Irises can be mulched if the mulch is kept away from the rhizome. This will prevent the bulb from rotting and allow excess water to drain down into the soil. Mulch can increase the chance of water sitting against the stem which will cause the iris rhizome to go mushy and die. Bark mulch can be kept on the soil 1-2 inches away from the base of the iris.
How to mulch around irises safely
There are 5 easy steps to safely mulching around your irises without causing problems such as rhizome rot. Start by removing weeds, choosing a good quality mulch and spreading it evenly across the soil. Check out more on the 5 easy steps to mulching around irises below.
1. Remove weeds
Before adding mulch around your irises make sure you remove all the weeds that you can see. Do this by hand to avoid damaging your iris bulbs. Weeds will compete with irises and can stunt or reduce their growth as the weeds take water and nutrients away from the bulbs.
2. Choose your mulch
Choose a good quality mulch for your irises which could include bark chips, tree mulch or straw. All of these mulch types have benefits for your irises and the soil. The mulch will prevent weeds, feed soil bacteria and worms which will release nutrients into your soil.
Bark mulch will break down more slowly than light mulches like straw, hay or sugar cane which will break down in 3 months and need to be topped up.
3. Spread the mulch 2 inches thick
Spread the mulch out evenly around the iris bulbs to a maximum depth of 2 inches. This will ensure that rain can still flow through to the soil and it will avoid excess mulch from flowing over the iris bulbs. Use a rake or spread the mulch with gloved hands to this thickness on the soil around the bulbs.
4. Move mulch away from iris bulbs
The most important step when mulching irises is to make sure that mulch is moved away from directly touching the bulb. This will avoid the moisture from sitting against the rhizome and causing rot. Use your hands or gently move the mulch back 1-2 inches from the rhizome with a hand spade.
5. Water the mulch thoroughly
Once you have laid the mulch, use a garden sprayer hose to water the mulch thoroughly and hold it in place. This will prevent the mulch from blowing away on windy days, it will help it knit together and water your irises at the same time.
Best mulch for irises
The best mulch for irises is a mixed tree mulch with both larger bark pieces mixed with leaves and stems. This is commonly made from tree trimmings from street trees and includes a mix of brown and green materials. This mulch type adds tremendous value to your soil and will help to feed worms and soil bacteria.
Other mulch options for irises include straw, hay or sugar cane mulch. These light mulches will help to feed soil bacteria and worms while keeping weeds away. Top these lighter mulches up every 3 months to keep the depth to 2 inches.
Does mulch hurt irises?
Mulch can hurt irises if it is placed over the rhizome as it will trap water and can cause rot. The mulch can hold rain water or water from your hose against the rhizome which can go soft, black and eventually kill the plant. Keep mulch 1-2 inches away from the rhizome to avoid the problem of rot.
Can you mulch irises with pine needles?
Pine needle mulch can be used around irises but it is best if it is kept a further distance away from the base. Pine needles can travel and cover iris bulbs so keep them further away. Mix pine needle mulch with bark mulch to help to hold it in place. Pine needles break down slowly and can be topped with hay or bark mulch for added depth.
How do I keep weeds out of my iris bed?
Keep weeds out of your iris bed by clearing the bed of visible weeds by hand first. Bark or sugar cane mulch can then be added to the soil to a depth of 2 inches. Keep the mulch away from the base of the iris plant to avoid rot.
Keeping the mulch layer to 2 inches will help to block the light that can reach weed seeds and prevent them from growing.
Do Irises need mulch?
Irises do not need mulch but the soil and garden beds will benefit if the mulch used. Use a layer of 2 inches of bark mulch to prevent weeds. This will help to feed your soil at the same time so there is always a great reason to mulch including the long term benefit of feeding your soil including the soil bacteria and worms.
How to keep grass and weeds out of iris beds
Keep grass out of iris beds by using a solid edging including pavers, stone edging or stainless steel edge. This will help to block weeds with runners from reaching through to the iris beds. Buffalo or Couch grass can easily spread into your iris beds if there is no physical barrier.
Keeping the beds mulched with a layer of bark mulch will help to prevent additional weeds from growing in your garden beds. Keep the mulch layer topped up to 2 inches and away from the base of your iris plants.
Can you mulch around Irises? | Summary
Mulch around irises to keep weeds away and help to reduce their watering needs. The most important aspect when mulching irises is to keep the mulch 1-2 inches away from the bulb to prevent rot. Mulch is a fantastic ingredient for any garden and work perfectly when placed on exposed soil.
Do not mix mulch through the soil otherwise you can risk starving your iris plants of nitrogen and increasing the water drainage from the bulbs. Always place mulch on the surface of your garden beds for the best results.
I am an accredited practicing dietitian, experienced gardener and a dedicated cook. I love writing and sharing my experience so you can learn from my successes and mistakes.