How to Keep Weeds Out of Iris Beds

Iris beds are beautiful additions to any landscape, but keeping them weed-free can be a chore. Weeds compete with iris plants for water, nutrients, and sunlight. They can quickly take over your iris planting if left unchecked. However, with some knowledge of iris care and a good weed control strategy, you can keep your iris beds looking their best.

Why Weed Control is Important for Irises

Irises are perennial plants that come back year after year. But letting weeds take over iris beds will make the plants weaker over time. Strong weeds literally crush iris roots, keeping them from getting to important resources. Having weeds grow around iris rhizomes makes it hard to pull them out and divide them when needed. Also, weeds are home to bugs and diseases that can hurt your irises. Iris plants have the best chance of being healthy and strong if you keep the beds free of weeds during the growing season.

How Weeds Spread in Iris Beds

Weeds invade iris plantings mainly by seed. Some common iris bed weeds like crabgrass and chickweed spread solely by seed. Others like nutsedge and quackgrass can also spread by rhizomes or tubers. Seeds blow into beds on the wind, spread by birds, or hitchhike on tools, shoes, and mulch. Neglected beds near iris plantings quickly become reservoirs of weeds that spread to the irises. Once weeds gain a foothold, diligent effort is required to bring the infestation under control.

Cultural Methods of Weed Control in Irises

Keeping weeds at bay requires utilizing a range of control methods. The first line of defense is cultural practices that discourage weeds and favor the irises. These include:

• Amend soil deeply prior to planting irises. Weed seeds lurking in the top few inches of soil will be buried too deep to thrive.

• Mulch beds with 2 inches of pine straw shredded leaves or other organic mulch immediately after planting and replenish as needed. This blocks light from reaching emerging weed seedlings.

• Set clear bed edges to keep grass or weeds from growing into the beds around them. You can use plastic, metal, stone, or brick for the edges.

• Space iris rhizomes properly 12-18 inches apart depending on variety. This allows the foliage to fill in quickly and shade out germinating weed seedlings.

• Water thoroughly to encourage deep iris root growth. Plants with extensive root systems are better able to outcompete weeds.

• Fertilize according to soil tests to maintain iris vigor without over fertilizing weeds

• Remove weeds promptly while they are small and easy to eliminate.

Using Herbicides in Iris Beds

While cultural practices form the foundation of weed control, herbicides are often needed to fully protect iris plantings. Several types of herbicides can be used safely around irises:

• Preemergent herbicides create a weed-suppressing chemical barrier at the soil surface. Products containing pendimethalin, prodiamine, dimethenamid, and isoxaben are labeled for use in irises. Apply before weeds germinate in early spring.

• Postemergent herbicides kill weeds that have already begun growing. Grassy weeds can be killed with fluazifop, fenoxaprop, clethodim, or sethoxydim without hurting irises. Glyphosate-based products will kill any weed that is actively growing, but they must be kept away from plants you want to keep alive.

• Combination products that provide both pre and postemergent control are available. These include Gallery (isoxaben) mixed with either Treflan (trifluralin) or Snapshot (trifluralin + isoxaben).

Always check product labels thoroughly and follow directions carefully when using herbicides in iris beds.

Hand-Pulling and Digging Established Weeds

Even in beds treated preventively with herbicides, some weeds will slip through. Mature perennial weeds can be challenging to eliminate from among iris plants. Hand-pulling and digging are effective options for dealing with isolated perennial weeds or small patches.

• Use a dandelion fork or weed popper tool to loosen soil deeply under each weed clump.

• Grasp the leaves at the base and pull firmly to lift the entire root system if possible.

• For stubborn weeds, use a shovel or trowel to dig out as much of the roots as feasible. Remove every piece to prevent regrowth.

When pulling weeds around irises, be careful not to damage the shallow rhizomes by accident. Mark iris locations first and proceed carefully.

Proper Weed Disposal

Eliminating weeds from iris beds is only half the battle. Proper disposal is essential to prevent further spread:

• Remove weed debris promptly from the planting bed after hand-pulling.

• Place pulled weeds into plastic bags to transport for disposal. Do not add weeds to compost piles.

• Destroy weed seeds and roots by burning if allowed, or dry thoroughly and discard with household trash.

• Clean tools and shoes thoroughly after working in weedy areas before returning to iris beds.

Preventing seed production and distribution prevents future weed problems in the iris planting.

Ongoing Weed Prevention

Weed control in iris beds is not a one-time task but rather an ongoing process. Consistently implementing the following practices will minimize weed issues over the long-term:

• Inspect beds frequently and remove weeds when small.

• Reapply mulch layers as needed to block light from weed seeds.

• Use preemergent herbicides on a schedule to maintain chemical weed barrier.

• Adjust irrigation and fertilization practices if weeds become excessive.

• Promptly eliminate any perennial weed patches that develop using targeted digging or herbicide application.

• Edge beds at least twice per year to prevent grass encroachment.

With proper iris culture and vigilant weed prevention measures, you can enjoy lush, flowering iris displays season after season. Don’t let weeds steal the show!