Char,
I concluded from this data that the daylilies are much more consistent in the FFO dates than I would have guessed at. Good job of collecting and comparing data for the rest of us to look at. Thanks!

Sorry the dashes didn't work as well once I hit finished. The numbers were all in neat columns in preview mode with 5 to 6 dashes between.
The FFO dates are pretty consistent for me once the plants get past a 2 -3 year settling in period. Then when you take into consideration the HDD numbers it is interesting to see how they influence the bloom time too. If someone had similar records for a southern area it would be cool to compare those number findings to my northern ones. I'll have to remember to update the numbers for this year so we can see how the numbers compare to the previous years.
Glad you all found it interesting.

You guys are making me want to record all my FFOs this year. I have not done this since 2009. With the late season start this year, it will be interesting to see what blooms first.

Got CYBER ZONE in 2010 and I remember it bloomed first last year, but it has barely poked out this year. Waiting to see if another daylily beats it this year.

I have noticed that the daylily foliage on the east and south side of my house are taller than any other daylilies around my yard. Guess the microclimate comes into play.

Char,

Usually one relates flowering times to growing degree days; may I ask why you used heating and cooling degree days instead of growing degree days?

The expected result of using growing degree days and relating them to FFO, if there were no other factors affecting the variability of FFO, is that they would be more or less constant for each cultivar.

Maurice,
That is what I would have thought too. I was taking into consideration what was seen with the majority of the garden in relation to the HDD's. The years that were warmer in the 3700 -3900 range the plants bloomed earlier than the years in the 4400 - 4700 range which shifted my bloom weeks.... I was trying to figure out what this year could mean to bloom weeks while trying to figure out open dates for the garden and when peak may be, that is what led me to look into this.

I'm adding a photo of the word doc I have the records typed into. Hope this works better than the typed info of my last post. I'd be interested to know what you think based on this small sample.

Char, thank you for the data.

I have analyzed the data statistically (although I have broken a statistical 'rule' to keep it simple).
One of the things we should expect when analyzing different cultivars is that the measurements we make should confirm that the cultivars are different (they should be statistically significantly different).

I analyzed hdd - the cultivars are not statistically different for hdd accumulated to FFO.

I analyzed cdd - the cultivars are not statistically different for cdd accumulated to FFO.

I analyzed gdd - the cultivars are statistically different for gdd accumulated to FFO. The result indicates that the differences present among these cultivars would happen by chance only twice in a million times.

The conclusion is that FFO is related to gdd but not hdd or cdd in these cultivars. It is reasonably safe to assume that is true for daylilies in general.

On average, 'Destined to See' needs to accumulate approximately 988 gdd for FFO, 'Night Embers' needs to accumulate 1020 gdd, 'Primal Scream' needs to accumulate 1110 gdd, and 'Itsy Bitsy Spider' needs to accumulate 739 gdd. However, there will be variability in those values from year-to-year, as there commonly is in characteristics measured on living organisms.

That is great work for the rest of us. Am I correct in my understanding then, that daylilies could be better rated maybe by gdd than by early, midseason and late etc.?

What is gdd again?

Gleni,
http://agron-www.agron.iastate...

I guess most northern daylily growers are familiar with this term, but it was the first I had heard of it "Cold Morning Opening". I had no idea this was a recognizable trait in daylilies.
http://huben.us/daylily/Extend...

Seedfork, I have seen Pat Stamile use that reference to some of his daylilies down there in FL.
http://www.distinctly.on.ca/fl... Go to "Clear Mountain Morning".

I see in the description emo,"early morning opening" further down I do see the reference to opening on nights with temperatures down to forty. So I guess that is an indication of the actual temperature referenced when speaking of a "cold morning opener". I just had never considered the fact that a certain temp. was required for the daylily to open, but it makes perfect sense.

Thanks Seed. I am all eyes.

