Owner of Caloundra Garden and Pet Supplies
IF YOU have fertilised and the leaves of your plant are still looking yellow instead of green, then your soil could be deficient in one or more trace elements.
Some of the major nutrients that a plant needs are nitrogen, phosphorus, potassium, but here are heaps of other elements that your plant needs as well and these include, magnesium, iron, copper, zinc, boron, molybdenum and sulphur.
Gardenias frequently have yellow leaves and it is often a lack of magnesium, but with citrus it could be magnesium or it might be lacking in Iron. Copper deficiency makes leaves go yellowish and a bit pink and if your plant is lacking in sulphur the leaves can go a pale yellow, and to make it even more difficult to diagnose the colour and patterns on the leaves can look different on different plants and it can also look different depending on how much your plant is lacking.
If you know what your plant is lacking that is great, you can buy magnesium, Iron, and many other trace elements separately, but if you are unsure what to use then get a trace element mix.
A trace element mix has magnesium, iron, copper, zinc, boron, molybdenum and sulphur. All these elements will help balance the soil so you have the right nutrition. Trace elements are like multi vitamins, you may not need to use every week, but it is a great way to keep your plant in tip-top condition.