How to Care for Peruvian Iris

Plant Peruvian iris rhizomes in the late summer or fall in soil that is rich in organic compost or peat moss. Choose a sunny area where the drainage is good.

Dig planting holes 8 inches apart, and make them slightly larger than each rhizome you plan to plant. Plant each rhizome so it will be barely covered after you fill the planting hole with the soil mixture you removed.

Water the area deeply after you plant. If winter rains do not keep the soil moist, supplement natural rainfall with irrigation. In dry spring and summer weather, also water deeply once each week or every 10 days.

Fertilize with a plant food having an N-P-K (nitrogen-phosphorous-potassium) ratio of 5-10-10 once or twice each growing season. Do not feed your Peruvian iris after the middle of August.

Cut the top foliage to within 6 inches of the soil level after frost causes the irises to die back. Also clean up any plant debris on the soil surface. If your soil freezes, spread a layer of mulch 4 to 6 inches deep over the growing area. Organic compost, leaf litter and straw are all good materials to use as mulch.

Dig up and divide older plants in the summer three or four years after you plant them. With a spading fork, carefully lift large clumps from the soil. Wash the root and rhizomes, and then cut them into pieces that resemble fans, using a sharp knife. Store them in a cool area until the fall, when you can plant them as you did the original rhizomes,