Greening the Leaves - Gardening Australia (2024)

SERIES 25 Episode 34

Jerry explains how light affects leaf colour

"Gardeners often take the green colour of plants for granted," says Jerry. "That green colour is caused by a pigment called chlorophyll and chlorophyll allows plants to capture sunlight and convert it into food - it allows them to grow. But quite often, iron and magnesium - essential for producing chlorophyll - can be deficient in our soils. Those deficiencies can show up in two different ways."

"Iron deficiency first appears on new young growth and if those leaves grow yellow, there's a good chance you've got iron deficiency. To treat the problem, water in Iron Chelates (also called Chelated Iron) around the plants' roots - once in spring and once in autumn."

"Magnesium tends to develop on old leaves. If older leaves grow yellow, but the young leaves remain green, magnesium is the key suspect. Magnesium is very water-soluble, so you can treat this deficiency by applying Dolomite at the rate of one handful per square metre in autumn - that will last the plant right through a year. However, in tropical climates with heavy rainfall it's better to use Epsom Salts (Magnesium Sulphate) as a spray. Dilute one teaspoon of Epsom Salts in a litre of water and you can spray that over foliage once a month during summer."

"If you put those two treatments together, you're plants will be greener than green and they'll be super efficient at capturing that sunlight and converting it into growth!" Jerry ends.