I fertilized my yard in March, including my irises, using Miloganite. I've since learned that a high nitrogen fertilizer means great leaves but no iris flowers.

I have about 15 iris plants, I really would like them to make flowers this year. Is there anything I can add to counter the nitrogen?

So mad at myself, I even have the note in my spreadsheet "not to use Milorganite on the irises, use a low nitrogen low first number." Wish I realized my mistake sooner.

Zone 6B, northeastern Massachusetts.

How high was the nitrogen content of the fertilizer you used? In my area, we use 10-10-10 or 15-15-15 fertilizer in the spring - not low nitrogen, just balanced.

I don't know of any way to counteract nitrogen once you've used it, unfortunately. It does get used up, though.

Thought Milorganite is fairly low in N

If you've already fertilized your irises with a high-nitrogen fertilizer like Milorganite, there are a few steps you can take to help counteract the excess nitrogen and promote flower production:

Watering: Ensure that your irises are receiving sufficient water. Adequate hydration can help flush out excess nitrogen from the soil over time. Water deeply, but avoid overwatering, as irises prefer well-draining soil.
Balanced Fertilizer: Apply a low-nitrogen, balanced fertilizer with a lower first number (nitrogen content) to provide the necessary nutrients for flower formation. Look for a fertilizer with a higher second and third number, which represents phosphorus and potassium, respectively. Phosphorus and potassium are essential for flower bud development. Follow the package instructions for application rates.
Organic Matter: Incorporate organic matter, such as compost or well-rotted manure, into the soil around your irises. Organic matter helps improve soil structure and fertility, providing a more balanced nutrient profile.
Mulching: Apply a layer of organic mulch around the base of your iris plants, such as straw or wood chips. This will help conserve soil moisture, regulate soil temperature, and reduce weed competition.
Avoid Additional Nitrogen: Refrain from applying any additional high-nitrogen fertilizers to your irises, as this can further exacerbate the issue. Stick to fertilizers with a lower nitrogen content and focus on providing a balanced diet of nutrients.
Monitor and Patience: Keep a close eye on your irises throughout the growing season. It may take some time for the excess nitrogen to dissipate and for the plants to redirect their energy towards flower production. Be patient and allow the irises to recover naturally.
Remember, irises are generally hardy plants, and with the right care and adjustments, they can still produce flowers despite the initial high nitrogen fertilizer application. By implementing these steps, you can help create a more favorable environment for flower development in your irises.

ilorganite is 6-4-0, which guarantees there's 6% nitrogen, 4% phosphorus, and less than one percent potassium in the bag. So the ratio between nitrogen an phosphorus is about the reverse of what it should be for irises.

I'd suggest doing a soil test around your irises.

Hi Freedom2B. Could you post some images of your iris clumps? They may already have flower buds formed and may still bloom yet this spring. Perhaps we can identify some developing stalks in your pictures.

6% nitrogen doesn't sound like that big of a deal to me.

Andrea, since it's low amounts, the application amount might be greater. But that's also why I recommended a soil test. It all depends on how much was applied.

With a 6-4-0 fertilizer, I don't think anything adverse will happen. The Nitrogen content isn't high enough to be much of a factor. As suggested by Daisy, a soil test would let you know what the soil has available for the plants, and what you may want to do to amend it. The plants most likely have already determined their bloom status for this year by this time, however.

alaska morbloom concentrate 0-10-10
available on line and at Home Depot