an awesome overview with pics of the warmer-zone dormancy, and so wonderful to see how a potted garden can be as lovely, or more so, than in-ground! Bravo!

Lovely, lovely gardens, Lyle. Well done!

I just went back and read this thread about summer dormancy, I have had several plants experience it just recently and are now growing new foliage and recovering. 'My Path" did very well for me this year and looked great then within a couple of weeks just went almost out of existence but is now recovering nicely, had several more that just in the past few days have started showing some new growth. I thought I had lost them completely.

Summer dormancy a lot here. I just wait the floppers out and they go off and running again sooner or later. I do not consider it a problem.

This is the first year I have paid any attention to summer dormancy, I guess I previously just thought the plant had died. I like for the foliage to look green and healthy all the time, not turning brown and dying in hot weather. I wish there was a list of cultivars that had this trait. I think it is something to be considered when hybridizing also. I have read that daylilies that have a year or two of very successful blooming will sometimes experience a year of summer dormancy, so I guess in that case they have earned their rest period. Those slackers that have not performed extremely well however should not be taking a break in my opinion, I have some that just bloomed once then no re-bloom and then went into summer dormancy. I am waiting to see if they re-bloom now.

Reviving this thread because I am already seeing summer dormancy earlier I think than I ever have, and it has not been that hot this year. We did have a three week period of drought, so maybe that is still affecting the plants. Lately we have had more than an abundant amount of rain. I have had some rot in the daylilies also. But what I am seeing I am now attributing to summer dormancy and I do not like it.
Lots of leaves dying off, plants shrinking down, some of them to almost nothing. I have had this happen, more in July, August, Sept., this just seems very early to be experiencing summer dormancy, and it seems many more plants are exhibiting
it.
Is it possible that the record low few days of cold in the winter, then the very late freeze in March has caused the plants to be in a weakened state and fall victim?
I am still seeing freeze damaged buds and odd reduced sized blooms.
Here are some photos of plants I am thinking are exhibiting summer dormancy.





I suppose it is appropriate that 'Winter Memories' is showing the greatest impact from summer dormancy.
Is there anything that can be done to prevent summer dormancy, any way to predict which plants might show it?

I have been worried about so many of my plants showing to be "hard dormants"(hard hit by summer dormancy). When I first got into daylilies I thought dormancy was just a northern garden thing. I had never heard anyone even mention that we have summer dormancy. I think of it as a southern problem, but I see a lot of people posting about it are pretty far up north. Many seem to associate it with dry hot weather, but this seems to be the hardest my garden has been hit with summer dormancy and this is one of the wettest months of July we have had in a long time.
I just stated that this July seems that summer dormancy is the worst it has been, but that is just based on my poor memory. I was so concerned about the problem I went down to the garden just to really take a long hard look at how severe the problem was. I realized just how closely it resembled rot starting, nothing sets me in a panic mode more that the thought of rot. It also very closely resembles plants being sprayed with a weed killer, had I again mixed the wrong chemicals, had I let the wind blow the spray onto the daylilies?
But when I came back into the house I was feeling a bit more reassured
because the summer dormancy did not seem to be as bad as I had built it up in my mind. So, that got me started thinking about "Is this really the worst summer dormancy has ever been in my garden?" I started searching for posts I had made over the past few years and it seems each year summer dormancy seems worst that the last. That in itself made me feel somewhat relieved.
It made me realize that my memory is not a very reliable source of information. I resolved to try and give myself something to base the severity of summer dormancy on next year.. take photos of the worst affected plants this year.
I posted a few in the post just above this (seems I am the only one having this problem). But, here are some more of the worst summer dormancy affected plants in my garden for future reference. I did realize while doing this that just because a plant has summer dormancy one year does not mean it will every year, surprisingly the plants that make the rot list or the summer dormancy list are not always the same year after year, but some unfortunately are. It will be interesting for me to review these photos in the fall and then the spring and see what type of recovery the plants have made.
'Happy Mothers Day':

'Dueling Colors':

'Lickety Split':

'Judy Farquhar':

'Bone Shadows

'Sunset Key':

'Solomon's Riches':

'My Friend Phil':

'Fire Marshall Bill':

'Spacecoast Pattern Plus':

'Dixie Sweetheart':

'Muddy Creek Malarky':

'Queen Elizabeth':

'Kabuki Drama':

'Black Plush':

'Divine Comedy':

'Parisian Adventure':

'When Stars Align':

'Violet Etching':

'Grace and Mercy':

'Great White':

'Lydia's Regal Robe':

'Masked Phantom':

'Freaky Good':

'Previledge In Purple':

'Celtic Veins':

'Tennyson':

'Inner Destiny':

'Applique Prism':

'Bragging Rights':

'All In Favor':

I did not go to great efforts to select the worst affected plants, nearly all registered plants in my garden are suffering to some degree from summer dormancy, but these were the ones easy to spot as I walked the garden.

