Topic: overwintering tomatoes in the ground to prove a point.

[kypfer]

Just a thought ... if my schoolboy physics still holds me in good stead ... but I'm not sure that painting these "wall of water" devices black will be of significant benefit. Agreed that a black surface more readily absorbs heat than a white surface, but it also acts as a more efficient radiator, so any extra heat collected in the hours of daylight will be more quickly lost once it gets dark ... or have I missed something  :-\

The same probably holds true for specifically black mulches and/or adding soot to soil to darken it. I'm not saying that a mulch is is not a good thing, just that a black mulch is possibly not more beneficial than any other colour. It'd be interesting, once the nights get colder and if one had the space and the resources, to lay out a black sheet, a green sheet and maybe a clear sheet on the ground next to each other and monitor the soil temperature on an hourly basis under each over a period of days.

One might even suggest that a light-coloured mulch would reflect more light onto the plants ... all interesting stuff  ;)

[galina]

I did not bother to paint them black.  The first night they were filled with warm water but after that I found they warmed up quite well during the day.  In general the coldest nights are on sunny days.  

No need to paint them black, by the way.  I fill them with diluted comfrey liquid fertiliser, any other brown liquid fertiliser will do.  I have measured a few degrees of difference from just plain water and they feel warmer.  At a later time it is useful  to have the liquid to hand.

Why is it that dark bottles give off their heat quicker?  I have never heard of this.

[kypfer]

Why is it that dark bottles give off their heat quicker?  I have never heard of this.

It's basic physics, the same reason that car radiators are painted black (to lose heat) and solar panels are black (to absorb heat) - you can try it in the kitchen with a couple of different coloured mugs and some hot water - assuming similarly shaped mugs of similar material and equal quantities of water, the contents of the darker mug will cool down quicker than the water in the light coloured one  8)

[Jeannine]

If anyone wants any I can ship over for you, they  also are on UK e bay by the way XX Jeannine

[Digeroo]

I must be doing something wrong.  What exactly did you put in the search to get them to come up on UK ebay.  The only thing I can find are repair kits from US.

[Jeannine]

I'll find then for you XX Jeannine

too may to get alink

Go to UK ebay

Make sure you have worldwide tapped at the side, if you just have UK they won't come up.


Spelled                 Walls O Water             in all categories first.

They cane up red, green, packas of3 and large packs XX Jeannine

[Digeroo]

   Since the real thing come from US the postage is very high.  But I actually quite like the challenge of doing it with a ring of plastic bottles.  If I use milk bottles I can put a ring round through the handles to prevent them falling over.  Though coke bottles are taller.

[Jeannine]

Thay are quite tall, taller than bottles.

[galina]

Why is it that dark bottles give off their heat quicker?  I have never heard of this.

It's basic physics, the same reason that car radiators are painted black (to lose heat) and solar panels are black (to absorb heat) - you can try it in the kitchen with a couple of different coloured mugs and some hot water - assuming similarly shaped mugs of similar material and equal quantities of water, the contents of the darker mug will cool down quicker than the water in the light coloured one  8)

Thank you.  Must have been ill, during that particular physics lesson.  So, dark bottles are good because they absorb more heat, but we need a cover (or use inside greenhouse) to keep given off heat in better.  Live and learn :)

[kypfer]

dark bottles are good because they absorb more heat, but we need a cover

... to keep in heat overnight, but removed during the day to "re-charge" the heat.

 ... good thinking  8) sounds like a sales opportunity ... Dragon's Den anyone?

[Digeroo]

So does that mean that you have to tend to them everyday to move the protection.  And surely some days will not be warm enough during the daytime.

