Sue, the foliage shrinks down to 3-4". If you look at the pictures I posted earlier, that's what you will see. Probably in the fall, tall leaves are replaced by short leaves. I'm constantly removing dead leaves, so I can't attest to that. What I do know is that I have daylilies that over the winter will have 3" leaves above the ground. They sit there even if I fertilize them with cal mag (rocket fuel as Dan Trimmer calls it). They never, ever go underground. Remember, down here "cold" means 40 degrees or maybe 38 degrees at the lowest. With the short days of winter, these plants do what they must and they won't recover until the days get substantially longer. Maybe it's just a reaction to the amount of light in a day, but the evergreens don't respond to that, either. All I know is that most people who grow daylilies are backyard gardeners and the science means nothing to them. What matters is that a grower's description matches the growth exhibited by the daylilies they just bought.

Sue, semievergreen is a sliding scale. At one end is evergreen characteristics and at the other is dormant characteristics. In FL these characteristics are dramatically different. We can really, really tell the difference. I have never had a daylily go underground in the fall, but then, I don't knowingly purchase dormants.

When I'd looked at the pictures originally I'd thought they were taller than that, I guess looking at the other plants beside and now knowing that's what you meant, I can get a better idea and now I see what you mean. I was trying to fit what you were saying in with the AHS registration instructions:

Evergreen (ev.)
These daylilies retain their foliage throughout the year. In the north, these plants over
winter as a mound of frozen pale green foliage. Evergreens may resume growth during a
mid-winter thaw in mild climates.

Semi-evergreen (sev.)
The foliage of these daylilies dies back nearly to the ground in very cold climates. Some
green will be seen near the base. Generally, semi-evergreens wait until spring to resume
growth.

Dormant (dor.)
These daylilies lose their foliage completely before or shortly after frost and over winter
with pointed foliage buds, usually just beneath the soil surface. Dormants will resume
growth in spring.

Since I grow many seedlings, I can tell you that I have some disappear every year. One of my favorite seedlings from last year has completely disappeared over our mild Winter. I fear it is a goner. It has dormant genetics in it's pedigree. It's siblings have not totally disappeared and are sending up new foliage. (I know each seedling is unique.) If they are heat sensitive, why don't they die or drop their foliage in the Summer/Fall? Why do they typically disappear during the Winter months? I had a very mild Winter this year. It never got into freezing temps. Any cold temps were only overnight or early morning and then the temps warmed up once the sun started shining. Very brief temps in the high 30's for only a few days this Winter.

If a daylily plant is deciduous, when would one expect them to send up new growth? Early Spring, late Spring, Summer? Or as I fear .... never. They may have died.

@Hemlady,
Your rule of thumb is as good as any other. Each grower can only classify daylilies as they see them grow in their own location and under their own growing conditions. They cannot know whether the growth pattern their daylilies show will be consistent in all locations or whether it will vary in different locations.

Here is a specific example. The ditchlily 'Europa' loses its leaves and has an underground bud here, and for Stout in New York and for Watkins in Gainesville, Florida where it had a long rest. Stout took Europa inside in November in New York and within a few days it started to grow and later flowered and continued to grow. It does the same thing when I bring it inside here in the autumn. So it loses its leaves makes a bud and stays underground because of the cold outside. As soon as it is warm enough, it grows. Even the mild cold of Gainesville is enough to send it scurrying underground and forming a bud. But give it between 60F and 72F, even with the short days of a New York winter and the low light intensity of a northern winter and it happily grows. So, in a greenhouse, where it experiences a winter that is warmer than Gainesville but not hot it does not stop growing. It would be registered as "dormant" here, in New York and all the way south to Gainesville, but it would be registered as evergreen anywhere that the winter temperature stayed between 60F-72F. It is an ecodormant. It stops growing, loses its leaves, sets a bud and stays under ground for a long rest only because it is cold enough (even in Gainesville). Where it is not cold enough it is an evergreen. Even after it has set a bud, etc. because of the cold, all we need to do to get it to grow again is to make it warm.

