth of about 4 inches. For more specific information regarding soil content check Growing Irises.
Deadhead (remove spent blooms) consistently. After blooming is finished, cut flower stems down at their base, but do NOT trim iris leaves after they have finished blooming. Leaves carry on photosynthesis and generate energy for next year’s growth. Cut off brown tips—and cut the flowering stalk down to the rhizome (root) to discourage rot. Taller irises may need staking or they will fall over.
Do not overwater irises. Too much moisture in the soil can cause the rhizomes to rot, but water consistently and deeply, especially during summer drought.
Keep rhizomes exposed. Unlike bulbs, which thrive deep underground, 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. Irises may benefit from shallow mulching in the spring.
Irises are deer-resistant and drought-tolerant. However, they are susceptible to the horrible Iris Borer which overwinters as eggs in spent leaves. If you see vertical streaks in the leaves, then look for these pests and squash them! If you see signs of rot in the rhizome, dig it up and remove the affected parts.
Iris are known to be toxic to pets, with the bulb being the most toxic part.
Irises can become overcrowded which causes the rhizomes to lose vitality and stop blooming. This can usually happens every 2 to 5 years and the plant will need to be divided. Divide irises after flowering finishes and then trim the foliage back to six inches.