Growing Iris's
TIPS FOR IRIS GROWERS
Divide clumps of bearded iris every 3 to 5 years for best bloom; remember they like good drainage and plenty of sun. Clean up and burn dead bearded iris leaves in the fall or spring to help control iris border. Plant plenty of yellows and blues for best visual results. Lavenders add sparkle! There are many shorter growing iris to choose from, including early blooming dwarfs such as dwarf bearded (Iris pumila), arctic (I. setosa), beardless Japanese (I. ensata) and Siberian iris (I. sibirica). Irises do not require frequent division; many beardless irises also do well in moist spots.
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. Iris are also available as potted plants in the perennial lot, and these can be planted in spring, summer or fall.
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 well-drained garden soil. Planting on a slope or in raised beds helps ensure good drainage. If your soil is heavy, coarse sand may be added to improve drainage. Gypsum is an excellent soil conditioner that can improve most clay soils. The ideal pH is 6.8 (slightly acidic), but iris are tolerant in this respect. To lower the pH of your soil, sulphur may be added to alkaline soils.
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 1 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, but keep in mind that deep watering at long intervals is better than more frequent shallow watering. Once established, iris normally don’t need to be watered except in arid areas. Over watering is a common error.
Fertilization
Specific fertilizer recommendations depend on your soil type, but bone meal, superphosphate and10-52-10 are all effective. A light application in the early spring and a second 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 over-crowded, generally every 3-4 years. If iris are allowed to become too 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 divisions 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.
