beckygardener said:Maurice - Thank you for taking the time to try to explain the "dormant" label on daylilies. I get what you are saying.
Becky, you are very welcome.
I KNOW I have dormants as described by the AHS. Almost always, after about 3 years, these plants disappear completely.
Can you please tell me the names of as many of those dormants (that are registered) as possible so that I can consider testing them.
I assume they just shrink little by little each year until they have decreased so much that they literally die. Is this typical of a true dormant daylily growing in central Florida climate or is something else possibly killing them?
A "true dormant", that is an endodormant that requires some amount of chilling to break its dormancy, may
act that way in locations where it does not experience enough chilling to completely break its dormancy. For those types of plants and in those locations they may not grow properly after winter. Some may not flower, some may not grow to their normal height, some may have deformed leaves, some may flower but have deformed flowers or fewer flowers, etc. In other words they grow abnormally if they do not receive sufficient chilling. Some buds may never sprout if they do not receive sufficient chilling. If that is the case then they may dwindle away with fewer and fewer buds each year. But that assumes that a large mature plant with many buds arrived from somewhere else where it did receive sufficient chilling and then is grown in a location where it does not receive enough chilling.
On the other hand there are other possible, completely different reasons why a cultivar that is registered as a "dormant" may not grow well in locations with warm winter climates.
There is a history of daylily hybridizers in warm winter locations choosing to hybridize more for daylilies that remain green during winter ("evergreen") and of hybridizers in cold winter climates choosing to hybridize more for daylilies that go completely down for winter ("dormant"). But there are other, possibly more important differences between locations that have mild winters and those that have cold winters. One of these is how hot it becomes during the summers; another may be how dry it becomes during the summers, etc.
Many years ago, Moldovan, who hybridized in Ohio, and Munson, who hybridized in Florida, began to swap cultivars. Apparently neither was happy about the way their registered cultivars grew in the other location. So Moldovan began to include daylilies registered as "evergreen" and "semi-evergreen" by Munson and Munson began to use daylilies registered as "dormant" by Moldovan. They were aiming to produce daylilies that were better adapted to grow in both regions rather than daylilies that were very well adapted to grow only in their own regions and poorly adapted to grow in other regions.
In general, a hybridizer can only easily produce plants that are well adapted to their own regions and conditions. Usually, the better adapted a plant is to its growing conditions the worse it is adapted to conditions that are different from those. The more different the growing conditions are to those where it was hybridized the worse adapted the plant is.
Typically, cultivars that are hybridized in the northern, colder winter areas will be better adapted to those conditions and not as well adapted to conditions in southern areas while those hybridized in the southern warmer winter areas will be better adapted to those conditions and not as well adapted to conditions in the northern areas.
Daylilies do not necessarily grow very well at quite high summer temperatures. Arisumi did some research on this. Unfortunately he only used one cultivar but it provides a good example. He used 'Purity'. All the AHS registration information for Purity (Traub, 1949) height 45in (114cm), season MLa, Diploid, Fragrant, YM1: Yellow medium self. [note the lack of registered foliage designation].
Arisumi grew 'Purity' at constant temperatures of 55F, 65F, 75F. 85F and 95F.
At 55F the plants grew slowly and did not reach maximum size during his test period.
At 65F the plants reached maximum size in 3 months. At 75F the plants reached maximum size in 2 months. At 85° and 95° the plants grew quickly for three to four weeks and then yellowed more and more. The older leaves dried and died more quickly than at the other temperatures.
He tested 24 plants at each temperature. All 24 plants grown at 75F bloomed. Only four of the plants at 85F bloomed and no other plant bloomed.
Constant temperatures of 85F and 95F were not optimum for 'Purity'. A temperature of 75F was better.
It is possible that daylilies that are registered as "dormant" or act "dormant" are better adapted to more moderate summer temperatures and are poorly adapted to hotter summer temperatures. That may be one reason why they may dwindle away in locations with mild winter climates. They could be better adapted to the moderate summer temperatures because they were hybridized in locations with fewer extreme temperatures or lower extreme temperatures during summer or because they were hybridized from parents that were hybridized in similar conditions.