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WHEN, WHERE AND HOW TO PLANT- Ideal planting time in this area would be July, August or September. Iris growing in pots can be planted at any time between March and mid-September. Later planted iris may not root well enough to become established in the in fall. Iris should receive a minimum of one half a day of sun, Full sun in this climate is fine. Iris require good drainage and planting on a slope or raised bed is ideal. Planting depth is important as the thick rhizomes should be exposed and the roots spread out and downward into the soil.  Space rhizomes 12-24 inches apart.  Firm soil and water well.

SOIL PREPARATION- Iris will thrive in almost any well-drained garden soil. Heavy soils that drain poorly should be amended with humus, coarse sand and gypsum to improve drainage. Iris grow best at a soil pH of 6.8 (a little acidic) but will tolerate a wide range. To change pH add lime to acidic soils or sulphur to alkaline soils.

WATERING AND FERTILIZER- New plantings need water until they become established. Except in drought conditions established plantings donít need watering, in fact over-watering is an error. If you do need to water, deep watering at long intervals is best for the plants. Iris in decent soils need little in the way of fertilizer. Use a fertilizer such as bone meal, super phosphate or a complete fertilizer low in nitrogen such as 5-10-10. Make a light application in early spring and a second three to four weeks after blooming.

CARE- To keep your iris healthy, keep them weeded and free of debris. It is especially important to clean out dead iris leaves at the end of the growing season and very early in spring. This will help keep prevent disease and destroy over-wintering borer eggs.  Cut bloom stems off close to the ground when flowering ends and remove any diseased leaves throughout the summer. Healthy leaves should not be cut off.

    After several years healthy iris may become so crowded that bloom size and number decreases. When this happens clumps should be thinned or divided. Thin old clumps by removing old rhizomes from the center, leave the more vigorous new growth undisturbed. To divide and replant iris dig up the whole clump and remove and replant only the large new rhizomes around the outer edges. This should be done in July, August or early September.

INSECTS AND DISEASE- Well grown irises have few problems. Two fungus diseases, rust and leaf spot can be controlled with hand picking of leaves and careful sanitation. If iris plantings are too large, or infestation is too severe, control should be able to be maintained by hand spraying with a fungicide containing Daconil. Add a few drops of detergent per gallon to the mixture to help it stick to the iris leaves. Iris borers can be kept in check with good sanitation but if a serious infestation occurs use a systemic insecticide. If soft rot develops in the infested rhizomes dug out the worst parts (disinfect tools after each time used with chlorine) and drench the beds with agricultural streptomycin.

Mays Greenhouse ©2010