Mine's gone all floppy

My Eupatorium has gone all floppy - any ideas why? When I saw it first a few days ago, I thought it was short of water. But it recovered. Then I noticed it again today, and it is certainly not short of water. It has been raining hard all week, the ground is sodden, and it is in the wettest part of the garden, as Eupatorium likes moisture.

I haven't been watching it that carefully, but it is already much better an hour after the photo was taken, as it has moved into the shade. And I am sure it is always fully recovered in the evenings. I suspect it that it is the effect of the sun, which raises the temperature of the leaves leading to a much higher rate of moisture loss, and that as soon as the temperature of the leaves falls such as when it is overcast or in the shade, the stems can cope again.

I don't remember noticing it last year, or I may have seen it and watered it and then forgotten about it. Otherwise the plant is wonderfully healthy. But I have noticed, in previous years, that some other plants such as Echinacea have gone floppy at a time when I didn't think they were short of water.

Has anyone else experienced this with any plant?

 

Yes. Hydrangeas (yes,I know,again, sorry I have so many of them that they are rather prominent in my gardening experience) easily flop if it is hot, even if they are well watered. They perk up again as it cools down. I think it is intended as a way to reduce eveporation, it certainly looks dismal. Stressed or freshly planted specimen are more vulnerable, but that does not seem the case of your eupatorium. Any chancethat something may have marginally damaged the roots?

 

Hi Ivory - hot is not a problem we will experience in the UK this year ! :D

 

Peter you have hit the nail on the head with your second paragraph,transpiration is not fast enough in full sun on a hot day and the wind exacerbates the problem,I get it a lot with the brugs which is why I recommend they be grown in less than full sun,I use a shade sail and put the ones most vulnerable under that.
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Transpiration.html

 

Hi Ivory - hot is not a problem we will experience in the UK this year !
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Harry

Yes, not in Germany either, but "hot" is very realative for plants, In proportion they lose a lot more water than we do when in the sun, and if it is windy as well so much the worse.

 

Thanks Ivory. I hadn't realised that Hydrangeas do this as well. I have one growing close to the said Eupatoreum. I will watch it more closely in future.

Walnut, I saw your sail awning - I thought you were just trying to be trendy! - but a similar problem. That's an interesting page. I am impressed with the figure that sweetcorn plants transpire the equivalent of 15 inches of water. That's in USA of course so it would be a bit less over here, but that requires 15 inches of rain over and above any evaporation from the ground, and water drained to rivers etc.

As expected my plants were perfectly healthy and upright last night and now again this morning in bright sunshine. Its something that I haven't been aware of before. As you learn more about gardening, you look past the obvious - is the plant dead or alive, in flower or not - and start seeing the more subtle aspects.

 

Hi Ivory - you know, if you hit the in someone's post, you get their post all neatly bundled up in a box like yours is here.

 

Thanks, I know... sometimes I just forget! I am terribly good at complicating easy things :(

 

Walnut is spot on with this one. I have a number of plants and shrubs doing the same thing. I noticed it more this year, but then last year was such a cloudy year, and 2006 you expected it with all that heat and no rain.

Amazing how fast they pick up though. From looking like they are on their way out to being upright and vigoruous again.

 

Is this the same as the plant I know as Hemp Agrimony? I collected some seeds last year from the plants growing by a stream in the park, attractive fluffy pink flowers?

 

Virtually the same Liz. According to my book:- Hemp Agrimony is Eupatorium cannabinum the British native wild flower, which I think has smaller flower heads and the book says grows to about 5 feet. Mine is Eupatorium purpureum (Joe Pye Weed from the USA). Which has huge flower heads and the book says grows to 7 feet, but mine are 5 to 6. If it was a council park yours could be either species, they are both offered as garden plants.

I think it is a really good plant, it offers height, has big flower heads, looks attractive and flowers for a long period.

I have been watching mine closely, and it fully recovers every evening. I think the key perhaps is uninterrupted sun. It didn't hang its head today even though it has been just as hot as when the picture was taken, but there was a short overcast spell midday.