Bearded irises are about the easiest of garden plants to grow and will give good results with a minimum of care, but like all plants, the better the culture the more magnificent the display. The following instructions are easy to implement and should lead to beautiful iris blooms year after year.
WHEN TO PLANT
Bearded irises should be planted in July, August or September. It’s important that the roots get established before the end of your growing season. Plant your iris at least six (6) weeks before your first frost.
Bearded irises need at least a half day of sun. A full day of sun is better except in extremely hot climates. Make sure to provide the iris with good drainage. A raised bed or slope plantings are ideal places to plant iris.
Bearded irises do well in most well-drained garden soils. If you have heavy soil, adding humus, coarse sand or rice hulls will improve drainage. Creating raised beds is the easiest way to ensure proper drainage.
Your iris should be planted so the tops of the rhizomes are slightly exposed and the roots are spread out facing downwards in the soil. In very hot climates, covering the rhizome with about an inch of soil is advisable. Firm the soil around the rhizome and water in. A common mistake is planting the iris too deep. Make sure that you do not have any soil covering the fans (leaves). This will ensure proper planting depth.
Newly planted iris need moisture to encourage root growth; however, over-watering can encourage rot. After the new iris have been planted, water immediately. 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. Over-watering is a common error and can lead to disease. Reblooming irises need a touch more water than spring only bloomers. If reblooming iris do not receive moisture over a three (3) week period during the summer, they may not bloom in fall.
Specific fertilizer recommendations depend on your soil type. A 6-10-10 application is recommended about six (6) weeks before spring bloom and after fall planting. Reblooming iris should have an additional application of fertilizer immediately after the completion of spring bloom. Avoid high nitrogen fertilizers. Alfalfa pellets are extremely beneficial when incorporated into the soil around newly planted iris.