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I have several plants in pots in an undercover bit outside. Would they still need watering this time of year? There are various climbing plants like clematis, wisteria, passion-flower and honeysuckle, flowering bushes, fruit trees (which are now cover with that fleecy stuff), garlic & avocados. My hubby thinks they dont need it but I reckon they do as they would at least have the rain if they were outside.

I would water them, but sparingly, and that dependant on how cold it is (the colder it is the less water I'd give them).

Ok - this may be a really DUMB question, but I will ask it anyway...

When it is really cold over there, is it of any use/benefit to water your potted plants with warm water? Do folks do that, or would it just freeze anyway with the outside climate and end up making things worse?

...Just wondering.

Yes, they'll still need watering except during a prolonged freeze, but less often than normal. I'm watering in my tunnel about once a week, and to tell when I need to I just use a trowel to dig down about an inch and see if the soil there is still moist. It's better to water often enough to avoid pan forming in the top layer.

Warm water - I can't see the advantage here as it would cool off in a matter of minutes. In fact, I'd have thought temperature fluctations round the roots were something to be avoided, particularly when it's very cold.

I wouldn't water with warm water while there's the chance of freezing - warm water freezes quicker than cold.

If there's no chance of freezing in the covered bit, try spraying the plants instead. Get some fetilizer in te spray and you're giving them a bit of a boost at the same time.

My wife also maintains that warm water freezes quicker than cold. Why is this? It's counter-intuitive.

I asked my husband this last night, and he too says it's true. I've just googled it, and it can happen and is called the Mpemba Effect. http://physicsweb.org/articles/world/19/4/4

I agree it is, and used to dismiss it as an old wives tale. But this came up on here a while ago. I did a bit of Googling, which produced enough results to convince me there was some sound physics behind it.

Damned if I can remember what the theory is now (something to do with the behavior of molecules, I think), or the thread it came up in. But I'm pretty sure I posted a link that explained it. Perhaps do a bit of a search through the forum. I suspect it was well over a year ago.

If you find it, let us know; I'd be interested to revisit it.

Found it.

These are the links I posted

http://www.desy.de/user/projects/Physic ... water.html
http://www.lsbu.ac.uk/water/explan4.html#mpemba

'Tis indeed about the Mpemba effect, but it only happens in certain circumstances.

Ah. Hydrogen bonding. *nods sagely and hopes he sounds like he knows what he's on about*

ok...this is how it was explained to me at the age of 11...

When something is solid, its molecules are standing still. When it is a liquid, they are walking about, when it is a gas, they are flying.

When water is cold, the molecules are walking slowly, becaus ethey have big coats on. When the water is hot, they are running about with nothing on. Therefore, when you freeze hot water, they don#t have to take their coats off, so they can stand still quicker.

It makes more sense in my head...

That is a great way of explaning it fee.fairy. Will have to remember that for the next time someone asks me. Thanks

But do remember that it is only under certian conditions that warmer water will freeze faster than colder. It would seem that this isn't the normal case. I guess it all depends upon which molecules remembered to take a coat with them

Ah, good point Muddy. One i forgot to ask about at the age of 11...

Apparently, that's how it works when you make ice cubes in the freezer - the ice comes out clearer as well.