I have 2 big leaf rhododendrons that have chlorotic leaves. From what I have read I think I may need to add sulfur. Do you recommend ferrous sulfate for this and should it be added as a dry or liquid amendment?
Multnomah County Oregon horticulture
Just adding sulfur is not the best approach, sulfur effects soil Ph and without checking the Ph first could be disastrous. Clorosis at the leaf margins is a sign of nitrogen deficiency this can be due to soil Ph or just depleted soil.
I recommend fertilizing with AMMONIUM SULFATE if you plan to check soil Ph do so before applying the fertilizer. The Ph can also be tested after fertilizing but allow enough time for the fertilizer to work.