I need help understanding how evergreen daylilies grow in mild winter climates.
A continuously growing daylily keeps producing new baby leaves in the centre of its fan. The baby leaves grow longer so that there is a never-ending production of new leaves. The oldest leaves (the ones furthest out on the fan) would age, yellow and die slowly one by one but since the daylily is continuously producing new leaves the fan does not become smaller. The fan does not end up having fewer green mature leaves during the growing season.

Or perhaps an evergreen daylily takes a break and there are periods of time when new baby leaves are not produced and then after a while new baby leaves begin being produced again.

If you grow daylilies in a location with a mild winter climate (disregarding the effects of sudden cold snaps that may kill green leaves) how do your evergreen daylilies grow when there is no cold to affect them?

We live in Alabama and our evergreens do well. They get a little gummy in the winter they have been under snow before and when spring comes we just cut them back all bad off and they take off just like all the others. Now this summer we had some of our evergreens go summer dormant, and some of our semis go under too.

I am further south in Alabama than Roger, but I am once again reminded of how unobservant I am with my plants. I did take a few photos of dormant daylilies this winter, for some reason I was paying more attention to dormants, and not much to evergreens.
I did realize then that some dormants looked more like evergreens and some evergreens looked more like dormants. So due to how plants are registered and where they are grown it is hard to tell what is truely an evergreen.
So I will have to rely on a few photos in an effort to help.
'Palace Garden Beauty': Jan. 2019

Had to go back to 2018 to find this photo.

Here are a few more photos:
Here are a few more Evergreens:
'Chesapeake Bay', Jan. 2017

'Bali Watercolor:' Jan. 2017

'Freaky Good'

'Gossip Girl'

I think all of my established plants that are evergreen tended to shrink in size over the winter, but I have new seedlings that I swear looked to be continuously growing all winter (if you can call what we have had a winter).
Seedling bed:

Sorry not to be of more help.

Maurice, not sure if I can add more than what's been mentioned but more data is good, correct.

Again, just a bit farther south in Defuniak Springs, Fl... - I've noticed that although evergreen, my CVs enter a dormant period where no new foliage is growing. Or should I say, none that I've noticed. However, they look as lush and green as a fan producing new foliage.

The semi evergreen fans, I've noticed that the foliage begins to descend, but still several inches of green fan is present.

Dormants, fall completely back and only a, pardon the lack of proper terminology, but a nub of foliage is visible above the soil.

I've added a couple pictures of some of the different types here. All were taken this morning. Differences in foliage heights estimated to be between 4-6 inches. Shame on me for not using a measuring device for reference. Unless you were to reference the plant marker which are sticking just a couple inches above ground.

Sample Evergreen varieties


Sample Semi-Evergreen varieties


Sample Dormant varieties


The last photo reflects 'Mary Lena' a Dormant variety growing next to a Evergreen seedling.

Evergreens that go summer dormant

I assume that those evergreens actually lose all their leaves for a period during the summer.

@seedfork
Larry in your photo of Palace Garden Beauty from Jan 2019 I see some young leaves. They are shorter than mature leaves and nearer to the centre of the fans. However, I do not see any old mature leaves that have yellowed and perhaps dried and might be lying on the ground. Do you remove old leaves or are they perhaps covered by leaf mulch?

Do the leaves of Palace Garden Beauty tend to die during late August or September and new bright green leaves sprout then? Do only some leaves die then or many but not all? Or do new bright green leaves sprout continuously during your summer?

Might you perhaps have any photos of Palace Garden Beauty in June, July, August, September, October, November? I assume that it might bloom in May?

@GaNinFl

Yes, Stan, more data is good.

I've noticed that although evergreen, my CVs enter a dormant period where no new foliage is growing. Or should I say, none that I've noticed. However, they look as lush and green as a fan producing new foliage.

Do you know approximately when that period starts and ends? When the new foliage starts to grow at the end of that period does the old foliage start to yellow and die?

The first sample evergreen appears to not be in that dormant period (I see smaller than mature size leaves in the centre of some of the fans) . On the other hand, the second sample evergreen seems to show that it was dormant at that time (all the leaves look mature size and there do not appear to be any short new leaves in the centre of the fans).

Here in the North of England my daylilies just stop growing at the end of autumn and 'sleep' during winter, they don't go dormant in the sense of disappearing underground, they just stay as they were .

