What is the prefered potassium for Azaleas?

Answer 1

Potassium (chemical symbol 'K') is one of the three principle nutrients needed for healthy plants, including azaleas. [The other two nutrients being nitrogen (N) and phosphorus (P).]

Potassium occurs naturally in many soils, but if an azalea is suffering from potassium deficiency, a suitable azalea fertilizer containing N+P+K can often restore the necessary potassium balance.

Plants normally get K from potassium compounds in the soil. Azalea fertilizers containing N,P,K are used to encourage root spread, and for proper growth and development, but the percentages of N,P,K in the fertilizer can be varied to correct or supplement specific soil deficiencies.

One source of K is glauconite, a naturally occurring mineral found in greensand. The K compound in it is potassium silicate. Greensand also contains other trace elements important for plant health. This is why it is commonly used in fertilizers.

However, there are a number of potassium compounds and potassium-containing materials that plants can utilise for their potassium needs. All are water soluble and thus ideal for root or leaf absorption.

Potash fertilizers, for example, may contain one or more of the following suitable potassium compounds: potassium chloride; potassium magnesium sulfate; potassium nitrate; and potassium sulfate, all or any of which can readily be metabolised by azaleas and other plants. Manure is also a source of potassium for plants.

Regardless of the potassium source, the biggest danger is 'over-fertilizing', which will kill the plants. So it is important to undertake proper soil and plant analysis before administering potassium-based fertilizers to azaleas. Proper soil testing and correct identification of the signs of the plant's potassium deficiency will help to indicate or predict which NPK-mix percentage is best for your plants.

Then...

1. carefully follow the dosage, method of application, and timing instructions
2. monitor the results regularly; and
3. make adjustments as necessary.

But remember, many soils are already rich in readily available potassium, so the application of potassium fertilizers may not be necessary, unless, of course, depletion of available potassium around the azalea has developed over the years. Soil tests from a number of places around the plant are therefore essential in revealing any potassium deficiencies and the extent to which this may be so.