Posted: Wednesday 25 June 2014
by Pippa Greenwood
Yellowing leaves, or chlorosis, is very common this year. It's often combined with slow growth, and vegetable plants seem to be most affected.
I often wonder if reading my blog posts is a bit like reading the problem pages at the back of a woman’s magazine. They involve a sort of fascination with things that are not quite as they should be, combined with a hope of finding the answer to your own problem.
Last time it was the dreaded potato and tomato blight, this time it's yellowing leaves. Harmless enough you may think, but believe me, it's very common this year – whisperings about it are reaching me wherever I go. People are asking me about yellowing by email, at gardening shows, and in even in the supermarket. Chlorosis, or yellowing, is often combined with rather slow growth.
Vegetable plants seem to be the most frequently affected, with runner and climbing French beans topping the list and courgettes following closely behind. In a funny way it's a relief for me to hear other people’s problems, as this year I’ve got them too. There is a distinct comfort in knowing that you’re not alone.
So what's it all about? Well, I’ve no doubt that most of it is down to winter wet. The excess soil water and pounding rain have caused many nutrients to leach out of usually fertile soil. Both nitrogen and magnesium are very readily leached, and these are the main nutrients linked with good green colour in the leaves.
Although I prefer to do most of my plant feeding in the form of a well-manured soil, this year I have been using some liquid feed too. If the yellowing is most prominent between the veins on the leaves, with the lower or older leaves being worst affected, it's also worth applying some Epsom salts to sort out a deficiency of magnesium. Neither job will take too long and it's essential to ensure good, green foliage or else plants, unable to feed themselves properly by photosynthesis, will soon start to deteriorate.