Best Fertilizer for Irises – Reviews & Growing Guide

Irises require very little fertilizer. You may produce superb irises with plenty of huge flowers if you nourish them at planting time and before and after their bloom cycle. You can produce strong irises without using fertilizer if your soil is adequately rich.

But you, as a gardener, may be wondering what type of fertilizers you must use for your iris plant. Nowadays, it has been an on-demand question as to which fertilizers must be used for iris plants.

So, through this article, we will help you to choose the best fertilizers for your iris plant, and directions to use them.

How Do You Fertilize Iris?

How Do You Fertilize Iris?

When new growth begins in the spring, bearded irises in poor soil react nicely to modest fertilizer treatment. The fertilizer will promote flowering and good health without stimulating excessive leaf development. 

1 to 2 teaspoons of fertilizer per plant is a good starting point. Because direct applications might burn the rhizome, spread the fertilizer around the rhizome rather than putting it directly on top. Irises grown for the competition can be fertilized again with 1 tablespoon of fertilizer in late summer and mid-autumn.

Organic compost, rather than conventional fertilizer, can be used to feed irises. In the spring, cover the plants with a 2-inch layer of well-rotted and aged manure. During the growth season, the compost will decompose, giving enough nutrients for the iris plants. When using compost to fertilize irises, there is little chance of overfeeding. Make cautious not to sprinkle compost directly on the rhizomes, as this might cause them to rot.

We propose bone meal or super-phosphate, as well as a light balanced fertilizer like 6-10-10 or 10-10-10, depending on the quantity of nitrogen that is already present in your soil. We strongly advise you to test your soil.

A soil test may always be done at your local extension office. They will assist you in sending the samples to the lab for analysis and will return the results to you through the mail. If you like, you may also buy your kits online.

If you’re into gardening or hobby farming, though, building a relationship with your extension agent is a good idea because they can help you with future concerns.

When to Fertilize Irises?

When to Fertilize Irises?

Apply a little dose of fertilizer around the iris clumps in the spring, approximately a month before flowering. This is also true with dwarf iris, which blooms in March. In mid-to-late February, fertilize your dwarf iris with a low nitrogen fertilizer. Apply the same treatment to your intermediate and tall bearded iris in the month leading up to their bloom periods.

Sprinkle a spoonful of fertilizer around the freshly planted rhizome at the time of planting. Incorporate 12 kg of a low nitrogen fertilizer onto your garden bed if preparing a big area for iris planting. During the growth season, choose a location that receives at least six hours of sunlight every day. To keep the rhizomes from decaying, they need good drainage. To increase the drainage and fertility of a new bed, apply a 2-inch layer of compost to the soil and 2 pounds of 5-10-10 fertilizer per 100 square feet. To a depth of 10 inches, work the amendments into the soil.

You should fertilize your irises again after they bloom. This maintains them healthy and in top form for later in the year’s growing cycle. Wait a month or so after the flowers have faded, or in the fall, with enough time before winter, to ensure that the Iris receive the nourishment they require when they enter their winter dormancy.

Fertilize irises early in the spring, around 6 to 8 weeks before bloom, and then again after the blooms have gone. We propose bone meal or super-phosphate, as well as a light balanced fertilizer like 6-10-10 or 10-10-10, depending on the quantity of nitrogen that is already present in your soil.

Few Other Tips on Fertilizing

When the soil is humid but the leaves are dry, apply dry granular fertilizer. Chemical burns can be caused by fertilizer bits that attach to moist plants. High nitrogen fertilizers favor soft leaf development with few blooms, so avoid them. Make sure the fertilizer does not come into direct contact with the rhizome while side – dressing irises. Irises can decay if they are fertilized with uncomposted manure. Compost it for at least a year before putting it in your iris beds to lessen the risk of rot.

What to Look for in A Fertilizer for Irises?

What to Look for in A Fertilizer for Irises?

