Chempak Foliar Feed

I'm not familiar with this particular product but epsom salts would probably be far cheaper.

If you water at about teatime or on a dull day, you won't have many problems with sun scorch.

Thank you for your responses.

I have looked for information on Epsom Salts. It seems to me that as a magnesium boost for tomatos its great, but according to all the write ups on epsom salts, it kills all beneficial organisms within the soil. So once you have used epsom salt the soil is useless and no good for plant growth and you therefor need to add all nutrients back by feeding. Tomato food doesnt have all the nutrients so its not a simple case of feeding tomato food once weekly but more a case of buying all these chemicals to add back to the soil or re-potting the tomatos 

I did see another forum user saying about spraying the epsom salt solution onto the affected leaves. As this wouldnt I assume have any direct effect to the soil, maybe its the safest way to use.

I still have my doubts tho. 

Chempak make a superb range of feeds, i use them all the time, but if i get yellowing leaves i get the epsom salts out.