[kypfer]

So does that mean that you have to tend to them everyday to move the protection.  And surely some days will not be warm enough during the daytime

Let's not get too bogged down in the detail here  ;)

The basic concept is good, the water device absorbs heat during the day and then releases it again at night ... it also acts as a windshield and/or cloche so can only be a "good thing" ... it's just that if one was to fit a cover of some sort each evening and remove it again the following day, it'd probably be even better  8)

If the water device is dark coloured, so it absorbs more heat during the day, it will have more heat to release overnight, but is likely to do so quicker, as it is a more efficient radiator, being dark, so the nett result will likely be very similar to an uncoloured device. One also needs to consider the plant's need for light. Obviously a dark-coloured device will leave the plant more shaded, so more likely to grow "leggy".

I think this is another occaision where most simple is best ... a ring of clear plastic containers filled with clear water is likely to give the best compromise, a clear lid for the whole device is probably worth considering, an overnight insulating cover would be a bonus for those with the facility for removing it on a daily basis.

[tricia]

I think this is another occaision where most simple is best ... a ring of clear plastic containers filled with clear water is likely to give the best compromise, a clear lid for the whole device is probably worth considering, an overnight insulating cover would be a bonus for those with the facility for removing it on a daily basis

Adding anti-freeze to the water too?

Tricia

[Jeannine]

Been reading a few things online..have found some folks are sayingthat the red ones are slowing growth rather than speeding it up.

I used these for my squash plants originally, I planted on plastic much that had been down a week or two then the water walls, I sometimes put a small tomato cage round the plant then the water wall as I was convinced they wouldn't fall over but they never did.

I contacted Veseys by e mail but they will not ship to the UK. I will check mine for weight, they come in packets of three.

XX Jeannine

[nilly71]

A bit of info for making your own http://www.ediblecommunities.com/frontrange/component/option,com_wordpress/Itemid,300107/p,1300/

If I use milk bottles I can put a ring round through the handles to prevent them falling over.  Though coke bottles are taller.

Milk bottles on their side would be better. Lay one course down, then a piece of wood or canes could be put through the handles and driven into the ground, then slot the rest of the bottles over until you reach the hight you need, and tied together when you get to the top.

Neil

[Digeroo]

Brilliant.  I shall start collecting the milk bottles right now.  I shall log the 1st Feb into my mopho to bleep me.  It is a very auspicious sowing day being two days before the new moon and two days after the Garden Organic Potato day.   

Planting out day will be the 1st April which is perfect because it is a very foolish scheme. 

[kypfer]

Adding anti-freeze to the water too?

Not sure about this ... or bleach to prevent the algae ... both points worthy of consideration, but I have reservations about potential contamination issues in the event of a rupture of the container, or simply forgetting about what's in the water and tipping it onto the ground/crop when taking the device out of use  :-\

A point to remember, if using such a device in an area where the water is likely to freeze, is that water expands when it turns into ice, so don't screw the lid on tightly, if at all, else the plastic is likely to split.

[Digeroo]

I am also not sure about the antifreeze it is the latent heat of fusion that comes into play and rather surprisingly releases heat when the water freezes.    Also water has a maximum density at 4C so the water at the bottom stays warmer for longer hence the need for taller containers rather than stacks of smaller ones.  It is the particular properties of water that are required.  There is no need to prevent the freezing there is no particular benefit from stopping it, it is beneficial.

It is the higher density of water at 4c which ensures that ice rises to the top and the fish etc have somewhere to live underneath at a barmy 4C. 

Plastic milk bottles expand slightly, coke bottles are designed for high pressure, cheaper alternatives do split.

[plainleaf]

i find the debate about how they work a bit funny. I have use walls o water down to min temperature  of 15 f  on 3 nights and 5 nights at 17 f.  during several tough winters.

[Digeroo]

That is quite impressive.   I have got so used to the weather forecasts I had to have a conversion we are talking about -8 to -9 C.   I had thought we were taling about the odd degree or two of frost.   I presume by this time the whole thing is totally frozen stiff so must rely more on the insulation properties.

If I put out tomatoes in April I would not expect such low temperature here.  We had them in February last year but that was something of an exception. 

For courgettes I also have a couple of large flint pebbles which take in heat.  I also bang  in some metal bars which I hope take the extra daytime heat down to the roots.