We need to keep four essential nutrients in the soil: nitrogen, phosphorus, potassium, and calcium. Most mixed fertilizers contain the first three nutrients, while calcium may be obtained separately as limestone.


Nitrogen is required for the production of new cells in all areas of a plant. Nitrogen is usually the most deficient of all the nutrients. Yellow-green stunted development is a sign of a nitrogen deficiency. Nitrogen is known to encourage rot problems, and so, the most important aspect is to avoid using anything with high nitrogen content.


Strong roots and stems, as well as intense flower color, require potassium (potash). Weak stems and yellowing or browning leaf tips and margins are signs of potassium shortage.


Phosphorus is required for the growth of roots and stems. This mineral also promotes the growth of fruit and seeds. The red or purple coloring of leaves is an indication of Phosphorus insufficiency.

If using a concentrated fertilizer, avoid allowing the fertilizer to come into close contact with the plant’s leaves and roots, as this may cause harm or death.

3 of The Best Fertilizers for Irises

6-10-10 Controlled Release Iris Food

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Schreiner’s Iris Gardens sells a nitrogen-free fertilizer made specifically for growing iris. It is recommended to apply one month before and after blooming. With their 6-10-10 Controlled-Release Iris Food, give these newly planted rhizomes a boost. When used as indicated, a 1 pound bag normally covers around 25 newly planted iris.

It’s best known for:

  • Improves iris bloom
  • Controlled-release fertilizer
  • The best nutrition for your iris plants
  • Improves the health of iris plants

Hope you check out this amazing product!

Container and Bedding Plant Fertilizer Spikes

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Fertilize irises in pots or garden beds quickly and easily with these pre-measured fertilizer spikes. This 50 spike pack gives Irises all of the nutrients they need at the root level.

The NPK ratio of these spikes is 3-5-6, which implies they may be utilized all year for irises’ development and sustenance.

These spikes also contain bone meal, feather meal, beneficial bacteria, and microbes in addition to macronutrients. This particular blend of goods causes a quicker nutrient breakdown in the soil.

Your irises will acquire drought, disease, and insect resistance with frequent spraying.

It’s worth noting that this organic product is designed to avoid nutrient loss and runoff. OMRI has it on its list of organic farming and producing facilities.

Don’t forget to have a look at this wonderful product!

Bone Meal All Natural Plant Food

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This is a cost-effective Irises fertilizer, especially if you have a large number of flowers in your yard or containers. A single 4-pound box will last for multiple applications.

This is a plant food made from the bone meal that provides organic phosphorus and nitrogen to blooming houseplants. It is made entirely with domestic bone meal and has no fillers.

The bone meal will help to strengthen the root system while also encouraging development.

It must be used at the time of planting for all sorts of fresh bulbs and perennials. Use spring or fall fertilization regimen for established plants. Mix the fertilizer straight into the soil and thoroughly water it to ensure that it is absorbed. This plant food has an NPK ratio of 4-12-0.

Make sure you check out this product!


Irises make the spring and summer gardens look extremely beautiful and pleasant with their ruffled and colorful blooms.

It is best to consider your final aim, or what the fertilizer’s purpose is, before selecting a fertilizer. This will assist you in selecting a fertilizer that will meet your existing needs.

It is best to choose a fertilizer that is heavy in potassium and phosphorus but low on nitrogen. Concentrate your efforts on bulb growth, as weak bulbs will result in fewer flowers as the plant is unable to reach its full potential.

So, make sure to buy the best fertilizers for your irises!


Is Miracle Grow Good for Iris?

Beardless iris are larger feeders and require more fertilizer, although all irises benefit from fertilizer once in a while! Miracle Grow is perfectly acceptable. But, as long as you don’t use it frequently during the season, it won’t harm your iris; you’ll simply get less bloom.

What Can I Feed Iris with?

Early in the spring, use an all-purpose fertilizer scraped in around the plants to fertilize. Avoid applying high-nitrogen fertilizers on the surface or haphazardly mulching with organic trash to prevent rhizome rot.

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