How to Grow Iris:
- Irises should be planted in July, August, September. It is imperative that the roots of the newly planted iris be well-established before the growing season ends.
- Irises need at least half a day of sun. Be sure to provide good drainage, planting either on a slope or in raised beds. Ideal PH is 6.8 (slightly acidic).
- Irises should be planted so the tops of the rhizomes are exposed and the roots are spread out facing downward in the soil. Firm the soil around each rhizome and then water to help settle the soil. It is a common mistake to plant irises too deep.
- Irises should be planted 12 to 24 inches apart. Close planting will give an immediate effect, but will then need to be thinned often.
- Newly planted rhizomes need moisture to help their root systems become established. Deep watering at long intervals is always better than shallow watering. Once established, irises don’t commonly need to be watered. Overwatering is a common error.
- Fertilization recommendations depend on your soil type but bone meal, superphosphate and 6-10-10 are all effective. A light application in early spring and again about a month after bloom. Avoid using anything with high in nitrogen as nitrogen encourages rot problems.
- Iris need to be thinned and divided every 3-4 years. If Iris get too crowded the bloom will suffer. Old clumps may be thinned by removing the old divisions at the center of the clumps or you may dig up the entire clump and only replant the large new rhizomes.
- In general, keep your iris beds clean and free of weeds and debris. This will allow the rhizomes to bask in the sun. Cut old blooms after done blooming. Healthy green leaves should be left undisturbed but remove any diseased or brown leaves