A plant needs trace elements in tiny amounts, but a shortage shows immediately. That makes this group deceptive: the symptom is obvious and the cause usually lies somewhere else.
Measure your pH first, buy second
Iron shortage is the familiar picture: yellow leaf with the veins staying green, and unlike magnesium it appears at the top, in the young growth. But in most cases there is plenty of iron in the water and the pH sits too high to keep it available. Then a bottle is the wrong answer and feeding more makes it worse, because you are raising the concentration of something the plant cannot take up anyway. Measure with something from Measuring & Control and correct with pH Control before buying anything here.
One element or the whole spectrum
CANNA Fe IJzer Plus targets iron only and is chelated, meaning the iron sits in a form that stays available across a wider pH range. Trace Mix from the same brand tops up the whole spectrum: iron, manganese, zinc, boron, copper and molybdenum. If you know which element it is, take the single product; if you are unsure, the mix is safer than guessing at one.
The dose here is not a guideline
With these products the gap between too little and too much is narrow, and an excess of one trace element blocks uptake of another. Hy-pro Generator, for instance, is dosed at a fraction of a millilitre per litre, held level across the whole grow. Measure rather than estimate, and stick to the stated dose even when it looks like nothing. Generator also carries silicon; what that does is under Boosters.
Frequently asked questions
Is this not already in my base feed?
In a complete line, yes. These products are for when a shortage develops in spite of that base, for instance on soft water or after the pH has sat wrong for too long.
How do I tell iron from magnesium shortage?
By where it starts. Iron shows in the young leaf at the top, magnesium in the old leaf at the bottom, because the plant can move magnesium around and cannot move iron. See CalMag for the magnesium side.
Can I give too much?
Yes, and more easily here than with the main elements. An excess is also awkward to spot, because it presents as a shortage of something else. Stay on the dose on the label.