I am like you Larry, this is the first year that I have noticed this problem being this bad. A few of mine have died back completely, but some of them are beginning to show a little green. Also, when do you usually begin to plant your seed?

alma47,
Up until last year I would always plant most of my seeds in August, but that is just so hot and miserable. So, I did some experimenting with planting seeds in Oct., Nov. Dec., and even January last year. I had success in all those months. But, the best success I had was planting seeds in early October, that provided me with my best seedling crop ever, not a large percentage of them have bloomed this first year, but it did seem to me that just as many bloomed the first year as did the ones I used to plant in August. The January crop of seeds was hard to judge the success rate because the squirrels kept digging all those up time after time for some reason, when the December planted seeds were just a few feet away and they pretty much left those alone. It has made me ponder whether critters might have certain months when they are less active and certain months when they are most active.

Squirrels definitely have.
Here, they are happy eating tree buds so leave everything alone in the garden at that time. Once the buds pop, down they come looking for other food sources. So, early tulips never get touched as that coincides with tree buds. Later tulips are a different story.

Your critters also may have a preferred food source at that time your seedlings are untouched.

Larry, thank you. Hope you don't have so much trouble with the squirrels this year. I will be planting in cups, but I don't have nearly as many seeds as you do.

I searched and searched for any scientific information, or even old wives tales for information about summer dormancy, heat dormancy, and even drought dormancy in daylilies.
There is very little information I can find on the subject. But, I have often been told that daylilies are monocots similar to corn, so I thought to look for information about heat stress on corn (many more dollars put into research on commercial food crops than will ever be spent on research for daylilies).
This was one of the best articles I found (easy to understand) and I thought highly informative and gave what I thought was a pretty good explanation of the causes of heat dormancy in corn and soybeans, and hopefully most of this information can also be applied to daylilies.
https://cropwatch.unl.edu/2016...
The most important part to me is listed under:
IS THERE ANYTHING THAT CAN BE DONE TO MITIGATE EXTREME HEAT STRESS ON PLANTS? Then lists nine things that could be done for corn and soybeans, they may not all apply to daylilies but the general principals I feel would.
Basically, it just says that small amounts of shallow watering can be a benefit, and will not necessarily cause the roots to be shallow or not continue to grow deeper due to other reasons. I think we have all read that it is better to water daylilies deeply so the roots will grow deeper. It also states that soil fertility can impact the degree to which heat stress can affect plants (plant stomatal conductance and the transpiration rate were observed to be lower). The article mentions the advantage of having additional residue on the soil surface as a result of reduced and no-till growing methods, which I understand as being mulch in the case of daylilies. The mulch helps reduce the soil temperature and thus is beneficial for root growth and water and nutrient uptake. Also the study suggest that adding micronutrients because they also modified stomatal function and activated physiological and metabolic processes that helped with tissue water potential and heat stress tolerance.

I have several plants that go dormant mainly as they are done blooming. Those plants have no rebloom genetics or evergreen tendencies. Those plants are also hard dormant and are very winter hardy- although most of my other plants that remain lush are also very hardy as well. There are only a few that will begin going dormant even before first blooms appear. They will then get a few small leaves as the season nears an end before frost. They don't seem to be affected by heat or lack of rainfall, because they do it regardless of weather conditions. I have also noticed that many of them have narrow strappy foliage, rather than the wide foliage influenced by evergreen or reblooming genetics. In my garden, those with wider leaves can get sunburned easily in the early stages of rapid spring growth if it becomes really hot. Those plants don't seem to go dormant though and continue producing new leaves throughout the growing season until they are frozen back. Those going summer dormant will only produce one or two small new leaves no matter what kind of care they are given, and no more. I tend to notice it most when I am moving clumps. Those with lush foliage can be carried easily by the plant, but the dormant leaves will let go from the weight when you pick them up.

I can say that I do have a few newly acquired plants that look a bit like your photos, and those plants have remained small. We haven't had the heat related stress that many places are experiencing, and while it is dry, it isn't overly dry or droughty yet. I haven't ever had rot, so I can't comment about that aspect or if plants share any similarities. While it might be unsightly, part of me really doesn't mind that some go dormant. If I were overly ambitious, I would try harder to put those plants in their own section of the garden, but.....

Weeds seem to be doing exceptionally well though!!! Crabgrass is killing me!

I went over to the Nursery the other day, the one I get my fine pine bark from. I happened to mention heat stress to the person at the nursery he told me that he thought one reason heat stress was so bad this year was because we had three weeks of drought, then a few weeks of rain almost every day, now we are back in the drought stage and he thinks the plants try to adapt to the dry weather, then they get used to rain every day, then try to readjust to the drought conditions and it just puts too much stress on them.
That may be true, I was watering this morning when I happened to see this scape on 'Pink Super Dormant, it has actually blasted twice and still had buds and blooms on it. The scape was abnormally large at the base then blasted it looks like, then kept growing but not nearly as thick and blasted again. This just illustrates how our weather has been this year.

