The summer heat is tough on Louisiana irises. Here are a few tips to keep your irises happy and healthy.
- Remove old bloom stalks to keep your clumps attractive. Cut stalks off a couple of inches from the ground, removing all the lower leaves attached to the stalk. Also remove any yellow or brown leaves in the clump, as well as the stalks, disposing of them in your garbage, not the compost pile. Iris foliage can harbor the fungus disease Rust, and removing old iris material from your garden will help prevent Rust from spreading in the next season.
- Water and fertilize to maintain summer growth. Consistent moisture is the key to keeping the irises growing and NOT going dormant in the summer. A little fertilizer after bloom can help, but the irises are not growing rapidly and can’t use a lot (about half the usual amount). Allowing the irises to get too dry will trigger dormancy, and while they may not go totally dormant, they will stop growing and probably not start up again until the fall.
- What if the irises don’t look good? If the irises do start looking scruffy, you can cut off unsightly foliage. Any yellowed foliage should be removed. Don’t cut back foliage that’s growing well, but removing declining or yellowing leaves can stimulate new growth. Try to leave the center leaf in a fan alone since that is the latest to emerge and any new growth will appear there. If you have to cut out leaves, cut them to near the ground; don’t just cut them in half.
- Mulch. Several inches of mulch will help conserve moisture and keep down weeds. Ground pine bark and needles are excellent, but other finely ground organic materials (such as leaves) are also suitable.
- Seeds. If you saved any seed pods, now is the time to plant them. Score the pod with a sharp knife or box cutter with the blade extended just a quarter inch. Pry open the pod to remove the seeds. It’s best to plant them immediately in pots filled with garden soil, potting mix, or a combination. Cover the seeds with 3/4 inch of the medium, water well, and put them in a shady place. Keep the pots damp but not soggy. Germination will not occur until cool nights begin in late October or November. Make sure the seeds stay covered, so replenish the soil cover if necessary.