The registration categories and the actual growth patterns of daylilies cannot be relied upon to be consistent. It is not like registering a plant as having a yellow flower and knowing that no matter where or how that plant is grown it will have a yellow flower and it will never have a red flower. You can register a daylily as a "dormant" because it acts that way how and where you grow it but there may be other locations where it acts completely normally and just like an "evergreen". Biologically it is neither - it simply reacts to its growing conditions or environment and responds as well as it can.

There may be some daylilies that rather than ecodormant are endodormants. I will keep looking.

beckygardener said:Since I grow many seedlings, I can tell you that I have some disappear every year.

Seedlings can disappear for many reasons. Some disappear here over winter.

One of my favorite seedlings from last year has completely disappeared over our mild Winter. I fear it is a goner. It has dormant genetics in it's pedigree.

One would have to watch such a seedling reasonably carefully and notice how it was growing from the time it sprouted to get clues about what is happening.

It's siblings have not totally disappeared and are sending up new foliage. (I know each seedling is unique.)

One needs some clues about its growing behaviour before and as it disappeared. Is it not possible that its leaves simply aged and dried up as they would when they had reached their expected lifespans? Or did they yellow and die very rapidly?

If they are heat sensitive, why don't they die or drop their foliage in the Summer/Fall?

When were the seeds planted? When did they sprout? How many leaves did they grow? When did they stop producing new leaves? When did the leaves start to yellow and die? I would normally expect a daylily that is having heat problems to become summer dormant (lose its leaves early during the heat) and then grow a new crop later. However, there is a catch. A researcher has looked at the death of seedlings. If they do not grow large enough they are apparently unable to form a bud. Those apparently die. Seedling death over winter is related to seedling size entering winter. If a daylily seed sprouts before the heat of the summer and then loses its leaves due to summer dormancy and it is not big enough it may not sprout ever again.

Assume that your seedling has quite normally grown and then lost its leaves due to their age and set a bud and stopped growing. Did its siblings stop growing? Not whether its siblings lost all their leaves or just some of them. To know if a daylily is dormant one needs to look in the centre of the fan of leaves. If one sees a short leaf then come back every few days and check whether a new short leaf appears on the other half of the fan opposite from the previous new leaf. As long as new short baby leaves keep appearing every few days assume the meristem is not dormant. When no new baby leaves appear for a longer period (and the temperature did not become too low) then assume the meristem is dormant (in both cases one may be incorrect but it is the best one can do). After a certain time the old mature leaves will die. If no new baby leaves have appeared in the meantime then the bud will be completely underground. That is normal behaviour. After the passage of sufficient time new baby leave should start appearing again.

If the fan does not sprout and you check the spot where it was last seen what do you find?

Each daylily will have its own time when new leaf growth will appear - one cannot predict. In Gainesville Watkins indicated that Hyperion did not appear until late in spring, Mikado appeared in early March. In Texas, Hyperion appeared in early March.

Since soil temperatures appear to be a significant factor in plant growth, I'm wondering if there's a standard procedure for taking soil temperature readings. Soil temperature is a spectrum throughout the root zone,very hot at the surface, and a good deal cooler 9-12 inches deep.

This makes me wonder about Arisumi's results where the entire root ball as well as the above-ground parts of the plant were essentially the same temperature. Roots have probably not evolved to tolerate such high temperatures, perhaps leading to the poor growth and performance seen in the higher temperature ranges—temperatures which are not uncommon in many parts of the US.

In Arisumi's experiment, were the plants held at the stated temperatures continuously, or was there a day/night swing?

Growing in raised beds would have that problem too.

Maurice - The seedling did not die right away. In fact, it appeared to go dormant and then produced some small leaves, but then those disappeared, too. I've no idea what happened. But the older leaves did turn somewhat yellow and drop unlike it's siblings. The small leaves just fell away from the plant. Perhaps root rot?

Something did occur to me though .... it bloomed for the first time this past Spring. I forget how many blooms. I think 6 or so. I pollinated all the blooms and got pods from each. That may have stressed the plant too much. I did not hybridize it's siblings as much but 1 or 2 blooms.

