is summer dormancy real?

[John Polka]

Is summer dormancy a myth? Or fact? If true... How do you tell if a hosta has entered summer dormancy? If a hosta has entered summer dormancy, is it done growing for the season.. or will it continue to grow when it cools off? Sorry to copy thread idea from gardenweb...was hoping to hear Chris's thoughts on the subject...
John

[ogrefcf]

I read and was thinking the same thing John. Curious about it also.

[guardbear]

Hi All

I also am most interested in Chris' experience with this, and hope to get some specific information. I was thinking this may be at least partially why they don't water their hostas above 90 degrees, but wait to drench them when temps cool down . I think that plant dormancy of hostas is real -- but I don't think that ALL hostas, under ALL conditions exhibit dormancy to the same degree and in the same way. And I think there is wide range of conditions that can acutally be called dormancy, and it doesn't have to be that the plant shuts down completely, although it could mean this. What I do know is that all plants (and animals also) have a range of conditions they can tolerate and still live and grow. When they encounter conditions that go beyond their abilities to tolerate, they respond by slowing or shutting down the most non-essential functions first in order to survive in the long run. I think of this shutting down process as 'dormancy', but I wouldn't want to try and apply the broad concept of 'dormancy' to every hosta under all summer conditions, nor do I think that hostas have an on-off switich that they are either full-out growing or fully shut down, but I'd sure to know if I'm wrong about that. I would think there is a lot of variation in how and to what degree various hosta species and cultivars go dormant -- which is evident by the timing of their fall dormancy that also shows variability among types.

Do I think the prolonged HIGH heat, (90 to 100+ degrees), low humidity, wind, and no rain for 8 weeks in my area has caused my hostas to slow down in some way? Yes, I do, but exactly how each type has responded I don't know. And, I don't think it necessarily shows now because there is a lot going on inside the plant tissue that we don't see. In fact, the effects that any degree of 'dormancy' is going to have won't show up till next year - either smaller or less eye development, less leafing, or less flowering, or even bacterial crown rot in cases where a plant did shut down all cellular processes, which is maybe the classic meaning of dormant. I know that many of my mature hostas are flowering less vigorously this year, and I think this is due to the extremely prolonged and high heat we had for 2 months last summer - regardless of how much water is available, certain environmental conditions are bound to exceed a hostas ability to take in enough water (those thick, unbranched roots) and to transport it through its tissues effectively. Under such stress, the plant responds by lowering its growth demands in some way, which is at least a partial dormancy to me. While I don't know the exact physiology of what's going on with each type of hosta, given that hostas are native (evolved) to cool and moist areas of Japan, China, and Korea, the hot and dry conditions my valiant hostas have endured the past 2-3 years has caused them to adapt while growing -- likely through some type of dormancy if you want to call it that -- in order to survive at all.

Looking forward to hearing from the experts who likely know the specific physiology of a sieboldiana vs. a tardiana vs. a fortunei etc. under stress conditions.

Here's wishing rain and cooler temps to all those that need it.

Linda

[John Polka]

Thanks for your input Linda... like you said I'm sure our plantaginea aren't hurting as bad as our sieboldiana...
John

[Mark Raw]

I have never realised they had a summer dormancy but it does expelain what I class as the sulking period. They grow their leaves then stop, usually during this point they flower (some of mine are beggining to enter this stage now) and then after flowering they seem to get a new spurt of growth. I somrtimes find these leaves (second lot) can be slightly different shaped, especially on some August moon a particular example (almost banana shaped).
I also class sulking as when they emerge and dont grow very much that year then the next seem to show a major difference. It was a term I picked up from John Deardon at one of the Holker shows

[Chris_W]

Can you explain this one to me a little more? Do you mean how plants appear to stop growing in the summer, or are you talking about plants actually losing their leaves in summer and growing back later?

[guardbear]

Hi Chris
I can only answer for myself, but I understand the concept to mean that the plant does actually shut down, i.e., it goes to sleep and stops or severaly slows down cellular processes. So in that sense it is the same as fall dormancy, and I could imagine that under very, very prolonged stress of heat, no water, or whatever, the plant would stop transporting water and leaves would eventually die -- again, just like fall dormancy. But, I have not heard of summer dormancy being so intense or persistent that it mimics fall dormancy completely. I don't understand it to mean that the plant loses all of its leaves in the summer through dormancy and then replaces those leaves in that same year. As far as being able to 'see' the plant stop growing, again I can only answer for myself and I can't tell a lot of difference in my plants from mid-June through the rest of the summer in terms of size or added leaves (except that they bloom of course), but I don't attibute this to 'not growing' -- just that they are just doing other things below ground that I don't see. I understand summer dormancy to mean that the plant looks the same above ground -- so long as it doesn't stay dormant for so long that aboveground tissue is damaged. So for me, we're talking about real summer, that is past ~June 20. I think the concept of summer dormancy relates to heat mostly and that some hostas simply go dormant, but as temps cool, they start up their cellular processes once again, until temps lower and they enter fall dormancy.

I think the more simple question being asked is whether this is a universal thing that happens to all hostas in the summer. And, I don't understand the concept to mean that.

Hope this helps a little, at least for how I understand the idea.

regards,
Linda

[Mark Raw]

The best way I can explain it is;the plant puts out its first set of leaves then suddenly leps and before you know it they stop and after a while folwer (ig they are going to) then there is a sudden outburst of more leaves usally smaller ant narrower thant he first set. then before you know it they are going down again. they dont loose their first set of leaves they just sit there til the next surge of leaves.

[thy]

Mark...lack of water,.... in your place the last years ??????????????????

Linda, think you have a general point in

the effects that any degree of 'dormancy' is going to have won't show up till next year

and I think we often forget the year before... or just the spring before the late summer, droughts will show some time

[morgansrgr8]

I had a couple hosta completely die back during the summer to show up again the next spring. I thought it had died. I wouldnt want to put it to a test tho.