When to Plant

For best results, Iris should be planted in July, August or September. It's imperative that the roots of newly planted Iris be well-established before the growing season ends. In areas of hot summers and mild winters, September or October planting may be preferred.

Where to Plant

Iris need at least a half day of sun. In extremely hot climates some shade is beneficial, but in most climates Iris do best in full sun. Be sure to provide your Iris with good drainage, planting either on a slope or in raised beds.

Soil Preparation

Iris will thrive in most well-drained garden soils. Planting on a slope or in a raised bed helps ensure good drainage. If your soil is heavy, add coarse sand or humus to improve drainage. Gypsum is an excellent soil conditioner that can improve most clay soils.

The ideal soil pH is 6.8 (slightly acid), but Iris are tolerant in this regard. To adjust the pH of your soil, lime may be added to acidic soils or sulfur to alkaline soils. It is always best to have your soil analyzed before taking corrective measures.

Depth to Plant

Iris should be planted so the tops of the rhizomes are exposed and the roots are spread out, facing downward in the soil. In very light soils or in extremely hot climates, covering the rhizome with one inch of soil may be desirable. Firm the soil around each rhizome and then water to help settle the soil. A common mistake is to plant Iris too deeply.

Distance Apart

Iris are generally planted 12 to 24 inches apart. Close planting gives an immediate effect, but closely planted Iris will need to be thinned often. Plants spaced further apart will need less frequent thinning.

Watering

Newly set plants need moisture to help their root systems become established. Specific watering information depends on your climate and your soil type, but keep in mind that deep watering at long intervals is better than more frequent shallow waterings. Once established, Iris normally don't need to be watered except in arid areas. Overwatering is a common error.

Fertilization

Specific fertilizer recommendations depend on your soil type, but bone meal, superphosphate and 6-10-10 are all effective. A light application about a month after bloom will reward you with good growth and bloom. Avoid using anything high in nitrogen, as nitrogen encourages rot problems.

Thinning Old Clumps

Iris need to be thinned or divided before they become overcrowded, generally every 3-4 years. If Iris are allowed to become very crowded, the bloom will suffer. Some varieties may crowd others out and disease problems may be aggravated.

Old clumps may be thinned by removing the old rhizomes at the centers of the clumps and leaving new growth in the ground. Or, you may dig up the entire clump and remove and replant the large new rhizomes.

General Garden Care

Keep your Iris beds clean and free of weeds and debris, allowing the tops of the rhizomes to bask in the sun. Bloom stems should be cut off close to the ground after blooming. Healthy green leaves should be left undisturbed, but diseased or brown leaves should be removed.

Dwarf Bearded: These miniature gems display their splendid bloom early in the spring. Ranging in height from 5 to15 inches, these delightful Iris are perfectly suited for edgings, borders or rock gardens.

Intermediate Bearded: Blooming after the Dwarfs and reaching a height of 16 to 28 inches, these cheerful Iris will brighten your garden and mix well with other favorite spring bloomers.

Tall Bearded: These are the gorgeous queens of the Iris world, with magnificent 6 inch blooms displayed on stems over 29 inches high. The later-blooming flowers are available in every color of the spectrum and include an incredible variety of color patterns and combinations.