I'm learning. Before, it never occurred to me not to overdo the hybridizing efforts on young seedlings. I probably should have only hybridized 1 or 2 blooms last season instead of all of them. That takes too much energy away from such young seedlings.

It's a shame. I really loved the bloom on this seedling.

As far as soil temps, most of my daylilies are in raised beds. I wonder if I should probably invest in a shade cloth to place over those beds during the hottest part of the summer?

If the leaves fell away, that does sound rather like it could be a rot of some kind. When they are "dormant", that is deciduous, the leaves don't immediately detach at the base even if you tug on them.

The temperature in a raised bed is going to be higher than for plants in the ground so a shade cloth may indeed help, Also dark coloured media in the bed will cause a higher temperature than a lighter coloured medium. From your pictures, though, yours doesn't look excessively dark.

Sue - Yes, that it what I really think happened with this particular seedling. Unfortunately, it is the pink blooming seedling in my avatar. Sometimes, your best efforts just don't work out.....

I keep going back over this thread and re-reading all the cultivar suggestions that everyone posted. Thank you to each of you for your lists .... however large or small.

The dormancy issue has always confused me. Since I have high summer heat here (for many, many months) .... if dormancy is more about heat dormancy ... then I can certainly believe that. And if heat stress is more likely to reduce or even kill some cultivars .... then it will truly be trial and error in my gardens. It will be interesting to see which cultivars tough it out and do well. I have been very fortunate to receive cultivars for free or very cheap, so I'm lucky in that respect. For me, that is one of the reasons that I do NOT seek to purchase expensive daylilies. It becomes a waste of money very quickly otherwise.

Something else that I am wondering about ... do cultivars survive better if there is a clump vs. a single or even double fan? Or does it not make any difference the number of fans of the cultivar if heat stress is a factor.

I will say the cultivars in the raised bed that I pictured in a previous post on this thread are really producing some nice foliage. I am also seeing rust on a few of them. Some were bonus plants and their rust resistance is unknown. (I may know soon which ones have the resistance and which don't.)

The one thing I've yet to see is a large clump of a cultivar or seedling. A few of my seedlings may produce a nice clump this year. I hope so! I often think that a clump vs. just a couple of fans is much more likely to survive the summer heat. But that may not be true.

One more question .... is there anything that can be added to the soil to help the daylilies better handle heat stress? Compost? Micro-nutrients? Lots of water during the hot months?

I do believe a Shade cloth might also help. I will have to figure something out concerning that. I do have an idea to make a pvc hoop cover for the raised beds. But my other issue is do I really want that in my garden. Maybe it would be better to see which plants can handle heat and survive and thrive. I sometimes read that gardeners have a cultivar or seedling that toughs it out with ease during a hot and sometimes dry summer. I might also be able to provide some shade by moving some potted plants around near the beds to give some shade.

Becky, at least you have seedlings from it. It's also somewhat possible it may come back eventually. I would say that an established clump would have less of a problem with heat stress because there is more foliage to shade the soil. If it's growing with a lot of other larger clumps then the ground will be even more shaded.

beckygardener said:One more question .... is there anything that can be added to the soil to help the daylilies better handle heat stress? Compost? Micro-nutrients? Lots of water during the hot months?

Adequate nutrition would help but without any testing you don't know what might need adding. I wouldn't add micronutrients without knowing which, if any, you need because they can be toxic if added in too large an amount and they are needed in such small amounts that the difference between adequate and toxic is also small. The soil pH also significantly affects the availability of nutrients and for micros the lower the soil pH the higher the availability in general (availability can get too high in fact, if the pH goes too low). The soil pH can safely be lower in soilless media than mineral soil though.

The major nutrients are also important in heat stress, you need sufficient N and K but not overdo the N. If you were to use something like a complete NPK fertilizer with micros it should cover you (again with the caveat that absent a soil test you don't know the ideal ratio).

In plant nutrition the "law of the minimum" applies. If even just one of the essential nutrients is deficient the plant will not do as well as it could.