All leaf types generally act the same here, I have noticed no difference between evergreen, semi evergreen and dormant.

admmad said:

Do you know approximately when that period starts and ends? When the new foliage starts to grow at the end of that period does the old foliage start to yellow and die?

Unfortunately no, I suffer from non-observance about the period this occurs. So, that data point isn't recorded. However, I have only noticed within the past couple weeks the older leaves of the fan are beginning to yellow and die. I have removed most of this in a recent cleaning of the fans.

admmad said:
The first sample evergreen appears to not be in that dormant period (I see smaller than mature size leaves in the centre of some of the fans) . On the other hand, the second sample evergreen seems to show that it was dormant at that time (all the leaves look mature size and there do not appear to be any short new leaves in the centre of the fans).

Regarding these photos, please note that they were taken this morning. Also adding that our non-dormancy period, with our unusually milder temperatures this year (marking 81F yesterday), the Daylily's have really kicked into overdrive.

I went back out to look at the second sample, 'Indian Sky' and noted that it does show sign of new growth. Reflected in the below photo.

@Scatterbrain
Nikki do you mean that in winter all your daylilies are evergreen? That is they have normal length living green leaves that will still be living when it becomes warm enough in the spring?

Do you also mean that in the winter, young immature short leaves in the centre of each fan simply stop growing longer and will restart growing longer again in the spring and that this is the same no matter how the daylilies were registered (evergreen or dormant)?

admmad said:@seedfork
Larry in your photo of Palace Garden Beauty from Jan 2019 I see some young leaves. They are shorter than mature leaves and nearer to the centre of the fans. However, I do not see any old mature leaves that have yellowed and perhaps dried and might be lying on the ground. Do you remove old leaves or are they perhaps covered by leaf mulch?

I do mulch heavily, but it is more likely that I pulled the leaves off.

admmad said:Do the leaves of Palace Garden Beauty tend to die during late August or September and new bright green leaves sprout then? Do only some leaves die then or many but not all? Or do new bright green leaves sprout continuously during your summer?

I don't know.

admmad said:Might you perhaps have any photos of Palace Garden Beauty in June, July, August, September, October, November? I assume that it might bloom in May?

I did find two:
Sept.


Nov.

@admmad

Hi Maurice, yes they all have normal length, living green leaves, the immature leaves in the middle start growing again when it gets warmer. They all get a bit pale over the winter and a bit tatty where they get chewed by the ever present slugs and snails here but once a plant gets established in my garden there is no difference between the ones registered evergreen, semi-evergreen or dormant in behaviour.

The only difference is in the summer, occasionally ones registered as dormant take a year off flowering if we have a mild winter

@Scatterbrain Thank you.

Could you please name the specific daylilies registered as "dormants" that you have observed to take a year off flowering.

The reason I ask is that there is a common belief that "dormant" daylilies require a cold period to be able to flower. Research by a well known group of scientists working on flowering perennials for the greenhouse industry determined that was not the case, even for 'Stella de Oro'. Of course, they could not test thousands of different daylily cultivars, so it is possible that a rare daylily might require a cold period. Considering that Stella did not, and my understanding is that it does not do well in mild winter/hot summer climates, I would not expect any daylily to actually require cold to flower (vernalization).

On the other hand, plant species do not usually develop well when they are subjected to high temperatures. Now, I would not expect the U.K. to routinely experience sufficiently high temperatures but Arisumi tested one daylily and found that temperatures of 85F and 95F caused it to not flower while it was fine at 75F and 65F. At 65F of course it took longer for it to start flowering than at 75F.

Plant characteristics are strongly affected by temperature. Each characteristic may have its own base temperature (below which no development of the characteristic occurs), an optimum temperature and a maximum temperature. When plants experience high temperatures at particular times in development they may abort their developing scapes or abort developing buds or abort developing seed pods, etc.

High temperatures also affect pollen and the development of seed pods. Arisumi also looked a little at those effects. Arisumi used 'Purity' and it was registered in 1949. Selective breeding of daylilies has occurred for some 70 odd years, often in hot summer climates, since then so it is safe to assume that there are many modern cultivars that have higher optimum and maximum cardinal temperatures than 'Purity' has (especially tetraploids) . However, not all daylilies are hybridized in natural conditions in hot summer climates.

I would be interested in knowing which cultivars took a year off flowering for you.