Browning foliage is one of the reasons I would like to cut back on the number of daylilies I have and add other perennials that do not have this tendency. The garden just looks so tired and bedraggled now. I've cut the foliage back on 20 or 30 daylilies to clean up the garden some, but carpal tunnel syndrome limits the amount I can do each time. A few of the daylilies I cut back a couple weeks ago are already getting pretty, green leaves again.

blue23rose,
I watched a video form Oaks daylilies yesterday and he said they used a weedeater on their plants when they started looking so ratty, and there too their foliage came out in a couple of weeks looking pretty and green. Someone else on here stated they loved the way their foliage made such pretty clumps after being trimmed back and put out nice new fresh green foliage. I also have heard of people just mowing the foliage down, but my mower does not go high enough with the height adjustment for me to feel comfortable doing that. Plus my plants are not positioned so I would not be crushing some while trying to mow others. Right now I have a lot of rebloom scapes still that should bloom, so I don't really like the idea of non selective trimming of the entire plants.
I spend a lot of money on chemicals to control rust, leafstreak, leafminer, etc. to keep the foliage looking nice and green, but none of the chemicals I buy help one bit with summer dormancy caused by heat stress. I have moved summer dormancy right up their with rust on my list of daylily faults .

Larry if you're looking for scientific articles about heat stress in monocots try turf/grasses, such as the technique of "syringing" which sounds rather like what you found for corn. I think I read a while back that fans may work better than syringing (sometimes used on golf greens) but I can't see anyone setting up a large scale fan system for daylilies! Something like a quarter of all flowering plants are monocots but turf has been particularly studied because of its use in various sports. I guess because of the volume of corn grown it would have been much studied too and maybe in this context annual vs perennial doesn't make as much difference.

One thing that would be interesting to look at scientifically is whether the same plants that go summer dormant (meaning dying back as well as not growing) actually do go dormant in other summers. By that I mean in the technical, not daylily, use of dormant which doesn't require that the foliage dies back, it just means that the plant is not growing at that time. Could it be that they always go dormant (stop growing) in summer but only extreme circumstances cause the leaves to actually die?

@sooby
I can't even say that many of my heat stressed daylilies go dormant because they still put out scapes and wimpy little blooms and often while the outer leaves are dying new green is starting to grow like new fans in a clump. I just keep seeing it referred to as summer dormancy so I often use that term myself. I can say that the same plant my not be affected or as badly affected by heat stress every year, while others that don't show it as much some years show it a lot more in other years. In other words my list of the most affected plants by heat stress would not be the same every year. Maybe some had more winter damage that weakens them as late as summer? I really have no idea why.

@Seedfork Even here in the mountains my daylilies are struggling badly. It doesn't seem to matter whether I moved and/or planted them last Fall or this Spring. Many have lots of dead foliage, though they also bloomed. I am going to cut them back because I found that one new plant, still in its grow bag, died all the way back and is now a nice small green clump. I think some of the newest plants, whether planted Fall or Spring, are not going to make it, though I will leave them in the ground, just in case. I have never had a year where I have had so much difficulty growing daylilies and attribute it to the severe cold in December, coupled with a rainy Spring, followed by a very dry Summer. If all of that doesn't stress a plant, I can't imagine what would. It has certainly stressed me!!

I love this subject! I should say that I don't have a scientific bone in my body, but I am a long time gardener and I hope I have my terms correct.... maybe. This topic coincides with another that cost me a friendship, so I need to tread carefully here.

From what I understand in dummy language, summer dormancy differs from stress related inactivity. Some of my more evergreen plants slow to a crawl when it is extremely hot and dry, but they continue growing new leaves, even slowly. My "summer dormant" plants begin to go down as they are done blooming and will only grow a couple small leaves that will turn yellow at the first sign of frost. Anyone growing Neon Flamingo or Heavenly Angel Ice will observe similar behavior. (I hope) I suppose that might differ if you don't have winters.

This first photo is showing what I call "summer dormancy". This plant has several clumps that all do the same thing year after year regardless of the weather. It will grow a few leaves later on, but they will never get very big. This type of daylily is especially nice in mixed plantings with annuals that take up the slack when the daylilies are done. These plants, at least for me, are very winter hardy and generally have strappy leaves. They normally don't rebloom either. I call them "hard dormants" although I am not certain that is the correct term. Some people insist that the correct term is "deciduous". Yeah, well, whatever...



This second photo shows a more evergreen plant right next door in an adjacent row that is fully green and comes from more evergreen stock plants. This kind of plant might look really bad in heavy stress conditions, and might even lose most of the outer leaves, but it will continue to grow as conditions improve- all the way to winter, and even after several very hard freezes. This type of plant has the ability to look really nice all summer if given the right conditions, and many of them can rebloom. Not all though!



So, if I have it right, "summer stress" is totally different than "summer dormant". At least for me, that is what I observe in my garden.