With water, adequate water will help with heat but you also don't want to over-water. It's especially important to take humidity into account because if humidity is high the plants don't take up as much water as if it was dry, or windy. Also you don't want to frequently water just the soil surface because it causes the roots to be shallow also and roots near the soil surface would get the most heat. You need to water deeply and then not water again until the soil at root depth is getting dry. Watering deeply enough can take a lot more time than one might think, I learned that the hard way.

Sue - My bed is filled with some top soil mixed in with mostly pine fines. I use fish emulsion, MiracleGro (liquid), and a little bit of epsom salt mixed together in a watering can and hand water/fertilize the raised beds. Later, I also add alfalfa pellets and Osmocote time released fertilizer pellets. I am getting ready to add the Osmocote today. It should last through blooming season (I hope). Every once in a while I will add a couple drops of Superthrive to the MiracleGro water.

Using pine fines as the planting medium, the watering does go all the way down into the roots. I water thoroughly right now about once or twice a week depending on how warm it is. I really love pine fines for planting medium. I think others here also use it.

Becky, there are several different Osmocote products, are you using one with micronutrients? Just curious, why use so many different things?

It's not possible to know what nutrient balance you naturally have in your top soil plus pine fines without testing. Soils can vary. I'm assuming the mix contains enough calcium naturally because that isn't in fertilizers generally (nor is magnesium but you're adding that with the Epsom salts).

I use the Fish Emulsion, MiracleGro, and Epsom Salt mixed together in Winter, because I don't want to fertilize too much in case we get a freeze. I add the Osmocote in Spring and yes, it does have the micro-nutrients in it.

I did add lime to the pine fines when I filled the bed. The new daylilies seem to be doing well. (Except for the 2 that disappeared over the Winter. I am wondering if I may have planted them too deep and they developed root rot.) Though Raspberry Beret seemed to struggle here since I received it and potted it up. It is also a rust bucket. I'm not too broken-hearted about losing that one!

In just a week, the foliage on the daylilies in the new bed has really put on some growth. I think the MiracleGro fertilzing I did perked everything right up and sent the cultivars into grow mode. No scapes yet. I think I had my first scape on a seedling last year at the end of March. I was expecting scape formation earlier this year because we had such a warm and wet winter. But each cultivar and seedling has their own natural timeline, I suppose?

Arisumi's observations are important because they indicate that daylilies respond to temperature in the same manner as all other plant species. They have optimum temperatures. They suffer from heat stress. Each daylily cultivar will have its own optimum temperature for growth. Some daylilies will have lower optimum temperatures than others. Arisumi used only one cultivar; its specific optimum is not the important point. {Using first flower opening dates as a measure of growth, I calculated that 'Barbara Mitchell' would have an optimum temperature around 78F.} The natural habitats of daylilies are varied. For example, many natural populations of Hemerocallis dumortierii are found in mountainous regions at altitudes of 4000 to 8000 ft. Others are found at sea level. The optimum temperatures for growth of the different populations will differ. The optimum temperatures for growth of northern-bred daylilies will on average differ from the optimum temperatures for southern-bred daylilies.

Daylily hybridizers cannot select for daylilies that will grow well in other locations and growing conditions unless they grow their plants in those locations and conditions. They would have to choose only plants that do well in all their locations to use as parents. Otherwise, over time, each hybridizer will inadvertently produce daylilies that grow best in their own location and conditions. Those will be the optimum conditions for their introductions. Thus, hybridizers who produce daylilies in locations with frequent high summer temperatures will produce plants that can grow acceptably well in those conditions. Hybridizers who produce daylilies in locations with infrequent high summer temperatures will not be able to produce plants that will grow as well in those locations with frequent high summer temperatures.

