Help - yellow tomato leaves!

[Chrissie]

Hi folks,

I'm growing several types of outdoor tomato on my kitchen windowsill with a foil reflector behind - they're coming on well (about 3 inches tall in 3 inch pots) but I've just noticed the lower leaves are starting to turn yellow.

I know this is a sign of stress but I'm not sure what I'm doing wrong! Too hot? Too cold? Too dry? Too wet?

Thanks for any advice...

[Chrissie]

[Tee Gee]

I've just noticed the lower leaves

Do you mean the seed leaves or the first pair of 'real' leaves?

[Robert_Brenchley]

If it's the seed leaves, they don't last long, and die as the plant grows.

[Chrissie]

Thanks for replies - the seed leaves are the worst but the "real" leaves are definitely looking pale and sickly.  It seemed to happen very suddenly. 

They got a bit hot on the windowsill over the weekend so I gave them a fair amount of water. Could that be the problem? Perhaps I should move them somewhere cooler. Oh for a proper greenhouse...

[Tee Gee]

I gave them a fair amount of water.

How much is fair? :)

Are they saturated?

If they are then this could be the reason.

Ease off on the water! try feeling the weight of the pot now when it is wet then when you think it might need more water check the weight again you should notice an appreciable difference in weight if it has dried out.

[Chrissie]

Yes it probably was a bit too much Tee Gee, thanks  :-[. The poor things looked so thirsty.

You learn the hard way...

[cleo]

try feeling the weight of the pot

Words of wisdom indeed-it doesn`t take long to get a `feel` for it and is a wonderful indicator

[Chrissie]

Will do, thanks.

[MrsKP]

how about a magnesium deficiency ?   ???