Spotting Plant Deficiencies in Plant Doctor

September 8th, 2021

PLANT DEFICIENCIES:

Imagine this scenario, you’ve fertilised your garden with all the right stuff, having followed the manufacturer’s instructions to a ‘t.’

But still the plants look sickly, or perhaps a bit yellow, or they’re just not putting on any growth.
Does that sound familiar?

  • So what’s the problem?
The first thing you need to do is a pH test on your soil-there's no escaping it.
Why?
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The soil pH will determine the availability pf different nutrients to your plants.

 
Let's look at an example
Looking at the chart on the right, it's immediately apparent that if your pH is higher than say pH7.5, then nutrients like iron start to taper off in their availability to the plant.
 
Then means your plant may start to show symptoms of iron deficiency.
In fact, after pH 7.5, other nutrients taper off in their availability, such as manganese, boron, and more importantly, one of the macro nutrients being potassium.

 

 
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Basic pH test kit

 

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    Ideally the ideal pH range that gardeners should strive for is pH 6 - 7.5

  • This is the range that the major nutrients of NPK are available to the plant the most.
  • Some plants such as rhododenrons and azaleas like a like a low of pH6.
A pH testing kit is essential in any gardener’s shed. Consider testing your soil in different parts of the garden.
A good tip when taking soil samples from your soil is to get a sample from just below the surface for an accurate reading.
 
First signs of Nutrient Deficiencies: 
Nitrogen: new leaves are pale green and older leaves are yellow and start to dry up.
Phosphorus: purpling of the leaves, particularly along the lower leaves. New leaves are a bit stunted and deformed in severe cases.  A bit more rare.
Potassium: poor overall health; older leaves turn yellow then crisp up and die off. Often mistaken for dehydration.
 
Let’s find out more about  pH testing and plant deficiencies 
I'm talking with Kylie Last, horticulturist and TAFE teacher.
If you have any feedback email realworldgardener@gmail.com or write in to 2RRR PO Box 644 Gladesville NSW 1675
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