bearded Iris (Germanica)

Bearded Iris (Germanica)

Common name:  Bearded Iris               Wildlife:   Attracts butterflies and hummingbirds.

Genus:  Iris        Family:   Iridaceae        Species:  Iris

Type:  Rhizome, hardy perennial            Hardiness: Zones 3-7S/10W          Bloom Time:  Early summer

Exposure:   Full sun    Height:  24" - 36"              Spread: Grows in clumps

Description:  There are some 300 species in the genus Iris. The flowers have three large outer petals called “falls” and three inner upright petals called “standards.” The falls may have beards or crests. Bearded iris are so-called because they have soft hairs along the center of the falls. In crested iris, the hairs form a comb or ridge.

Cultivation:  Hardy, easy to grow. Irises require at least a half-day (6-8 hours) of direct sunlight. Some afternoon shade is beneficial in extremely hot climates, but in general irises do best in full sun. Iris will grow in deep shade, but probably not flower. Provide your irises with good drainage. Good air circulation is essential. Plant your rhizomes at or just barely below the surface of the ground. Irises should be planted so the tops of the rhizomes are visible and the roots are spread out facing downwards in the soil. Tamp the soil firmly to anchor the rhizomes until new roots begin to grow, and water well. It is a common mistake to plant Irises too deeply.

Fertilizer: The soil type for your area will determine your fertilizer needs. Superphosphate, or a well-balanced fertilizer with an N-P-K ratio of 10-10-10 or 5-10-10 are recommended. Avoid anything high in nitrogen as it encourages soft growth that is susceptible to disease. Provide a light application in early spring and again a month after bloom . Place fertilizer around rhizomes, not directly on them. Alfalfa pellets (without salt) are extremely beneficial when incorporated in the soil around newly planted irises. Do NOT use Feed and Weed preparations.

Soil and pH: Prefer fertile, neutral to slightly acidic, well-drained soil. Keep rhizomes exposed.  If covered with soil or crowded by other plants, they'll rot.  If you have heavy soil, adding humus - compost - or other organic material - will improve drainage. Gypsum is an excellent soil conditioner that can improve most clay soils. The ideal pH for irises is 6.8 (slightly acidic) but irises are quite tolerant of less-than-perfect soils. Lime may be added to acidic soils and sulfur may be added to alkaline soils.

Watering:  Newly planted rhizomes need moisture so their root systems develop. Once established, irises should be watered when the top three inches of soil dry out. The watering frequency will depend to a great extent on your environment. Over watering of Irises is a common mistake. After planting, water well and continue watering until the first good rain. If lack of rain persists, watering should be deep enough to penetrate the shallow root system. Less frequent deep watering is better than frequent shallow watering. 

Pests/Diseases:  Irisis are relatively pest and disease free. The most common pest is iris borer. Macronoctua onusta is a caterpillar, the larvae of a medium-sized, nondescript noctural brownish moth. In autumn the moths lay their eggs on old iris leaves and nearby debris. The eggs hatch out with warm weather in the spring. The tiny white caterpillars search out fresh iris leaves. Early damage is hard to detect but as the caterpillars grow they attack the edges of the center foliage making notches and leaving slimy frass. The borer will hollow out the rhizome. Crush them in the foliage with your fingers. Iris borers are proven cannibals with only one surviving in each iris by the time they are half-grown. They have to be dug out at this point and have grown to between one and two inches, are pinkish in appearance with dark brown heads. In late summer they leave the rhizome, enter the soil and becoming dark brown pupae. This dormant stage allows the caterpillar to transform into a moth in the autumn, when they emerge, mate and lay their eggs to start the process over. Garden sanitation and visual inspection of your plants is most important. Most pesticides are not effective, and in any case are banned in this garden except in extreme circumstances.

Propogation/Transplanting:  When clumps become congested or lose vitality, divide and replant sound rhizomes in fresh soil.  For best results, plant iris rhizomes in July, August or September. This is also the best time (plants are normally dormant during the heat of July and August) to divide and replant iris that have become overcrowded, usually after three to five years. It is important that the roots of newly planted irises be well established before the end of the growing season. Plant your iris at least four to six weeks before your first hard freeze or killing frost.

Notes/Gardening Tips:  Irises are perennials and require time to grow. New growth may be noticeable within 2-3 weeks and begins with a new center leaf in the fan. Depending upon the maturity of the rhizome and the geographical location, there may or may not be blooms the first spring. Do not trim iris leaves, as they carry on photosynthesis for next year's growth. Cut off brown tips and cut the flowering stalk down to the rhizome to discourage rot. Irises need at least half a day of sun and well-drained soil. Without enough sun, they won't bloom.