Help my plants are all turning yellow

[joinerjim]

Hi everyone,

I have just noticed all my tomato plants, cucumbers, melons and aubergine are all starting to turn yellow on the leaves. All the plants are in grow bags except the cherry toms which are in tomato pots. I water in the evenings and at the moment watering every other day. I water using rain water from a butt attached to the greenhouse gutter. I have peppers but at the moment they don't seem affected. Any ideas anyone ?

[rainbowgardener]

Yellowing leaves is a common symptom, which can be caused by different things. Some pictures would help.

In the meantime my first thought is the grow bags might be holding too much water. Have you checked to see how wet it is inside them? Overwatering can produce yellowing leaves. Here's a little bit about overwatering:

The symptoms of overwatering usually start with the plant looking a bit wilted, particularly during the warmest part of the day, although they usually regain some turgor at night. This can induce a cycle of more overwatering as the grower assumes a wilted plant is not getting sufficient moisture. Pale green or yellowing on the youngest leaves also suggest overwatering, as iron is the first element that a water-damaged root system fails to take up in sufficient quantities.
https://www.growingedge.com/magazine/back_issues/view_article.php3?AID=180544

Along with cutting back the watering if this seems to be the issue, you can add a bit of ironite, which helps the plants green up again.

If leaves on the whole plant are pale yellow, this can be a symptom of nitrogen deficiency. If you've mulched with bark or leaves, especially if they've been turned in to the soil, it can use up a lot of nitrogen trying to break it down. In which case fish emulsion or other nitrogen sources should help.

Here's a source about problems in tomatoes, but it gives a list of different symptoms and what might cause them that seems helpful https://yardener.com/YardenersPlantHelper/VegetableGardening/VegetableFiles/Tomatoes/ProblemsofTomatoes

[Gary350]

Did you mulch with wood, bark, sawdust or some other type carbon? Mulch sucks all the nitrogen from the soil and from the plants too and the plants die. There is a name for this I don't remember what it is called.

[rainbowgardener]

Seven years later, I doubt jim is holding his breath!