Dwarf Iris Planting Guide

Tiny, but mighty, dwarf irises add pops of color, intricate patterns and accents with bright yellow or gold blazes, speckled and spotted. These short beauties are perfect for edging the walk by the front door or adding some color to the patio border where you’ll enjoy that first early season lunch outdoors in the sunshine.

Choosing a Planting Site

Choose a site with full to half day sun. Since dwarf irises actively grow in the spring and then slip into dormancy by May, areas near/under open-branched or limbed up deciduous trees can work beautifully. These spots are often sunny and perfect early in the spring, before the trees are fully leafed out. In warmer regions, a little protection from afternoon sun will extend the blooming window.

Soil Prep for Dwarf Irises

Look for a site that drains well. Irises are happy in average garden soil, and as with most bulbs, good drainage is important to avoid bulb rot. If your soil is heavy (clay or compacted) consider digging in a few generous handfuls of soil amendments such as a mix of course sand and compost, leaf mold or well-rotten manure. (Your local cooperative extension office can recommend good mixes that are appropriate for your local soil conditions.) A slow release granular fertilizer (10-10-10) mixed into the planting soil according to package directions can be helpful if you soil is lean. Note: we do not recommend using bone meal as it encourages pets and pests to dig up the bulbs you just planted.

When to Plant Dwarf Irises

Plant these bulbs in mid to late autumn or into early winter in mild regions, when soil in your area has started to cool. The roots on these iris bulbs start to develop in the fall and continue to grow, albeit more slowly, when soils are quite chilly but not yet frozen.

These bulbs should not be held over for spring planting as they need to develop a network of roots before spring sprouting begins.

How to Plant Dwarf Iris Bulbs

Dig holes 4-5” deep and add a handful or two of compost to the soil you removed. Plant your irises so the bulb base is 3” to 4” below the soil line. Put the bulb in the hole with the pointed end facing up, fill the hole with soil, pat to eliminate air pockets, and water well to settle the soil around the bulb. While there won’t be any visible growth in the fall, the bulbs' roots will be growing and creating a network for absorbing nutrients and moisture.

Because of their size, dwarf iris look best grouped, typically in clusters of about 6 per square foot.

During the Spring Growing Season

Dwarf irises need about one inch of water a week from rain, irrigation or a combination of the two.

When spring flowering has finished, don’t remove the leaves; they’re working to produce food for the bulbs. Allow the foliage ripen until it yellows before removing it.

At Season’s End

After flowering, your iris foliage will photosynthesize and create food for next year’s show. Then the bulbs will go dormant and sleep through the summer. They don’t need, or benefit from, any extra moisture during the summer. When fall temperatures cool, the bulbs will develop new roots and then wait for spring rains and warmth to prompt the next cycle of growth and blooms.

Forcing Bulbs & Pre-Chilled Bulbs

Planning to force your bulbs or plant pre-chilled bulbs in winter? Read this! Forcing Bulbs & Pre-Chilled Bulbs

Insider Tips

  1. Plant dwarf iris bulbs at a rate of about 6 per square foot. These are petite plants and they looks best clustered together.
  2. Site your dwarf iris patch(es) where you'll be able to enjoy the incredible patterns and detail on the colorful petals.
  3. Over time, dwarf irises naturalize and spread gently into ever larger patches. Site with this in mind.
  4. For gardeners in zone 4, mulching with 2 inches of shredded leaves or leaf mold will help your irises overwinter more readily.
  5. If you live in a warm part of the country, where spring arrives early, make sure to plant your outdoor irises by late November to give the bulbs time to root in. Otherwise, they may begin to sprout before supporting roots have developed. 
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Success Snapshot

Light: Full to partial sun outdoors

Soil: Average soil

Depth: Plant 3-4” deep

Water: Average moisture

Uses: Garden beds, edgings, pocket gardens

Tip: Group bulbs for greatest impact

GUIDE: Iris (Dwarf) Planting Guide

They Start Out Looking Like This: