CaliFlowers said:Maurice, could that emergence from dormancy be a matter of timing?
In your climate, by late December it seems as if daylilies grown outside would have already experienced quite a bit of both photoperiod (assuming it exists) and/or cold-induced dormancy, and when introduced to warm conditions, they would begin to grow, and once doing so, the hormone cycle set into play might overpower the photoperiod effect.
I have also looked at growth and dormancy earlier in the year. I have brought dormant daylilies inside in both November and October. In all cases and all cultivars I have looked at so far the plants start right back into growth and continue even though they are experiencing short days (biologically actually long nights). They do not grow very quickly but they do break bud and grow.
What I've noticed here regarding photoperiod-induced dormancy is on the other end of the growing season. Despite fair temperatures, (not even light frosts at that point) many dormant daylilies are down to hard crowns by Thanksgiving. This is what led me to think that photoperiod was involved. What do you think is going on there? Is it a matter of the plants having produced a "season's worth" of leaves and blooming stems, triggering a rest period? Might it have something to do with the plants being sensitive to increasing day lengths in January and decreasing day lengths in autumn? Put another way, could it be that the plants are able to sense that each day is longer than the last, and that alone is enough to maintain a growth cycle?
It is possible that daylilies respond to the direction of changes in day length (biologically actual responses are to the night length). I don't think that is what is happening.
Plants adapt their growth to their environmental conditions. Unfortunately daylilies appear to be very adaptable in that manner. I have done a number of tests with 'Ophir' looking at its growth patterns. I have a bed with a row of 'Ophir'. The bed has not received any fertilizer in 20 years and it has never been watered (it receives only rainfall). It is weeded only once every few years and the plants in the bed had never been divided (almost natural wild growing conditions). Most of the 'Ophir' plants in that row produce a scape and stop producing new leaves at the same time. The scape appears in June and typically no new leaves are grown after that. Leaves that had been produced before then continue to grow and become longer. For some of the plants and in some years new leaves are produced after the scape appears. In those cases they stop being produced in mid-July. It tends to be the juvenile fans (that did not produce a scape) that continue to produce new leaves. Even though no new leaves are produced the crop of leaves survives until late October or early November. By then it has yellowed, fallen to the ground and is in the process of dying and drying. The bud that will be next year's fan is present underground in July. It slowly becomes larger but does not appear above ground before snow falls. I have brought fans of 'Ophir' from that bed inside as early as Oct 15; they sprouted from their buds and grew. I dug fans from that row in July one year and tested several groups. One group I simply left as is with scapes and leaves. A second group I removed the scape. A third group I removed the leaves and a fourth group I removed the leaves and scapes. All groups were put into water. The groups that had no leaves sprouted their buds first. Unfortunately as time passed the original leaves on the two groups (1 & 2) died (water was not enough to keep the fans healthy) and they also sprouted new leaves. However the conclusion appears that the presence of green leaves kept the bud from sprouting more than the presence of a scape and flowers.
The 'Ophir' in that bed have a growth pattern that appears to be dormant. 'Ophir' is registered as semi-evergreen and as a rebloomer. In that bed, with its dormant growth 'Ophir' would not be able to rebloom. However, Florida and California hybridizers indicate that nearly all cultivars rebloom in their growing conditions. So I changed the growing conditions for 'Ophir' for my next test. Some fans were planted in a raised bed of fresh soil that had been turned over and the sod rotted down and incorporated. Other fans were planted into a fresh bed and fertilized with plenty of nitrogen, watered and weeded. It took a year of growth before any of the fans produced scapes. In that second year 'Ophir' had a different growth pattern in both new locations. It produced new leaves all growing season and rebloomed.
I also tested 'Wynnson', a registered dormant by placing fans in water and observing whether new leaves were produced (bud break). It acted like 'Ophir'. However, Wynnson does (usually) behave differently from 'Ophir' in the autumn. Some of its fans break bud in September even when growing under quasi-natural conditions. However, it also continues to produce new leaves when grown with fertilizer, watered and weeded - like 'Ophir'.
'May May' is registered as a semi-evergreen rebloomer. Here it has lost almost all of its leaves; it did rebloom and it has broken bud with new fans and fresh leaf growth appearing. It is the only cultivar in many hundreds that I have noticed senesced (its leaves yellowed and died) so early this year. There is one other that tends to senesce early and that is a Siloam.
What I think is happening involves both the growth of the fan and leaves, the aging of the leaves and their effect on bud break and the production of a scape.
The growth behaviour of daylily fans is probably different depending on whether the fan is juvenile or mature. Mature fans are presumably large enough to bloom in their growing conditions while juvenile fans are not. If size is what determines the ability to flower then it may not be size of the fan; it may be size of the leaves, total photosynthetic area of the leaves, size of the growing point or shoot apical meristem (SAM) and whatever it is will be dependent on growing conditions. I have looked more at the growth patterns of mature fans.
A mature fan has one active growing point (SAM). It produces leaves and then switches over to producing the scape and flowers. When it does so it is finished and new leaves can only be produced normally by an axillary bud breaking/sprouting. Leaves can only live so long. They have natural lifespans and when they get to be a certain age they will die. They can also die due to environmental conditions. The leaves of many perennial plants produce compounds that prevent axillary buds from sprouting. Whether the leaves do prevent axillary buds from sprouting also depends on the environmental conditions. It is also possible that photoperiod changes cause leaves to die.
In some daylily cultivars and under some growing conditions when the SAM produces the scape an axillary bud will break and new leaves will be produced. The end result is that the fan may produce new leaves continuously throughout the growing season or there may be a short break in new leaf production that is more or less not noticeable.
In other daylily cultivars and under some growing conditions when the SAM produces the scape no axillary bud breaks and new leaf production stops for the growing season. In some of these cultivars when the leaves start to die (usually in the autumn) and under some growing conditions the axillary buds break and new leaves are produced that year/growing season. In some other of these cultivars when the leaves start to die and under some growing conditions the axillary buds do not break and no new leaves are produced visibly above ground.
I will be bringing some daylily plants inside this winter to test whether short days/long nights cause leaves to age and die.
