Purple tomato leaves

[cestrian]

Hi - My toms are going great guns in the greenhouse. They are in ring culture pots and they are about 2-3 ft high, but I have noticed that some of the bottom leaves have started going purple. I read somewhere that it might be potassium defficiency!! but I feed them once a week with doff tom feed at the dilution on the bottle. It is the leftovers from last year though. Can tomato feed go off or become less effective over time? The other thing I was doing was adding a spoon of epsom salts to each watering can to give them a magnesium boost. I've stopped using this now in case the extra magnesium was stopping the potash from being absorbed.

Has anyone else come across this before?

[cestrian]

[Tee Gee]

Based on what you say you may have overdone the Epsom salts, particularly as you are feeding with a high potash feed at the same time, or they might be in a draught!

This link might help;

http://www.thegardenersalmanac.co.uk/Data/Tomato-Leaf%20problems/Tomato%20-%20Leaf%20Problems.htm

[pumkinlover]

I seem to think that I  heard or read recently that it can be due to cold as the plant cannot metabolise the potassium.

[davyw1]

Its not uncommon and the plant will grow out of it as it matures. it can be caused by cooler growing conditions and stress cuased by not being able to absorb nutrients. Another factor is over watering.
If these leaves are below the first truss nothing stopping you from removing them but no more than two at a time as this can also cause stress.

[GREGME]

I've had this on most of my toms this year-but they are surviving and some have pulled out of this I am putting it down to below par temps affecting potassium absorption which should be ok given they have all been comfrey fed. Had first blight text warning yesterday so with this aswell not expecting a good outdoor tomato year.

[lottie lou]

Thought you shouldn't feed tomatoes until the first truss forms.  Perhaps I am wrong in thinking that means the fruit rather than the flowers.  I then use any comfrey tea (usually last years) diluted on them.  Outdoor toms doing pants and hardly grown at all since planting out, would it be okay to lift them and pot them up even though the first flowers have formed?

[cestrian]

I cut back on the watering this week as it's been cooler since the weekend and I've completely cut out the epsom salts as I read magnesium deficiency usually comes towards the end of the season. I've also been removing some of the purple lower leaves anyway. We'll see how it goes. The plants look really healthy otherwise. Trusses set already!

Btw Lou my outdoor toms 'outdoor girl' are doing better than those in the green house. They were the first trusses to set. I'm always careful about which variety I grow outside, some varieties do better than others.