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Water for protecting glasshouses

Following Bob Flowerdew's comments on his experiments on storing water in greenhouses to regulate temperatures on GQT, this is the second winter I have emptied a couple of full size plastic bins of compost and placed them in my two greenhouses, and filled them with water and replaced the lids. It seemed to work last winter, I lost hardly any tender plants and not using bubble plastic I could ventilate them properly when needed. But we barely had a winter down here in reality. What will really test them is this Arctic winter we keep hearing is heading our way. The most finicky thing still in one greenhouse is my much coveted Uncarina, a cold and damp hater from Madagascar, and though my wife hates it because it looks tatty and is nothing more then a large twig in winter, once the leaves go it will have to come in and be forgotten about until next May, when it will resurrect into a handsome plant again. Let's see how the rest get on, Mr Flowerdew says this does work for him, and his winters are proper Norfolk ones, not these soggy non-starter efforts we have here in Wales.

Comments (4)

  1. Grower

    Winifred Field

    What was the idea, didn't hear the programme myself. Can you explain further?

  2. Grower

    Rob Johnson, Green & Furry pet and garden care

    Hi Winifred,
    So the theory goes...... Water in volume absorbes heat during the day. It is then released during the night as the air around it cools. When water starts to freeze even more heat is then released and so protects your plants. We have already had cold temperatures this Autumn and the fuchsias are still in flower in the glasshouses even though they have been clobbered outside and the plants look very happy as I can open up during the day which I couldn't with bubble plastic to my satisfaction.So is it working? I'm not sure yet as it is quite mild and sheltered in our garden so let's just see what the winter brings.
    I suppose thinking about it you see it all the time with places near a body of water with mild maritime climates. I know at Ambleside, with Windermere lake stretching South west from right next to it you see fantastic tree ferns and tender plant in the gardens, amongst what is otherwise a harsh and unforgiving climate, balieve me, I was born and brought up there and the weather is no fun sometimes as pretty as the scenery is. I saw a documentary on I think the Andes where the farmers were growing crops along a network of water filled ditches in order to protect them from frosts,so that is the theory I think.
    The GQT where this was mentioned was aired last year, Bob Flowerdew said he was just experimenting with the idea, so I thought I would try it myself, especially if it meant dumping the dirty paraffin heaters, the fumes of which seemed to cause more damage then the cold, and the bubble plastic which encouraged fungal desaeses. I will see how it goes, that's all I can say at the moment, nothing ventured, nothing gained

  3. Grower

    Winifred Field

    We live and learn! As you say that does make sense. My greenhouse is very old so there is not room for any sizable container stand. I bubble wrap it and put fleece over plants when the forecast is for extra low temps. and as you say the last couple of winters have been exceptionally mild. I have also left filled drinks bottles standing among the plants in the hope they absorb heat during the day and return it at night but again I could be wasting my time? Well here's hoping it will be a short winter with just a few frosts to do the bugs in!

  4. Grower

    Rob Johnson, Green & Furry pet and garden care

    I think leaving bottles and cans of water between plants is not a waist of time, even the odd watering can of water all seems to work quite well. In the past, I left water in containers inside the greenhouses so it would heat up sufficiently so as not to give plants a cold shock in winter, I noticed even then the plants looked better. Bob Flowerdew even recommends lining old plastic pop bottles full of water around the greenhouse to help. I feel, if you can, a larger body of water, eg a plastic bin with the lid tightly on provides a more stable situation. I have some pretty odd plants, like little autumn flowering hyacinthoides, a bluebell like bulb from Morrocco. They do not like any frost at all. So far this is their 2nd winter with this method and they like things much better this way then with the bubble plastic. It all looks quite promising, but I have since read the Victorians often used this very same method. Nothing new under the sun!

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