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Louisiana Iris Growing Guide

Header Louisiana Iris - Garden Express Australia

What is Louisiana Iris?

Louisiana Iris (Iris louisiana) also known as American Swamp Iris or Water Iris is a clump forming evergreen perennial. It is part of the Iridaceae family and is native to Southern USA. Grown from a rhizome, Louisiana Iris has thin, sword-like foliage with open faced blooms held aloft on thin stalks during late Spring to early Summer. They come in a wide range of colours such as whites, pinks, reds, blues, purples and yellows. They have adapted to a wide climate range, making them very suitable for Australian ponds and gardens. They grow in full sun to dappled shade. Adequate water and the use of mulch to protect the rhizomes from the hot sun is needed for the Louisiana Iris to flower well and have an excellent growth rate. Louisiana Iris can be planted in the ground, in pots but grow best when waterlogged such as in or around ponds. They grow well close to water, in fact the wetter their roots the better they seem to grow. If planted into ground (that is not near a water source) then they will need regular water and kept moist during growing time. If planting in a pond, plant your Louisiana Iris in a pot and put it in shallow water or submerge them up to 10cm of water or so that the water is over the top of the pot. They are moderately frost tolerant. They come in a variety of sizes; dwarf, medium and tall.

Benefits of Growing Louisiana Iris

Louisiana Irises can be grown in your flower garden or submerged in water in pots as pond water plants.

How to Grow Louisiana Iris

Climatic Zones

Cold to tropical.

Plant Size

Sizes vary.

When To Plant Louisiana Iris

Plant in Autumn.

Soil Preparation

They require acidic soil. Dig through well broken down compost and animal manure. Do not add lime as Louisiana iris will not tolerate lime as this raises the pH level.

How To Plant Louisiana Iris

Plant in full sun to dapple shade, 50cm apart with the rhizome just below the soil surface. Mulch and water in well if planting in a garden bed or pot.

Louisiana Iris Plant Care

During dry periods, if planted in the ground or in pots, they need a regular soaking to prevent the rhizome from going dormant.

Louisiana’s Iris are heavy feeders and are acid loving plants. They are best fed a light dressing of a complete Acid Fertiliser such  as Azalea and Camellia fertilisers. This can be done before flowering.

Keep them mulch regularly. Mulched in Autumn to protect from the cold and in Summer to keep the moisture in and to prevent the sun burning the rhizomes.

Every 3 or 4 years the rhizomes will need to be thinned out. When doing this it is best to remove all Irises and renew the soil by adding in broken down organic matter as the original old soil will be stale and worn out