Moldovan [Ohio] learned about this. He said, "When I started daylilies, I grew northern varieties because I'd heard that southern evergreens would die for us. So I bred dormant with dormant. I remember sending some of my initial seedlings down to southern Florida to be grown and tested to see how they'd grow, and they didn't! I was crushed, of course. I went down there and said, "What am I going to do?" I started a program of crossing northern things with southern
things."
From the Daylily Journal about Steve Moldovan and Bill Munson [Florida], "Because Steve became a close-working daylily friend, Bill's stock traveled north.
Every year over the course of three decades the two of them spent considerable time at peak bloom season in each other's gardens talking, photographing, evaluating, and sharing thousands of seedlings."
What they were doing was moving from having introductions that grew very well in their own conditions and poorly in the other conditions to having introductions that grew at least well in both conditions. There will be many differences in growing conditions between northern locations and southern locations - temperature is the most obvious and plants suffer from heat stress at high temperatures.

Maurice - what you wrote is really starting to make total sense to me.

That makes sense that it is more about crossing southern bred with northern bred cultivars to produce intros that may often grow well in different climates.

It doesn't impact the seedling as to where it was originally sown and grown? It is more about pedigree genetics, correct? I ask that question because I have received plants as well as seeds from a northern zone (not dayliles) but other plants like Brugmansias, salvia, and herbs. The seed grown plants seemed to tolerate the heat a bit better. I assumed that was because the heat tolerant seed grown plants were the seedling survivors and the other seeds didn't. So the toughest seeds went on to produce plants that grew and survived better than a plant or less heat tolerant seed did here in my garden.

I am getting over the misconception that all daylilies are tough and can grow anywhere. That couldn't be further from the truth apparently.

beckygardener said:It doesn't impact the seedling as to where it was originally sown and grown? It is more about pedigree genetics, correct?

Where a plant is originally sown and grown (and how it was grown) can impact many of its characteristics for different lengths of time. Plants can and do adapt to their environment. Most of the changes brought about by such adaptation is relatively temporary. Long term growth, etc. relies more on the genetics.

The seed grown plants seemed to tolerate the heat a bit better. I assumed that was because the heat tolerant seed grown plants were the seedling survivors and the other seeds didn't. So the toughest seeds went on to produce plants that grew and survived better than a plant or less heat tolerant seed did here in my garden.

That would also be my starting assumption.

Maurice, I thought Ken raised an interesting question. When I looked at Arisumi's paper it does not appear he lowered the temperature at night. This could affect net photosynthesis (although I have a feeling I read somewhere that this is not necessarily now thought to always the case, it used to be we were told that night temperatures had to be lower so that respiration rate didn't equal or exceed photosynthesis otherwise the plants would decline or at the very least not grow).

In nature the night temperatures are almost always going to be less than day temperatures. Anyway, disregarding that, are you basing your assessment regarding detrimental temperature on air or soil temps since, as Ken surmised, with the potted plants in Arisumi's study they would both have been the same 24/7?

Several articles note different effects between high air and high soil temps. Here is one abstract (non-daylily) for example:

"High air or soil temperature is a major factor limiting growth of cool-season grasses during summer months in the transition zone and warm climate regions. Knowledge of how cool-season grasses respond to differential high air and soil temperatures would facilitate our understanding of heat tolerance mechanisms. The objectives of this study were to compare the influence of air versus soil temperature on turf quality, physiological activities, and root growth of creeping bentgrass (Agrostis palustris Huds. cv. Penncross), and to investigate whether shoot and root growth could be improved by reducing soil temperature at high air temperatures. Shoots and roots were exposed to four air/soil temperature regimes (20/20, 20/35, 35/20, and 35/35°C) for 56 d in growth chambers. High soil (20/35°C) and high air/soil (35/35°C) temperatures reduced canopy photosynthetic rate (Pn), turf quality, and the number of roots. High air/soil temperatures also reduced photochemical efficiency (Fv/Fm). The adverse effects of high air/soil temperatures were more pronounced than either high soil or air temperature alone for turf quality, Fv/Fm, Pn, and root growth. High soil temperature was more detrimental than high air temperature. Lowering soil temperature at high air temperatures (35/20°C) increased root growth, canopy Pn, Fv/Fm, and turf quality, compared with high soil temperature at low or high air temperatures (20/35 and 35/35°C). The results demonstrated that roots mediated shoot responses to high temperature stress in creeping bentgrass, and that reducing root-zone temperature could help maintain quality creeping bentgrass under supraoptimal ambient temperatures."

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