Iris is a genus of 310 species and is in the plant family Iridaceae that also included gladiolus, crocus and freesia. The plants are all perennial and grow from rhizomes or bulbs. The iris with rhizomes have 2-10 sword shaped leaves that grow in dense clumps while the iris with bulbs have 2-10 narrow leaves. The flowers appear on a long erect stems that may be branched. The flowers consist of three outer sepals called falls that usually are spreading or droop downward, and three inner petals called standards, that are upright. The standards may be delicate or large and showy and the falls may have various attractive and distinctive markings including a patch of yellow or white, known as a signal, or a row of hairs known as a beard. Petals and sepals may be lavender, blue, purple, white, pink, red, yellow, brown and combinations of these that resemble a rainbow.
Iris can grow in a variety of soil types from dry to wet and some grow in shallow water. Bulbus iris prefer drier soil than rhizomatous iris and both grow well in full sun to partial shade. The bloom time various greatly and with careful planning it is possible to have some species of iris blooming from mid spring to mid summer.
The genus name, Iris, honors the Greek goddess Iris whose name, ἶρις (îris) means rainbow and may refer to the wide variety of flower color.
Photo Credit Dcrjsr, Wikimedia Commons
Wildflowers: Iris Native to the Mid-Atlantic States
The environmental conditions of the Mid-Atlantic have resulted at least five species of native iris there but they may be native to other regions too. The iris described here are native to at least two states in the Mid-Atlantic.
Crested iris (Iris cristata)
Native to New York, Pennsylvania, and Maryland as well as to places in the Southwest, Midwest, Southeast, and New England, crested iris grows on rocky hillsides, in ravines, on mountain ledges, and along streams. Also known as short-stemmed iris, Lamance iris, or leafy blue flag it can be used as a groundcover and is useful in shade and rock gardens.
Height: 4-9″
Bloom Time: April-May
Bloom Color: Blue, pale blue, lavender, purple, lilac, and rarely white or pink
Light: Part shade but tolerates full sun
Soil: Average to fertile, high to medium moist, well-drained
USDA Hardiness Zones: 3-9
Photo Credit: Eric Hunt, Wikimedia Commons
Slender Blue Flag (Iris prismatica)
Also known as cubeseed iris, slender blue flag is native to New York, Pennsylvania, New Jersey, and Maryland as well as places in the Southeast and New England. It grows in bogs and marshes and along streams and tolerates salty conditions, summer drought, occasional flooding and deer, but attracts birds including hummingbirds. It is a good choice for use along streams and ponds as well as in seaside, bog, bird, and wildlife gardens.
Height: 1-3′
Bloom Time: Late spring to mid summer
Bloom Color: Pale blue to blue violet with white blotch
Light: Full sun to part shade
Soil: Average, moist to wet, neutral to slightly acidic
USDA Hardiness Zones: 3-9
Photo Credit: Masebrock, Wikimedia Commons
Dwarf Violet Iris (Iris verna)
Native to Pennsylvania and Maryland as well as places in the Midwest and Southeast, this dwarf iris grows in nutrient-poor acidic soils in open to semi-shaded woodlands. It’s flowers are 1-2″ across, intensely fragrant, and appear before the foliage. Also known as dwarf iris and vernal iris, it is a good choice for rock, shade, woodland, and fragrance gardens.
Height: 2-3″
Bloom Time: Spring
Bloom Color: Light to deep blue or violet, rarely white; falls with yellow signals
Light: Partial sun but tolerates full sun
Soil: Average, dry to moist, well-drained, neutral to acid
USDA Hardiness Zones: 5-9
Photo Credit: Eric Hunt, Wikimedia Commons
Blue flag Iris (Iris versicolor )
Blue flag iris is native to New York, New Jersey and Maryland as well as places in the Rocky Mountain area, Midwest, Southeast and New England. It grows in sedge meadows, marshes, and along stream banks and shores. Also known as harlequin blue flag, larger blue flag, northern blue flag, and poison flag it tolerates occasional flooding and can be grown in 4″ of water.
Height: 2-3′
Bloom Time: May to June
Bloom Color: Light to deep blue and purple
Light: Full; tolerates partial shade
Soil: Average, moist to wet,
USDA Hardiness Zones: 3-6
Photo Credit: D. Gordon E. Robertson, Wikimedia Commons
Virginia Iris (Iris virginica )
Also called southern blue flag, Virginia iris is native to New York, Pennsylvania and Maryland as well as places in the Southeast, Midwest, and Southwest. It grows in wet areas, such as marshes, wet meadows, swamps, river bottoms and is an excellent choice for a pond margin, water garden or rain garden.
Height: 2-3′
Bloom Time: May to July
Bloom Color: Light blue to deep violet, rarely white
Light: Full sun
Soil: Humusy to sandy, moist to very wet, acidic
USDA Hardiness Zones: 5-9
Photo Credit: Eric Hunt, Wikimedia Commons
The Middle Atlantic region includes Delaware, Maryland, New Jersey, New York, Pennsylvania, and the District of Columbia. The region is characterized by cold winters and hot summers, high humidity in summer along some areas of the coast, and precipitation between 32 and 52″ per year.