Pot heating.

[metalhammer]

There was an interesting article on Gardeners' Question Time this afternoon about the effect of different pot materials on the heating of the compost.They had 7 different pots,all of which I can't remember,but plain terracotta was the coolest at 25c,glazed terracotta was about 30c.Thick black plastic was the hottest at 40c(no surprise there),but very thin black plastic was surprisingly cool.Metal was 37c.So if you want to warm the soil,obviously plain black plastic(thick pot)is the best & terracotta if you want to keep the roots cool.

As they said,terracotta is best in hot climates,where as black plastic would be best for cooler areas.




metalhammer.

[kata]

Thankyou MH

Most useful imformation.

[Dave Brown]

I find any black pot is warm. Terracotta colour plastic pots are also quite warm. Terracotta clay pots are cooler as they transpire moisture and the evaporation from the surface lowers the temps.

[medjool]

Hi gents
Wouldnt it be a good idea to have Black plastic pots with a liquid filled cavity of some liquid that freezes at very low temperatures,absorbs heat in the day and radiates at night.

[Dave in Warrington]

Thanks for posting this Metalhammer and It's certainly got me thinking

Especially with my Blue glazed terracotta pots, I can see I'll have to get the temperature sensor in these pots to see how they compare in then sun

[metalhammer]

I have no doubt if you go to the Gardeners' Question Time website on Radio 4 you'll be able to get the full results.


The thin black plastic pot was about 7 or 8c lower than the thick black pot.



edit,as computers & websites are like talking in Cantonese to me,I have absolutely no idea how to find the info on the pot test on the website.What the hell is a podcast?,what is an iplayer? - have I moved unknowingly to the 22nd century whilst a sleep?.




metalhammer.

[weve]

Medjool

Think those "water-walled" pots of yours would be an excellent idea for evening out the day/night temperatures, but do they commonly sell such things?

I have two plastic square containers (in a ghastly pale yellow colour) where the 1" thick walls and base can be filled with water. These were given to me, but I never have seen anything similar for sale.

(Trouble with these tho' is they have no drainage holes. perhaps they were meant to hold another container)

[sooty]

Newbie here -
Is a cool pot better than a hot pot - in particular do aroids/bananas prefer hot or cool roots
I'm not sure whether this is good practice but I line my terracota pots with plack plastic to avoid excessive water loss, whilst maintining the decorative element of the pot. I don't line the bottom, just the sides.
How does that option fit into the scale of things and is it likely to lead to problems - rot etc?

[kata]

have I moved unknowingly to the 22nd century whilst a sleep?.

http://www.bbc.co.uk/iplayer/

Thanks for reminder MH..I need to catch up on Holby City, missed it last time due to moving.

Podcasting

http://www.podcasting-tools.com/

All pretty oldish technology now really.

[Dave Brown]

Hi Sooty, and welcome

Aroids and bananas prefer warm soil, as most are from tropical countries. Cold soil will halt Aroid growth in most cases.

By stopping evaporation from your terracotta pots they will be warmer when dry. I used to put wallpaper paste around the inside to seal them or watering can become a twice daily chore in summer.

[sooty]

Thanks Dave,
On that basis, what's the best container to use for bananas/aroids. Are the lined terracotta pots too cold realistically?
I've currently got 3 7/8ft basjoo's in v.large plastic terracotta-coloured containers. They seem to be happy with 4/5 offshoots each and growing a new leaf per week.
I picked up a Maurellii and Alocasia Macrorrhizos from Vale Exotics a month ago and they don't seem to be going as quickly as anticipated. They're in my lined clay pots, watered with warm water-butt water and miracle gro twice a week.

[AirKewl]

Medjool



I have two plastic square containers (in a ghastly pale yellow colour) where the 1" thick walls and base can be filled with water. These were given to me, but I never have seen anything similar for sale.

(Trouble with these tho' is they have no drainage holes. perhaps they were meant to hold another container)

'Weve', you need liners for those? - Think of an old oil lamp with a wick, same difference, the liner has a felt bottom & felt wick, which sucks up water from the resevoir (container) - I'll post a link to the manufacturer if you're interested?

[mowerman]

I've always preferred unglazed clay pots as they can be virtually impossible to overwater. In my early days in exotics I lost a few Agaves in plastic pots due to the container retaining too much water during the winter despite a well drained soil.

[Rich]

So in theory most palms will grow quicker in a plastic terracotta coloured pot than they would in a real terracotta pot of the same size?

[Dave Brown]

I'm using the terms Clay and plastic, as terracotta, which is the clay used, is also the colour of some plastic pots.

I agree that Arid plants are better off in clay pots rather than plastic as mositure evaporates through the pot. However, they really prefer a loam based compost rather than peat or other organic material, regardless of pot. Naturally you don't get peat or bark soil in a dessert Most Arids are supplied by the nurseries in peat which is fine in summer but a real problem in winter.

The problem is, plants that need lots of water in the warmer months but much less so in winter. These include Alocasia, Colocasia, Ensete, and many Musa. I have come to the conclusion these are better depotted and downsized into much smaller pots in October/November. The moisture retentive compost they love in summer is replaced with a much freer draining mix....but they migh benefit from clay all year round if you can water enough in summer.

Heat can be a problem in some areas, and they seem to use black plastic pots even in hot countries. I think this is where the pot planting is benificial as the pot is kept cooler.

For warmth and airiation here maybe the best product would be a black clay