Plant of the Month for June, 2014

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Iris cristata 'Alba'

 (EYE-ris kris-TA-da)

General Information:

Iris are popular plants for the sunny garden, but what if you want to grow them in shade? Iris cristata ‘Alba’ fills that role very nicely. It grows best in part shade with a reasonable amount of moisture.

This plant is much smaller than your common garden iris, but it puts on a nice show early in the season, well before the bearded iris. It does not need to be dug up regularly, and so far I have not seen an iris borer on them.

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Iris cristata ‘Alba’ ; photo by Robert Pavlis

The normal colouration for Iris crista, the dwarf crested iris, is dark blue, light lilac, or lavender and the alba form is white with yellow falls. The white one really stands out in a shady area.

The crested iris can be a bit tricky to plant. Out of 4 attempts, 2 have survived. The good news is that once it takes hold, it is quite easy to grow and it spreads fairly quickly—for an iris! The iris likes moisture, but I think it is important that when you plant, you keep the rhizomes uncovered. If they are covered with soil they seem to rot. Once established, new rhizomes grow along the soil surface, fully exposed.

Life Cycle: perennial

Height: 15cm (0.5ft)

Bloom Time: May

Natural Range: Eastern USA

Habitat: calcareous soils, in rich wooded slopes and floodplain forests in dappled shade

Synonyms:  none


Light: part-shade or sun if given enough moisture

Soil: well drained

Water: even moisture

USDA Hardiness Zone: 3-9

Propagation: seed, division

Seedex availability (ORG&HPS annual Seed Exchange): rarely

Sow @ 4°C for 3 months, then place @ 20°C for 3 months.
Requires soaking. Place in warm water until seeds swell, usually 24-48 hours. Discard floaters and the water used for soaking. See
sow fresh or soak old seed; prechill 4 weeks or place outdoors over winter and bring indoors once germinated to avoid temperature shock; transplant at 4 leaves
Robert Pavlis