Gardenia is nice-smelling, with beautiful flower, so lots of people like them very much; Gardenia lived in a sunny, moisture and fresh air environment without solarization. Appropriate spraying or adding ferrous sulfate can avoid yellows diseases. The yellows diseases of gardenia are caused by lots of reasons, so different measures should be taken: it starts from the old leaves, and extend to the new leaves. Leaves are little and crisp if lacking of N fertilizer; Old leaves turn to brown from green color if lacking of K fertilizer; Old leaves turn to purplish red or dark red if lacking of P fertilizer. Some thoroughly decomposed night soil or cake fertilizer should be applied.
Caused by Mg deficiency: The yellows extend to new leaves from old leaves gradually, but vein still keeps green, what’s the seriously leaves will drop. 0.7-0.8% boric magnesium fertilizer is needed to spray.
Caused by Fe deficiency: It shows on the new leaves, which is light yellow or white color with green vein, what’s worst, vein will turn yellow or white, and finally leaves wither and die. To this situation, two fertilizing methods could be taken:
One is fertilizing on roots: dilute some ferrous sulfate in the water or fertilize water, and irrigate trees or flowers directly, the thickness is 1-2%. Or put ferrous sulfate on the surface soil, let it absorb when watering and permeating. Fertilize 1g for 20cm flowerpot for the first time.
The other is foliage spray: dilute the fertilizer grade ferrous sulfate into water and spray it on the stem leaf, it will be absorbed by air vent on the leaves. The best time for spraying is in the morning or evening and there is no wind and rain. Volume is not too much, about 0.1-0.3%, the effect will be better if mixed with urea. Ferric citrate chemical agent has the same effect with ferrous sulfate. Too much water or frost also will arise the yellows, ferrous sulfate, growers should pay more attention to the details.