Bulb Log 46– 12/11/2014

[johnstephen29]

Yes it's been really dull and wet down here, what's keeping me going is the thought that in less than a month the days will start to get longer, though the weather is usually at its worse then

[johnstephen29]

Hi Ian can I first say how much I am enjoying your bulb logs, they are really informative. I have been looking at the last few months logs again & I really like the new staging you have in the frit house, do you mind if I ask you where you got it from, I could do with some staging like that myself or something similar. Thanks John

[Maggi Young]

Hi John, the staging is from Two Wests and Elliott www.twowests.co.uk/‎   several other forumists and friends  have bought their staging and frames and spoke well of them so we went with that firm too- excellent service and good quality staging - they'll make to  fit if you've got an odd space to fill, too.  See some about it  here :  http://www.srgc.org.uk/logs/logdir/2013Jul311375281392BULB_LOG_3113.pdf

[johnstephen29]

Thanks for the link Maggi I'll take a look.

[johnstephen29]

Hi Maggi I hope you don't mind me asking another question?, with these soil warming cables would you still have to put up bubble wrap for winter protection?

[Maggi Young]

We never put up bubble wrap in winter, John. The soil warming cables should protect the actual bulbs if there is a really bad freeze and any which have above-ground growth in winter are amazingly good at coping with a freeze.  Nearest we have ever come to any sort of overhead protection has been to use a covering of horticultural fleece over them when it's gone really low and threatened to stay there- but we haven't even done that in most cases - which may, of course, be why we've lost some stuff over the years. But we try to grow them as tough  as we can!  Amazing how much cold the leaves and flowers of the winter flowering bulbs can take in winter - they may flatten for a while  but pick up again.

I'll ask Ian to speak about this in a log soon.

[johnstephen29]

Thanks Maggi I was just wondering if I could have the same kind of set up in my greenhouse, i don't only have bulbs in there as you saw in the photos I posted last month so I wonder if it would work.

[Maggi Young]

Since we don't have any heat  in the glasshouse, apart from the soil-warming cables, I'm not sure how they would work with your need to have the glasshouse kept completely frost free for your range of plants, John. Someone here  will  know better than us about that - there are plenty here who do keep a house frost free I'm sure. 

[brianw]

Apologies for putting this in the Bulb Log but it follows on.
To cut the costs in the heated end on my greenhouse I clad the outside with plastic sheet, held to it by bamboo canes wired to the aluminium between the sheets. Reduces to some extent the heat losses from the aluminium extrusions and reduces the airflow over the glass.
All looks quite pleasantly rustic.

[Maggi Young]

That sounds interesting, Brian - have you got a photo  to let us see? I can't quite imagine hot  it works. Is it easy with the bamboo  to keep the wind from ripping it off?

[brianw]

This is 2 recycled greenhouses joined end to end. a 12'x8' + 8'x8', from that good old English/Scottish BaCO company, about 40 years old. Needed some corrosion cleaning off and a few new bolts and glass but otherwise fine. Only the 8'x8' end is heated. The internal partition is twinwall polycarbonate too.
The end and side you can see is just Wickes roofing grade polycarbonate clamped against the frame by twisting wires passed through a drilled hole in the extrusion at the appropriate point between the sheets. Thought of all sorts of other ways but canes seemed the obvious and I had them. This is the north and west sides. The roof will be covered in 3mm acrylic sheet, just laid on the top and hung from the ridge, shaped round the roof vents, and fixed similarly with canes to the south side. I had these on a previous greenhouse and had fortunately acquired them from a company that had used them as office partitions; free. The intention is to remove them in summer, although really only the south faces need shading much. The north long side of the greenhouse faces (10' away) a high evergreen hedge with a topped copper beech in it, hence the leaves. Will probably install some frames down that side.

[Maggi Young]

This is a post made by Paul Cumbleton in  a South African Bulbs thread ( http://www.srgc.net/forum/index.php?topic=12660.msg328112#msg328112)

Returning to the subject of LED & other forms of lighting, I hope it will be useful to point out a large misunderstanding that has persisted for a long time. This is the belief that alpines and other plants grow more compactly in the wild than they often do in cultivation due to being exposed to higher levels of UV radiation. This is actually not true. In his bulb log last November http://www.srgc.org.uk/logs/logdir/2014Nov121415787177BULB_LOG_4614.pdf Ian showed the new LED system that Gothenburg is trialling and said that they were "high in UV" for healthy growth. If you check the spectrum of the lamps used on the company's website, you will see that actually these lamps cover the range of 400nm to 735nm  - which encompasses the photosynthetic spectrum but not the UV. In fact these lamps don't give out any UV light at all.

Science does not yet fully understand all the ins and outs of the specific effects of various wavelengths of light on growth, but experiments on alpines have shown that levels of UV light do not affect the stature of the plants. In fact, like most things, UV can damage plant tissue just as it can damage your skin if you stay out in the sun too long. Experiments show that most plants actually reflect the majority of UV light that falls on them in order to protect themselves from damage. And the experiments also show that of all groups tested, Alpines reflect the most UV (more than 90%).

As well as experiments, observations in the wild also point to the fallacy of the idea that it is the UV keeping plants compact. For example, many arctic and sub Antarctic plants inhabit misty coastal ranges where they receive very little UV and yet they are extremely stunted and dwarfed. Also, if UV intensity had a significant effect, you would expect to see latitudinal gradients in the stature of alpine plants, but this does not occur.

So what does keep alpines dwarf and compact? While the full story may not yet be in, the evidence all points to LOW TEMPERATURE as the key factor. Our alpines in cultivation grow out of character largely because we cannot keep them cool enough. It is also known that the overall intensity of light (of all the useful wavelengths, but not UV) has a part to play at least for some species.

For those who would like to know the references and read more about this, the best place to start is the discussion about all this on pages 114 to 119 of the book "Alpine Plant Life - Functional Plant Ecology of High Mountain Ecosystems" (second edition) by Christian Korner ISBN 3-540-00347-0

Paul

It all begs the question - what then are Gothenburg using the lights for, if there is no effect  re UV, as supposed ? 

Ian's impression was that it was the higher levels of all  the spectrum of light, including UV,  that was the point of these  lights.  Either he got the wrong end of the stick as regards the description he was given, or he and the GBG folks are all labouring under a misapprehension!

Hi Maggi,
The lights at Gothenburg would still be useful for increasing the day length (especially in their northerly latitude) and the overall light intensity the plants receive and these should lead to improved growth. The operating costs should also be cheaper than traditional grow lights. I would imagine that these are the reasons they are trialling them. Though the 'myth' that UV improves compactness is so ingrained that it would not be a surprise if they were also under that misapprehension.

Paul