Caring And Fertilizing Bearded Irises

Bearded iris’ characteristics

Belonging to the genus of Iris, the bearded iris is one of the types besides the breadless and crested iris.

It is called ‘bearded’ due to its three typical lower petals called ‘falls’ and the towering upright petals called ‘standards.’ The falls resemble the bearded as they surround the standards.

The stem grows up to more than 2 feet. The leaves are flattened and sword-like. It has thick rhizomes growing closer to the soil surface.

It tends to thrive in neutral to a little bit acidic soil. The soil should be well-drained and under full sun. The plant’s commonly planted in the spring or fall and usually blooms in the first year.

Once it grows, caring for and fertilizing bearded iris to get healthy and colorful flowers are quite easy. The colors vary like orange, yellow, purple, pink, white, bi-colors, and more, making it the most famous type in the iris genus.

The best fertilizer and time for fertilizing bearded irises

After planting in the ideal time between July to October, the flower is better fertilized 6 to 8 weeks before bloom or in early spring, after planting for the newly grown root, and after the bloom season is over.

Avoid fertilizers with a high nitrogen level because they can trigger rot problems. Instead, high phosphor fertilizer is more suggested, like 6-10-10 or 10-10-10.

As the iris belongs to the rhizome, its root development will be well supported by phosphorus. During fall, fertilizer with zero nitrogen (0-10-10) is also recommended.

Some research also found that fertilizer for roses also works well for irises. Besides chemical fertilizer, organic compost can also be a great nutrient source.

Steps on fertilizing bearded irises

  1. Check the soil condition. Fertilizers are mostly used in nutrient-less soil or bed. Irises in healthy soil could survive in little to non-fertilizing at all. Over-fertilized soil could lead to other problems.
  2. Determine the lacking nutrients and find the right fertilizer for the soil.
  3. Prepare the fertilizer. Each plant could have 1 or 2 tablespoons of chemical fertilizer. In comparison, 2-inch-thick compost could be given to each plant.
  4. Spread the fertilizer or compost around the root, not directly on top or touching the root. Fertilizing bearded iris should be done carefully, or the fertilizer and compost will burn the root.
  5. While preparing the soil for planting, mixing the compost and the soil could be the mulch. Yet, place the mulch mixture 4”-6” from the root.  

Tips on growing, caring, and fertilizing bearded irises

  • Do not mulch or put fertilizer directly touching the rhizome.
  • Remove old foliage and winter mulch as soon as spring appears.
  • Fertilizing right after the first bloom season encourages re-blooming.
  • Do not water too often or too much. Wet soil causes rotting roots.
  • Let the root breathe. Do not cover whole fully the rhizomes under the ground.
  • Provide staking once they grow tall. They tend to fall over without support.
  • When the blooming season is finished, remove the flower stem, not the leaves, to its base. Cut the dry and yellow leaves only.
  • Covering the root with 1 or 2 inches of sand topped with a thin bough layer could be winter protection.
  • Inspect the plant routinely to remove pests and diseases like borers, nematodes, slugs, thrips, whiteflies, blight, aphids, and more.
  • If a part is infected, directly remove the part before it infects others.

Signs when fertilizing bearded irises are needed

To boost growth, fertilizing irises is also needed to cure certain conditions. The signs and conditions include:

Stunt or no flowers: there are many causes of this condition. It could be lots of irises growing closer to each other or lacking sunlight. Or else the plant has nitrogen deficiency.

Discoloration: fertilizing bearded iris with phosphorus could cure this condition. The preferred fertilizer is the bone meal or equal to 10-10-10.

Yellow leaves: there are two possible causes of this condition: potassium or nitrogen shortage. Just like the solution for discoloration, adding 10-10-10 fertilizer will help. Besides, fungi also make leaves turn yellow.

Bearded irises after blooming

As soon as the flowers dry, remove the spent flowers and their dried stems. Any dead foliage also needs to be cut off. Removing the dry parts could prevent diseases and pests and improve the look of the plants.

Post-blooming is also the best time to divide the irises because they could start a new growth without competing with other closer irises.

This plant tends to be a crowded clump after 3-4 years. Then, fertilizing the bearded iris should be done, as it could stimulate the new growth of the dead parts and help the plants re-bloom.

If gardeners wish for a re-bloom, prepare the right conditions, including the soil, sun, and drainage. Some claim that re-blooming bearded iris is a heavy feeder meaning more nutrients and water are needed for the next bloom.  

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