Planting & Caring For Bearded Iris
When planted right and in the right spot, Bearded Iris are very easy-to-grow.
Here's a breakdown of what you need to know...
Cultural Preferences
Soil Preferences
Bearded Iris grow best in a somewhat loose, moist but well drained soil of average fertility. Sandy or gravelly soils are excellent. In heavy clay soils that don't drain well it's best to plant in raised beds to ensure good drainage. You can also amend heavy soils with gypsum or composted organic matter to lighten the soil. As with so many other plants, constantly soggy or wet soil can cause root rot and other harmful plant diseases. So make sure to plant in well-drained soil!
Testing Soil Drainage
If you are uncertain about soil drainage in the area you intend to plant, it's well worth taking the time to test the drainage before planting.
To test soil drainage, dig a hole 12" wide by 12" deep in the planting area. Fill the hole with water and let it drain. Then, after it drains, fill it with water again, but this time clock how long it takes to drain. In well-drained soil the water level will go down at a rate of about 1 inch an hour. A faster rate, such as in loose, sandy soil, may signal potentially dry site conditions and possibly a need to add some organic matter to help with moisture retention. A slower rate indicates poor draining soil and is a caution you need to improve drainage, plant in a raised mound or bed, or look for plants that are more tolerant of wet or boggy conditions.
Soil pH Preference
Bearded Iris grows and flowers best in a moderately acid to slightly alkaline soil ranging between 6.0 to 7.5 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0.
Testing Soil pH
Soil pH is a measurement of the alkalinity or acidity of soil and is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline. If you're unsure about the pH of your soil, or whether or not it's suitable for growing Bearded Iris, it's a good idea to test the soil pH in the planting area.
You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil Sulfur, Aluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.
Learn More: What is Soil pH and How To Adjust It?
Light Preference
Bearded Iris grow best in full to mostly sun, however will tolerate a few hours of light shade or filtered sun during the day. We suggest at least 6 hours of direct sunlight per day for best growth and flowering.
How To Plant Bearded Iris
Scroll down for container planting instructions
Step 1
In well-drained soil, start by digging your planting hole at least two to three times as wide and no deeper than the root ball. The wider the hole the better. Place native soil removed from planting hole around the perimeter of the hole, in a wheel barrow, or on a tarp.
Step 2
Depending on the type, fertility and porosity of the soil in the planting area you might consider amending the native soil. When planting in dense clay or other compacted soil that doesn't drain well it is beneficial to plant in raised mounds or raised beds. If you use clay soil to form the raised bed thoroughly mix in some good organic matter, such as bagged top soil, sand or small gravel, and/or a good planting mix at a 50/50 ratio with the native soil. When planting in very sandy, quick-draining soil consider mixing in some bagged top soil or other organic matter such as compost to help retain moisture. When planting in a loose, moist but well-drained soil of average to low fertility there is no need for adding a soil amendment.
Step 3
To remove your Iris plant from the container it was growing in first squeeze the sides of the pot. Then very carefully remove the root ball from the container container without damaging the foliage. If desired, you can use a snipping tool to cut the container away.
Step 4
To plant, set the plant in the planting hole so that the top edge of the root ball is 1/2 inch or so above the ground level. You want the tops of the rhizomes (roots/bulbs) to be exposed slightly above the ground. If necessary, add some backfill soil mixture to the bottom of the hole to achieve proper planting height.
NOTE: If the soil in the planting area is poorly drained (constantly soggy or wet) improve drainage, plant in a raised bed with the root ball all the way above ground level, or select a different plant species more tolerant of wet soils.
Step 5
After setting your Bearded Iris in the planting hole, use one hand to hold the plant straight and your other hand to begin back-filling your soil mixture around the root ball, tamping as you go to remove air pockets. When you have filled the hole to the halfway point you can soak the soil. Then continue back-filling to the top edge of the root ball. To avoid suffocating your plant, avoid placing any soil or mulch on top of the root ball. Bearded iris prefer the soil around the top of their rhizomes/roots to be bare.
Step 6
Next, deeply water the planting area, including the root ball, to a depth equal to the height of the root ball.
Step 7
While with most plants we would advise mulching after planting, Bearded Iris do not like mulch around their roots. They prefer to have the tops of their rhizomes (roots) exposed.
How To Plant A Bearded Iris In A Container
When growing in pots, Bearded Iris appreciates a damp to moist but well-drained soil. Constantly soggy soil can and often will cause root rot or other harmful or deadly plant diseases. Therefore, we highly suggest using a container with a drainage hole(s) and a quality potting soil or potting mix or a 50/50 mix thereof. To ensure good drainage consider adding 20% perlite or pumice to the soil mixture.
