Purple leaves on tomato plants

[blackcatlois]

I've just noticed that two of my tomato plants have purplish leaves at the bottom - the rest of them in the same greenhouse are fine - could they possibly have a virus? It never gets below about 8 degrees at night as I use my greenhouse heater when cold weather is likely. Thanks

[zazen999]

Some say they are too cold

some say it is a sign of hardening off

I rejoice when my toms get this as it means they are coping with the cold.

[teakdesk]

My toms are kept in a heated glass frame inside the greenhouse.
Minimum temp in centre of the frame is 13 degC except for a couple of very cold nights when it dropped to 10.5 degC.

I also had one, yes just one, tomato show purple on the seed leaves as in the photo. There is a hint of purple in the stems but nothing to worry about. I do associate purple with cold and this plant was close to the glass in the coldest part of the frame so may have got colder than others in there.

The plant is still growing well a few week's after the purple appeared with the first flower truss now appearing.

It was a plant I sowed early on when light levels were not too high so it has a thinner vine than some sown later. I'm not going to use this in the greenhouse (got better, stockier plants for that) but I will pop it in a container in the garden in a couple of weeks.

I put the purple leaves down to me splashing water on them before a cold night. If it is like mine then I wouldn't worry at all.

[starloc]

I have a book on growing tomatoes from the 1950`s, it says most times you get a potash shortage growing them they will need it added and that lack of potash shows up with purple stems, i had one with purple stems in places i fed it sulphate of potash, now its green no purple after a week

[teakdesk]

I agree starloc.

Plants do not get enough potash for two reasons....

1/ nutrients in the compost used up - possible, but most multi-purpose compost has enough for 4 to 6 weeks.

2/ the plant is too cold to absorb potash even though there is plenty there in the compost - happens often at this time of year.

Warmth and a weak feed are two excellent remedies.

[blackcatlois]

OK thank you all for your replies

[Maximillian]

I was wondering as I have the same thing! Will repot as they're on my windowsill and not big enough for outside yet.