I live on the Alabama Gulf Coast 1/2 mile from the water across the bay from Pensacola Fla. I don't believe any daylily here ever stops growing. I bloom seedlings (from seed to bloom) in 7-8 months, the two year old seedling seem to do more increasing in the winter than any other time and most of them bloom at their normal time (May and June). We have had much worse winters than this year but never seemed to effect the growth of the daylilies. This photo was taken yesterday 2-24-19 and there are very few dying leaves. Will try to get some close up photos today.

@admmad,

Hi Maurice,

The two in particular that did this for me were 'Pony' and 'Changing Latitudes'. I eventually removed them from the garden.

Here in zone 9b in south Louisiana they are green year around but the leaves get shabby & many lower leaves are yellow so mid February I cut them back to about 3" , apply Bayer 3 in 1 granules at base & a little epsom salt. By the time early bloomers flower, April 1st, I have a nice 10" to 12" lush green plant. About July 1st I trim most back again because of rust that is a problem in our humid climate, apply Bayer 3 in 1 again & this keeps them the rest of the year. I follow this same routine with my rebloomers & have not seen any issue with blooms & actually find the rejuvenation produces more blooms longer.

Scatterbrain said:@admmad,

Hi Maurice,

The two in particular that did this for me were 'Pony' and 'Changing Latitudes'. I eventually removed them from the garden.

They both do well for me and bloom every year. Of course, I have cold winters!

@admmad

It's an extreme example, but Matthew Kaskel had trouble getting most daylilies to bloom in Homestead, FL.

He started his program using some select Munson cultivars which would reliably flower for him, and through selection, developed a range which needed no winter rest. If I recall correctly, he was the first hybridizer to run his program on a 9-month bloom cycle, and anything which didn't bloom in one season was discarded.

His climate was tropical, and I think he was at peak bloom in March. Infusing dormant genetics into his lines was problematic. His solution was to have northern growers send plants to him in January/February, plants which had already experienced winter dormancy.

It's an extreme example, but Matthew Kaskel had trouble getting most daylilies to bloom in Homestead, FL.

It is very important to understand that evergreen daylilies also would not flower. Kaskel's observations on the problem were that early bloomers were better at flowering under Miami growing conditions and mid-bloomers were worse. Early bloomers experience lower temperatures while developing than later bloomers. It should also be emphasized that some evergreen daylilies hybridized in Florida were not necessarily any better at flowering in Miami conditions.

Those observations emphasize that daylilies are not necessarily adapted to extreme growing conditions. High temperatures are one factor that causes many plant species to not flower. Experiments by Arisumi determined that some daylilies may not flower at all when grown at 85F or 95F. He found around 75F to be an optimum temperature. I have used first flower open times and growing degree days and determined that for 'Barbara Mitchell' and 'Pardon Me' around 78F is a reasonable estimate of their optimum temperature for flowering.

@JamesT
Do you have personal first-hand knowledge of this solution? My information is that he used a different solution, when necessary.

His solution was to have northern growers send plants to him in January/February, plants which had already experienced winter dormancy.

I do not grow daylilies in my own yard, since I am more into succulents. But I see them in our common areas here.

Soil is heavily mulched here, to allow better moisture retention when the very long dry months come around. The HOA uses timed deep watering at night during the 6 to 7 months of zero rain fall and our humidity levels goes very dismal from 30% to 0%. Summer temps here hit a very dry 95F to triple digits for several weeks.

Then the mulch becomes protection for the base of the plant when it gets too cold at night in winter. Typically our overnight cold temps is around 30F to 40F, though there are times we do get some few hours of 20F to 21F. Every year is different, like this winter, we are more into rain, so it kept the areas overnight cold temps at the 30F to 40F range.

During Fall when blooms are over, the plants are trimmed down heavily, so it is bare during winter. If winter comes about rainy like it did now and not too cold overnights. the daylilies may send up new leaves right away. Our temps easily goes up anyways, so the moment daytime starts hitting 60F, these bulbs are quick to wake up, sending out their new leaves. Then by mid Spring it is the start of blooming time.

I see the gardeners apply some granular fertilizer in Spring, shaking them around the plants.

Our location is more inland, so our heat conditions during the dry months are more intense. It is different when these daylilies are in the Bay area, they have good coastal air influence, makes their bloom period much nicer and longer there with their pleasantly cool and sunnier conditions.