Oops! What about those yellow leaves?
And you where thinking that plants had nothing to say?
When something in their environment or diet is getting out of balance, then they have enough to say. Sometimes they actually scream, in silence.. It is very important to know what a healthy plant should look like; otherwise the early warning sings can be overlooked.
The actual name for yellowing leaves is ‘chlorosis’. In the open ground or in standard potting soil the yellow leaves can be caused by dry soil. In hydroponics it usually means that something is wrong with the nutrient solution. As we all know, a deficiency in your nutritional needs ensures that you will look a little lifeless, or that you just miss the energy for daily activities.
With only saying that the leaves are yellow, is just not enough to determine exactly what can be wrong with a nutrient solution. What kind of yellow is it, and where are those sad-looking leaves on the plant? Hopefully the discoloration only appeared recently, because untreated symptoms are a harbinger of more serious problems with your plants.
Smooth yellow leaves are often a result of a nitrogen deficiency (N), but the first signal of this is that the plant is lighter green than it should be. The plant exhibits an upset growth, most clearly visible in the tops and side branches. Also they will be thin and fragile looking. The deficit starts at the old leaves low on the plant and slowly moves up to the younger leaves. Plants lose their adult leaves early with a nitrogen deficiency, similar to problems caused by too dry roots.
Yellowing between the veins also occurs at a nitrogen deficiency as the leaves change colour form light green to yellow, but this can also be a sign of a potassium deficiency (K). A too low level of potassium will cause the yellowing only on parts of the leaf and be accompanied by scorched-looking places. The scorching or necrotic spots start at the edge of the leaf and ultimately moves inside. If the circumstances last, the symptoms will climb up to the he younger leaves.
Yellow spots between the leaf veins are a common phenomenon of an iron deficiency (Fe). Unlike the two previous problems, the spots first disappear on the youngest leaves. In the event of a serious iron deficiency there can be a complete absence of chlorophyll, without spots. This starts at the base of the new leaves and looks like a central yellow stripe that is slowly spreading.
Also there are other causes of yellow leaves, as a sulfur deficiency and early stages of some diseases. Each cause has its own unique symptoms. You should check all your plants regularly. If you see something strange on the plant, it is a good idea to identify and to address the problem as soon as possible.
Or even better, just test your nutrients regularly with suitable measuring equipment to obtain accurate measurements of all essential substances and micronutrients. If you are not sure of what you need, search this than from different plants. Hopefully you realise that.