I’ll never forget the disappointment of walking out into the garden one spring, eager to see my irises in full bloom, only to be greeted by… nothing. A few sad leaves poking out of the ground, but not a single flower in sight. I had waited all winter, excited for that burst of colour irises bring, and instead, I was left feeling deflated.
It turns out, irises can be a bit fussy, and after some research (and a fair bit of trial and error), I figured out where I’d gone wrong. If your irises didn’t bloom this year, don’t despair. I’ve been there, and with a few adjustments, you can get them back to their beautiful best next year. Let me share with you the five most common reasons irises don’t bloom and, more importantly, how to fix it.
1. Your Irises Are Planted Too Deep
One of the most common mistakes I made when I first started growing irises was planting them too deep. I assumed, like most bulbs, they needed to be well-buried to stay safe and snug over the winter. Turns out, that’s not the case at all with irises. Their rhizomes (those thick, root-like structures) need to be close to the surface, with just a bit of soil covering them.
I learned the hard way that irises planted too deep will struggle to bloom because they can’t get enough sunlight. If you dig up your irises and find that their rhizomes are buried too far down, don’t worry—it’s an easy fix. Just replant them so the tops of the rhizomes are exposed or barely covered by soil. I did this with my irises, and the following year, they rewarded me with a much better show of blooms.
2. Too Much Shade: They Need More Sun Than You Think
When I first planted my irises, I didn’t think much about sun exposure. I assumed they’d be happy in a spot that got a few hours of sunlight in the morning and shade for the rest of the day. I was wrong. Irises *love* the sun. In fact, they need at least six hours of direct sunlight a day to bloom properly.
After I realised this, I relocated my irises to a sunnier spot in the garden. It was a bit of work, but well worth it. The next spring, my irises bloomed beautifully. If your irises are in too much shade, consider moving them to a sunnier location, or if that’s not possible, trim back any surrounding plants or branches that might be blocking the light.
3. Overcrowding: Give Them Space to Breathe
Irises are one of those plants that like their space. I made the mistake of planting mine too close together, and over time, they became overcrowded. When this happens, the rhizomes start competing for nutrients and water, which can result in fewer blooms—or, in my case, none at all.
If your iris patch has grown over the years and you’re seeing fewer flowers, it might be time to divide them. I usually do this in late summer or early autumn, lifting the clumps of irises, separating the rhizomes, and replanting them with more space between each one. You don’t have to do this every year, but every three to five years is a good rule of thumb. After dividing mine, I noticed a huge difference the following spring.
4. They’re Too Young or Too Old
Patience isn’t exactly my strong suit, and when I first planted irises, I expected them to bloom the very next season. I was a bit disappointed when they didn’t, but I later learned that irises sometimes take a year or two to settle in before they bloom. If your irises are newly planted and haven’t bloomed yet, don’t give up on them. Give them some time to get established, and they’ll likely bloom next year.
On the other hand, if your irises have been in the same spot for a decade and they’ve stopped blooming, they might be past their prime. In this case, it’s time to divide and replant. I had a patch of irises that had been in the same spot for years and had stopped blooming entirely. After dividing them, I saw a big improvement. So, whether they’re too young or too old, it’s all about timing with irises.
5. Nutrient Imbalance: Too Much Nitrogen, Not Enough Phosphorus
One year, in my eagerness to have the lushest garden on the street, I went a bit overboard with the fertiliser. I thought I was doing my plants a favour, but instead, I ended up with lots of green leaves and not a single flower. As it turns out, irises don’t need a lot of fertiliser, and too much nitrogen can actually encourage leaf growth at the expense of blooms.
What irises really need is phosphorus, which helps promote flowering. Now, I give them a light feed with a balanced fertiliser in early spring and again after they’ve finished blooming. If your irises are all leaves and no flowers, try cutting back on the nitrogen and focusing on a fertiliser higher in phosphorus. I found this little tweak made all the difference.
Don’t Give Up on Your Irises
I get it—watching your irises fail to bloom can be incredibly frustrating, especially after months of anticipation. But trust me, with a bit of care and attention, you can turn things around for next year. I’ve made plenty of mistakes in my gardening journey, but each one taught me something valuable, and now my irises are thriving.
Take a moment to assess what might be going wrong in your garden. Are they getting enough sun? Do they have enough space? Are you feeding them the right nutrients? Once you figure it out and make the necessary changes, you’ll be well on your way to a garden full of glorious irises come spring.
And let me tell you, when those first flowers finally bloom, it’ll feel like all the effort was completely worth it.