A common issue we all deal with at some stage as gardeners is yellowing foliage. Take a look at the example pictured above, it's my own Trixzee™️ Miniature Peach tree which always looks amazing, lush and green each season, but, for some reason in the last 6 weeks it's turned a horrifying yellow colour. There are a number of possibilities.
To better understand what causes yellowing let's back up a little first and look at how and why plants are green.
Healthy plants produce chlorophyll, chlorophyll is the pigment responsible for them appearing green. Plants need to be green to be able to photosynthesise, it's how they harness energy from the sun to generate food for themselves.
Possibility #1 - Incorrect pH
If the pH is too high (Alkaline) or too low (Acidic) this will result in either 'nutrient lock up' an inability for the plant to access nutrients from the soil, or toxicity, essentially poisoning the plant.
Symptoms Not only might the plant appear yellow, but it could possibly have burnt crispy leaf margins, possibly be stunted in growth and overall, be performing poorly.
Remedy Determine the soil pH with a soil pH test kit and amend with either Sulphur if it's too Alkaline or Dolomite Lime if it's too Acidic to bring it back to within the ideal range recommended for the plant. Once the plant is back within its recommended pH range it will be better able to derive nutrients from the soil when you feed it.
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Possibility #2 -Hunger, lack of nutrients
Plants use a massive amount of energy and nutrients Nitrogen Phosphorus and Potassium (NPK) to grow and bear fruit and flowers.
Reason A plant may be hungry and lacking in nutrients due to it not having been fertilised, it's ran out of nutrients as it's taken up all that was there available, or perhaps recent heavy rains has leeched the nutrients from the soil. A lack of nutrients can be responsible for yellowing.
Remedy Apply a soluble fertiliser such as Seasol Powerfeed weekly to fortnightly alongside a quality organic pelletised fertiliser such as Neutrog Rapid Raiser.
The soluble fertiliser will benefit the plant by being taken up straight away, and the pellets will be taken in gradually as they break down.
Possibility #3 - Magnesium deficiency
Magnesium, a secondary macronutrient is a close runner up behind NPK (Nitrogen, Phosphorus and Potassium) in its importance to a plant, it's the central core ion of chlorophill. It also plays a vital role in the metabolism of phosphorus and is responsible for the uptake and mobility of water within a plant.
Sandy and acidic soils are more likely to be magnesium deficient.
Symptoms Yellowing between the veins (interveinal chlorosis) initially in the older mature foliage progressing to the younger foliage as well. The plant may also be slow in its growth and development, and the fruit or vegetable yield may be low.
Remedy Apply Epsom Salts (which is Magnesium).
Possibility #4 - Iron deficiency
Poor quality soils lacking in organic matter, heavy rain events or over watering, incorrect pH, or an imbalance of nutrients are all issues that could result in an Iron deficiency.
Iron deficiency is a common issue in acid loving plants, Hydrangeas, Blueberries, Rhododendrons and Azaleas.
Symptoms The new young foliage may appear pale yellow to almost white.
Remedy Apply chelated iron as per the instructions for rates on the label, it may take a couple of applications to see the plant green up again. Along with applying iron, aim to rectify the underlying issues that led to the deficiency in the first place. Apply sulphur or lime to bring the pH back to the preferred range for your plant if the pH was the issue. If your soil lacks organic matter, add compost, animal manures and mulch to feed and improve the quality of the soil.
Take a look at the image here below which shows the distribution of the yellowing. A visual cue might help you determine what's caused your yellowing.
Yellowing plants
It can be like solving a jigsaw puzzle trying to determine what's causing your yellowing. Climatic factors such as recent weather events, the type of soil you have, and pH or nutrient imbalances can all be responsible. Try using a process of elimination beginning with the pH to determine which it is.
Feel welcome to ask a question or share your experiences in the comments below.
Have a lovely weekend, and as always
Happy Gardening!😘🌸🌿
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