I agree CDD doesn't seem to factor in and basing FFO on two different "warm" base temps (65 and 50) is confusing. HDD either stops accumulating or slows down by bloom time making those numbers difficult to relate to an average for FFO. HDD does show the difference in FFO, when there is a lower HDD number FFO's can be as much as a week earlier than in years with higher HDD's. What is interesting for a majority of the record in the years with higher HDD is although the cv's FFO'd later it took less GDD's to reach FFO.
I realized those average GDD's as well and it would make sense that FFO is related to an accumulation of GDD's. However, if those are the ave GDD's for these cv's to reach FFO how do these numbers figure into the equation.

GDD's for Sanford Florida, from 1/1/14 to 3/26/14 (today) they have 1044 GDD. If the average GDD's were true for FFO then these cv's should all be blooming or about to within the next week and Sanford, Fl. would be well on their way to midseason or peak bloom now.
Destined to See (ear/mid) ave. 988
Night Embers (ear/mid) ave. 1020
Primal Scream (mid/late) ave. 1110
Itsy Bitsy Spider (ear) ave 739
There must be something else that figures into FFO in addition to ave GDD for each cv?

I couldn't use GDD's for what I was trying to figure out a week ago, we have none yet this year. We not only need to warm up, it was -3 yesterday morning, but we also need to melt almost 3 feet of snow covering the garden and thaw the ground before the plants even think about growing. The only thing I have to work with currently is HDD numbers and the HDD, FFO dates and years do show a relationship I can see. It will be really interesting to record the FFO, HDD and GDD for these 4 cv's this year.

Plants need a certain temperature to be reached before they can start to grow. Then, because they cannot regulate their temperature the speed at which they grow is determined by the temperatures they experience during each day and night (plus all sorts of other things such as the actual intensity of light, how they were fertilized, watered, etc). But what tends to be the most important is the temperature. Each plant species has its own "base" temperature - below that temperature it does not grow (or grows so slowly that it makes little visible growth). The base temperature for corn/maize (Zea mays) is 50F; the base temperature for wheat is 32F; Many perennials are assumed to have a base temperature of 40F or 5C (which is 41F).

Since different species have different base temperatures, growing degree days (gdd) can be calculated with different bases. If my memory is serving me correctly I once calculated an approximate base temperature for daylilies as 42F so gdd that are calculated with base 40F or 5C should be ok.

Heating degree days are often calculated from a base temperature of 65F.
If the average temperature of a day is 65F then that day's hdd is 0 but its gdd (base 40) is 25. If the average temperature for a day is 40F then its hdd is 25 but its gdd is 0. If the average temperature for a day is 32F then its hdd is 33 but its gdd is 0. If the average temperature for a day is 73F then its hdd is 0 but its gdd is 33.

When the average daily temperature in a location is between the base temperature of hdd and the base temperature of gdd the two will be related, but outside of those temperatures they will not be related. Hdd may provide an estimate of the gdd in some locations for some periods of time but gdd should always be more accurate.

When one tries to use either gdd or hdd to calculate bloom time one needs to be sure that the start date used for the calculation is appropriate. Plants do not have a January 1 start date for their growth It becomes difficult to pick the appropriate date to start accumulating gdd. A location may have 20 days of average temperatures above 40F and the daylilies start to grow but then one day of below 32F may knock their growth back and they have to start again when the temperatures rise above 40F. Or one day may actually have quite a high average temperature but its low was much below 32F and that set the plants back but is not visible in the simple gdds (one would have to look at the actual minimum temperatures rather than use the gdds calculated by locations such as the weatherunderground). So yes there are always other factors involved. Gdds are simply calculated from average daily temperatures, but those are not entirely accurate - a more accurate calculation would require hourly temperatures for each hour of every day and the appropriate equations relating growth to temperature for the particular plant species.

Bloom is starting about now in some parts of Florida, isn't it?

