How to Grow: Iris

Learn about iris, including how to plant and grow them.

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podcast transcript

Flower, Iris, Wild Flower, Purple, Flowers, Meadow

How to Grow: Iris

Iris spp and hybrids

Other Name

Many different types


Sun Requirements

full sun, part sun


Bloom Period and Seasonal Color

Spring to early summer in colors such as black, white, blue, peach, pink, yellow, red, and purple.


Mature Height x Spread

8 to 36 inches x 1 to 2 feet


Added Benefits

Attracts beneficials, deer resistant


Iris is a diverse group of plants that add color and splendor to spring and early summer gardens. This is an easy to grow group of plants and there are many different species of iris that grow well throughout New England. The most common are the bearded iris, Siberian iris (Iris siberica) and Japanese iris (Iris ensata). There are also fall planted iris bulbs (Iris reticulata) that bloom in spring and are grown similar to daffodils and tulips. The perennial flower iris produce strong flower stalks with beautifully colored flowers that are standards in cottage gardens and are a good cut flower. The leaves are sword-like and flat. They remain an attraction even after the flowers fade. Some varieties even rebloom again in late summer.


Where, When and How to Plant

Siberian and Japanese iris grow in clumps from root systems similar to other perennials. Bearded iris grows from under grown rhizomes. Plant bearded iris rhizomes, or Siberian and Japanese iris plants, from a local garden center or divisions from a gardening friend, from spring to late summer. Iris grow best in full or part sun, in well drained, compost amended soil. Siberian and Japanese iris grow better in wetter soil conditions than bearded iris. Plant bearded iris rhizomes so they’re barely covered with soil. Space plants 1 to 2 feet apart.


Growing Tips

Keep young plants well watered and mulch to keep the sol moist all summer. Fertilize each spring with compost.


Regional Advice and Care

All three of these iris types will need dividing every 3 to 4 years. Divide iris when they start flowering less and the centers of clumps start to die. Cut back the foliage to 6 inches tall in late summer. To divide Siberian and Japanese iris, dig up the entire plant, divide the clumps and reset them in compost-amended soil. For bearded iris, dig up the rhizomes inspect them for damage and holes. The iris borer insect causes the holes. Discard any soft, rotting rhizomes due to these holes to reduce the borer infestation. Replant in compost amended soil, spacing the rhizomes about 1 foot apart.


Companion Planting and Design

Iris grows well in a flower border with other spring blooming perennials such as peonies and catmint. Grow Japanese or Siberia iris in a perennial flower garden or near a pond or wet area. They grow well in moist conditions. Grow bulb iris in a rock garden or a low perennial border with other spring flowering bulbs and perennials.


Try These

For bearded iris hybrids, try “Beverly Sills” (peach), “Batik” (blue and white freckled), “Apollo” (yellow and white), and “Edith Wolford” (blue and white). “Immortality” is a white, reblooming bearded iris. Some nice Siberian iris varieties include “Caesar’s Brother” (blue), “Butter and Sugar” (white and yellow), and “Gull’s Wings” (white). Some good Japanese varieties are “Great White Heron” and “Blue Pompom”.

Excerpted from my book, New England Getting Started Garden Guide.

Podcast Transcript

Iris, Flower, Garden, Purple, Flora, Plant, SpringThe Greek Goddess of Rainbows is named after this plant. Vincent Van Gough and Georgia O’Keefe loved to paint it, and poets Mary Oliver and Robert Frost wrote about it. What flower is this? The Iris. There are hundreds of iris species growing around the world. It’s a common symbol in Western culture and is the flower in the French fleur de lis. While most gardeners are familiar with the popular German bearded iris, lesser know iris species offer some interesting variations.

Siberian Iris grow in clumps that are virtually pest free. The Japanese iris has flowers that look like butterflies floating on the stems and thrives in moist, acidic soils. And reblooming bearded iris, such as Immortality, offer iris lovers a second flush of flowers in late summer.

Most iris are easy to grow – just divide them every three or four years when you notice fewer flowers and the plants are overcrowded. One threat to bearded Iris is the borer insect. It tunnels through the leaves to the roots – called rhizomes – leaving yellow streaks. Cut off and destroy infected leaves, clean up the foliage in the fall, and remove any rhizomes with holes in them.

For this week’s tip, pinch off the first blossoms of your sweet peppers to get a better overall crop. By removing the first flowers on newly transplanted peppers, the plant will send more energy into growing a bigger plant that will produce more fruit this summer.

From the Vermont Garden Journal on Vermont Public Radio.

Go here for a video on how to divide perennials

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