Yellowing tomato leaves

[willowman]

Have planted my toms in brand new growbags in the greenhouse. I water them regularly and they are about 12 inches tall. But the leaves and stems, from the bottom upwards, are starting to go paler green and turning yellow. Has anyone any ideas about what is wrong and what I can do to correct it?

[gumboil]

This is a typical symptom of Magnesium deficiency - the discolouration begins on the lower leaves and moves upwards until all the foliage is affected.It's a common disorder that's made worse, not better, by standard feeding. Some makes of growbags have very little nutrient value despite what they say on the bag.

Spray the plants with a solution of Epsom Salts at a rate of 0.5 ounces per pint of water. This is the specific cure for the problem and you should see a difference in a few days. To prevent the condition recurring, spray the plants with a foliar feed containing Magnesium once a week.

[Lonnie]

I was going to suggest Epsom Salts, but I see gumboil has done that, except I generally sprinkle it round the base of the plant, but both methods should do the trick.

[gumboil]

Yes, sprinkling dry epsom salts can work just as well.