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How to Feed Iris Plants

Maria Taglienti-Molinari/Brand X Pictures/Getty Images

Iris plants are as tough and durable as they are beautiful, so it’s little wonder that they enjoy popularity among home gardeners. They’re undemanding, easy keepers and even thrive well without fertilizer. This is a fine thing, since it’s been traditionally believed that feeding irises was downright dangerous to their health. Modern growers and hybridizers have discovered that the reverse is true: proper feeding actually does enhance the vitality and blooming capacity of iris plants. To maximize performance of these beauties, give them a little boost with proper feeding for dazzling results.

Feed spring blooming iris varieties only once each year -- right after they’ve finished flowering. Spread 1/2 cup of a good 5-10-10 or 5-10-5 fertilizer around each clump. Don’t put any of the product directly onto the plant. Estimate where the rhizomes are situated underground and apply the fertilizer in a band just beyond that point. Follow the packaging instructions carefully.

Use a gardening fork to cultivate the treated soil and work the fertilizer into the top 1 or 2 inches of it.

Feed re-blooming iris varieties twice each season. Fertilize in the spring just as soon as new growth appears. Apply 1/2 cup of a good 5-10-10 or 5-10-5 fertilizer to each clump, just beyond the rhizomes. Don’t get the material on the plant.

Cultivate the fertilizer into the top 1 or 2 inches of soil.

Repeat the application for re-bloomers immediately after flowering ends for the season. Cultivate the area well.


If your irises aren’t blooming up to par, you may be over-feeding them.

Don’t feed manure to your irises. It’s high in nitrogen, which promotes rot in these plants.

Stop fertilizing your iris plants by mid-August. This will give them plenty of time to toughen up, harden off and prepare themselves for winter.

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