The telltale sign of magnesium deficiency is chlorosis – that is, the leaves of the plant becoming paler and paler, turning yellow and sometimes brown. It will show up in lower, more mature plant growth and then begin to spread. While being unsightly to the veggie patch and lowering the overall colour tone of the garden, magnesium deficiency will also stunt plant and fruit growth.

Typically a result of wetter- and cooler-than-usual conditions, it will also be more prevalent in acidic soils, so testing of your pH is advisable if you start to notice your leaves turning. It will also target those plants that require high levels of potassium to produce fruit – such as tomatoes and citrus – that will make magnesium unavailable.

Optimal Conditions

It will mostly affect warm season plants during the cooler, wetter times of the year


Yellowing leaves on the lower, more mature stems of the plant


Consistent watering practices and routine testing of pH. Worm castings and juice are both great soil conditioners that allow easier passage of nutrition in the soil to the plant. Incorporate sparingly in the patch.


Keeping plants properly watered and mulched allows greater access to the nutrients within the soil. Warmer-season plants tend to slow their uptake of water and nutrients when temperatures drop, so it is most common for leaves to turn yellow in cool conditions. Once soil temperatures increase, they begin to repair.


An application of Epsom salts to the foliage and the roots will quickly begin to repair the plants as they absorb the salts.

Related Products

All Purpose Plant Food 2.5kg
Regular price $14.00
pH Testing Kit Manutec
Regular price $31.00
Special instructions for seller
Add A Coupon

What are you looking for?

Join Our Community

For seasonal tips, planting advice, special offers...and to get your fingernails dirty