Expert: Long Island Gardener - 8/23/2006

Question
Zone 3, Calgary AB
I have daylillies planted in four seperate locations in my yard, most in full sun.  Although they were planted five years ago, I have lots of growth but still do not have any blooms, .  What do you think the problem may be?
I have used blossom fertilizer that I use on the rest of my flower garden.

Answer
Hello, OJ!

There are a few things that could halt flowering of otherwise perfectly healthy daylilies.  And let's face it, these plants rarely get sick.

You have already pointed out that your daylilies are getting "full sun" for the most part.  Number one reason for failure to bloom in most plants is now off your daylilies solutions list.

There's another possibility.  Do you mulch your daylilies?  With your cold temperatures zone down into the low Canadian digits, I am wondering if you have been cautious about hardiness for your daylilies and perhaps mulch them?  Or perhaps they are naturally mulched with falling leaves in the autumn.

If so, although these daylilies may have been planted at the proper depth originally, annual applications of mulch have added extra soil as the mulch decomposed.  A few years of mulching and your daylilies one day wake up and find they are too deep to set bud.  Solution here: Replant your daylilies; make sure to set them shallow.

Another possibility is that the Daylilies you have selected are not well suited for your particular climate.  

Thanks to the magic of mail order and other factors, people often try growing many nonhardy varieties different plants in very cold zones.  If so, your Daylily may never bloom.

I am not clear on whether your Daylilies USED to bloom and no longer do that.  If they were blooming when you bought them and planted them, they may not be tough enough to withstanding the winters in your region.  Local garden centers who sell blooming plants are basically making a promise they cannot keep, suggesting that a local customer who buys the blooming Daylily will themself have no trouble getting this Daylily to live happily ever after in their own garden.

You would be facing the same flowering troubles if you tried to grow hardy varieties of Daylilies that should be slipping into dormancy, but are now growing instead in the much milder Southern U.S. These plants fail to go dormant; their food reserves are depleted and the plants languish.  The result: No flowers next summer.

On the other hand, tender evergreen Daylilies are damaged by freezing temps; even if the plant survives the winter, it recovers too late in the summer to bloom, and you get lots of growth but no flowers.

Do you have any large trees or shrubs close by?  A strong, dominant root system will hog all available nutrients and moisture, leaving nothing behind for grass, bulbs or anything else you want to grow there.  Some trees can be remarkably efficient at staking their monopoly on all rainwater under the tree canopy.

Yet another possibility is that these daylilies are doing so well they have grown like crazy, are now crowded and need to be divided.

Smaller blooms, and fewer of them, is usually the first symptom - not an abrupt final end to flowering.  

But dividing is not something you should do in early summer.  Especially if the summer is going to be very hot, which was the case this year.  

Dividing too late in the season can result in frost damage to roots, which do not have time to get established before the ground in your area freezes solid.  

A Daylily damaged this way can take years to reach blooming size again.

Clumps of Daylilies should NEVER be divided closer to 6 weeks before your first frost.

If the plant's roots haven't had a chance to get established, the divided Daylily plant will suffer. The plants usually survive but at the end of the summer they can be quite small -- too small, sadly, to bloom the following year.

You mention that you have used blossom fertilizer on your daylilies.  Can you tell me please the numbers on that blossom fertilizer -- the N-P-K numbers, for instance 15-30-15 or 5-1-1?  Not all "blossom fertilizers" are created equal.

Finally, ever hear of Daylily Rust?  It is not a problem in the Canadian north, so far as I know, because this disease cannot survive long periods of freeze.  

Some Daylilies are resistant to Rust; others simply have serious symptoms.  Rust rarely destroys a Daylily completely.  The worst cases can weaken the plants to the point where they may not bloom.  Let me know if you see any Rust like symptoms on the leaves.

Other than all of the above, I cannot think of any other reasons that your Daylilies would fail to bloom this summer.  Unless we're talking perhaps about a high-Nitrogen low- or no-Phosphorous fertilizer, which would encourage lush green growth and zero buds.

Please let me know your thoughts on this.  I do believe however that one of these is the key.  If you have the name of your Daylily hybrids, we can check their hardiness rating(s).  Let me know!