Earlier in this thread I indicated that there would be a general consistency to flowering dates but that many factors influence flowering. Two locations with exactly the same gdds will not necessarily have exactly the same FFO for the same cultivar. Even cloud cover can influence flowering date, along with all the plant 'nutrient' factors, etc. I have several clumps of the same cultivars planted at opposite ends of the rows in the same field. They never have FFO on the same day yet as far as I know there are no differences between their locations and the clumps are about the same sizes, etc.

"Plants do not have a January 1 start date for their growth"
I have seen a chart showing the different GDD base temps for various plants and wondered if we had one for daylilies, 42F I'll have to remember that. They do show a general consistency in bloom time/season and the garden has a definite flow from beginning to end, but with so many factors to consider in FFO pinpointing exacts seems near impossible. I also compare FFO's during the season with a friend 3 hours south of me. It is amazing sometimes the difference between my FFO for something and his, sometimes mine bloom first.
There have been a few reports of folks seeing scapes starting and a few early blooms in the south....we still have a long way to go.

Char, please do not put too much faith in 42F or what I show next. It is not based on a large enough sample size and it was estimated from observations not from a designed experiment.

Plant growth tends to look like this-


Plants have a minimum temperature, an optimum and a maximum temperature for growth. Simple growing degree day calculations work best when temperatures are between the minimum and the optimum. That is the part of the curve that is approximately a straight line. When I did my calculations the results fitted best when the straight line was through 42F and 78F, but 40F and 80F were almost as good. So, since many perennials are thought to have a base temperature of 5C it is probably better, if one must, to use 40F as the base and 80F as the optimum.

Some may have read or heard the idea that for every USDA zone change from the South to the North (in the East) a daylily loses approximately 5 buds from its bud count. The problem is that USDA hardiness zones are more or less based on average minimum winter temperatures. Those may affect whether a plant survives winter but they do not really affect how it grows during the season. Growing degree days tends to be a better fit for characteristics which depend on growth, such as FFO and bud counts.

Plants show what is called phenotypic plasticity. They cannot move from poor environments to better ones, like an animal can, so they make the best with what they have. They change depending on the conditions where they are growing. They adapt to their growing conditions. The same daylily cultivar grown in Florida will not have exactly the same characteristics as one grown in Maine. The idea above suggests that it will have fewer buds in Maine; that usually means the plant will be smaller in Maine (not necessarily, but possibly in scape height, possibly in number of scape branches, possibly in width of the fan at soil level, perhaps in number of leaves or width or length of the leaves, etc.) A plant that adapts to a shorter growing season (which is more or less what fewer gdd usually tend to mean) by producing fewer buds may also adapt by blooming a little earlier than a plant that adapts to a longer growing season (more gdd). I think this is the case. I have used FFO dates from a number of different gardens from South to North for the same cultivar to examine this. There is a tendency for plants of the same cultivar to bloom (FFO) with fewer gdds the further North they are grown. Of course that is also true if one replaces gdd with latitude. So a plant that might not have FFO until 2200 gdds in Florida might have FFO with 2100 gdds in Vermont in the same year and might have FFO with 2000 gdds in Ontario. I only had one cultivar to use for the analysis so there is not much confidence that it is real. The cultivar was 'Barbara Mitchell'. If any one has collected FFO dates for one or more years and is willing to provide that information and their location I might be able to do a second analysis using recent data.

A lot of changes in my garden this year, my older ones have been dug up and relocated; ones bought in the fall are residing in pots or horse troughs. My FFO was Spacecoast Color Scheme - registered as EE and residing in a horse trough. Second and third FO are seedlings from pollen parent, Wonder of It All, followed by seedlings from pollen parent, Katahdin. Both of the next set of flowers reside in a cottage garden type place with about half day of sun. SC Color Scheme was about 4 weeks ahead of these others.

I'm certain that not much can be learned from my order of bloom this year but at least my EE bloomed first.

Interesting article and I love data.