As mentioned, make sure to choose a container with drainage holes at the bottom and also one that is large enough to allow for future growth. This might mean your planting pot would be at least 12 inches or more in diameter at the top of the pot.
Container color will matter as well. Not only will you want to pick a color of container that goes well with the flower and foliage color of your Iris, you'll also want to pick a container that matches the style of your home or other structures and other plants in the surrounding environment.
Many nursery & garden centers offer a wide variety of containers to choose from. Before heading out to buy a container take pictures of your home and the surrounding environment. Doing so will help you to choose just the right color and style.
Container Planting Instructions
Step 1
Before filling your container with the soil mix, we recommend lining the bottom with shade cloth or a porous landscape fabric. This will keep the drain holes from becoming stopped up with soil and roots. If you place gravel or other materials in the bottom of the container lay the fabric over it.
Step 2
To remove your Iris plant from the container it was growing in first squeeze the sides of the pot. Then very carefully remove the root ball from the container container without damaging the foliage. If desired, you can use a snipping tool to cut the container away.
Step 3
Pour a small amount of your soil mixture in the bottom of the container. Set the plant in your container and make necessary adjustments by adding or removing some soil so that the top edge of the root ball will sit 1" below the rim of the container.
Step 4
Backfill with your potting soil around root ball, tamping as you go, until the level of potting soil is even with the top edge of root ball. Leave the top of the rhizomes (roots) exposed with no mulch or soil on top.
Step 5
Water thoroughly until water starts to drain from the holes in the bottom of the container. Add more potting mix if settling occurs during watering. Thereafter wait to provide more water until the top 2 inches of soil has dried.
How To Care For Bearded Iris
Feeding - Watering - Pruning
Forst, avoid the use of fertilizers that are high in nitrogen, which is the first of the three numbers on a package of fertilizer. A little nitrogen is okay, but too much nitrogen causes excessive foliage growth at the expense of flower production. A fertilizer with numbers such as 6-10-10 is good. Bone meal and superphosphate are also good. Phosphate helps to build roots which help with flowering. A light application of fertilizer in the early spring and a second light application about a month after bloom will be beneficial.
Soil pH
Bearded Iris grow best in a moderately acid to slightly alkaline soil ranging from 6.0 to 7.5 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0.
How To Test Soil pH
Soil pH is a measurement of the alkalinity or acidity of soil and is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline. If you're unsure about the pH of your soil, or whether or not it's suitable for growing Bearded Iris, it's a good idea to test the soil pH in the planting area.
You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil Sulfur, Aluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.
Learn More: What is Soil pH and How To Adjust It?
How To Water Bearded Irises
Newly planted Bearded Iris plants will like some moisture to help their root systems to establish a root root system. But be careful not to over-water.
Tip: When watering with an automated irrigation system it's best to set your timer to water during the early morning hours and not in the late evening or at night, which can lead to the onset of fungus and other foliar diseases. During the first few weeks after planting, check soil moisture often and adjust irrigation time if necessary to keep the soil damp to moist, not wet!
At Planting Time
Immediately after planting deep soak the soil in the planting area, including the root ball, to a depth equal to the height of the root ball.
During the First Active Growth Season
In average garden soil you should not have to water your newly planted Bearded Iris every day. More often than not, this causes soggy soil conditions that can lead to root rot and other plant diseases. In the absence of sufficient rainfall, water only as needed to keep the root ball and surrounding soil damp to moist. Keep in mind that deep soaking less frequently is much better than splashing just a little water on the plants every day. Iris planted during the winter dormant season, when plants are not actively growing and evaporation is much slower, will require much less water. So, be extra careful not to overwater during winter!
Thereafter
Established Bearded Iris will rarely require supplemental water. Only during prolonged periods of summer drought or in arid climates will plants require supplemental irrigation. If you see leaves discoloring (becoming lighter in color) during a dry period this could be an indicator your plants could use a good deep soaking. That said, always check soil moisture before watering and only provide water if needed. Over-watering is the number one problem-causer when growing Bearded Iris.
How To Prune Bearded Iris
Spent blooms can be pinched or snipped off the bloom stalk if desired to keep the plants looking clean. After all buds have finished blooming, the bloom stalk off close to its base, just above the ground. Any browning leaves during the growing season should be removed as they appear. In the fall the leaves can be trimmed to about six inches above the ground.
Plant Long & Prosper!