June 30, 2022
Azaleas are a joy to see in any garden, but have you ever encountered the frustrating problem of the leaves turning pale green to yellow.
Many who have ever grown Azaleas will know that they like an acid pH. pH is the measured alkalinity or acidity of a soil. Most garden plants will require a pH of 6.5 - 7 for strong healthy growth which is just on the acid side of neutral (7). Azaleas on the other hand have special requirements and like their soil pH to be approx 5.5 - 6. Other plants that are compatible with low pH (5.5 - 6) are Camellias, Gardenias and blue flowering Hydrangea.
Iron deficiency rears it's ugly head when soil pH increases above 5.5. This is because Iron is more available at a lower pH, and as the soil pH increases, it becomes less available. If you have yellowing leaves on your Azaleas at home it can be easily corrected. First step is to ascertain that it is Iron that is deficient and not another element.
These are the specific symptoms of iron deficiency on azaleas:
Using specially formulated Azalea fertilisers will start the correction process. For Azaleas in gardens beds use Searles Azalea & Camellia Plant Food as per directions on the packet.
Searles Flourish Azalea Camellia & Gardenia Food is excellent for both plants grown in ground or in pots and containers. This soluble fertiliser is best applied at 2-3 week intervals, over the plant foliage and soaking the soil surrounding the roots. It not only promotes healthy growth of the plants, but it also contains chelated Iron, which helps to overcome the Iron deficiency, and it will help to acidify the soil, lowering the soil pH and promoting better plant growth.
For stubborn or extreme cases of Iron deficiency, also use Searles Iron Chelate in conjunction with one of the other fertilisers mentioned above. It can be applied to both the plant foliage and the soil and is readily absorbed by the plant, even if the soil pH is higher than desired.
Remember, whenever applying soluble fertilisers to avoid doing so in the sun or in very hot days over 30°c. They are best applied early mornings or late afternoons. When applying granular fertilisers, moisten the soil beforehand and water in straight afterwards.
Regular checks of pH will ensure problems like this one do not resurface.