Macro Nutrient Deficiencies: Symptoms and Fixes

 PLANT HEALTH

Plant Nutrition Deficiencies: Macro Nutrient Nitrogen

The 'Plant health' segment was created for my radio show "Real World Gardener,' as a division of the 'Plant doctor' segment, because I felt that it’s important to focus on what can go wrong with plants that isn’t a pest or a disease.
In the following audio podcasts, you will hear about what to look for in plants that have deficiencies of one of the macro nutrients: Nitrogen:Phosphorus:Potassium; in other words NPK or the macro nutrients.

Gardeners can often see problems appearing first in the colour of the leaves, but this can also be followed closely by lack of vigour, stunted growth and general unthriftiness of the plant.

The key to diagnosing problems, however isn't just looking at the colour of the leaves but it's knowing your soil type and soil pH.

Yes, I know, we do go on about soil pH but that often underlies the reason behind your plants' problems.

The other underlying problem may be insufficient drainage which causes waterlogging of the soil.

That said, we  will assume that you soil pH is around 6.5 - 7 but your still seeing issues that are showing up in the leaves. So what next?

Macro Nutrient Nitrogen

Nitrogen is one of the three big nutrients or macro nutrients that plants need.

Nitrogen is responsible for leaf growth and blossom formation.

First Symptoms: Oldest leaves start to appear pale first, yellowing at the leaf tips then eventually the whole leaf will turn yellow.

Quick Fix: Soluble fertiliser high in nitrogen. 

Results should appear in a few days.

Long term fix: Blood  n' Bone and/or controlled release fertilisers.

Nitrogen on it’s own can be useful for quick greening of lawns and leafy plants like ferns in pots when the potting mix is depleted of any nutrients.

Listen to the podcast: I'm talking with Kylie Last horticulturist and tafe teacher.

Plant Nutrition Deficiencies:Phosporus and Potassium

We have talked bout the role nitrogen played in played health and what to look for if a plant was deficient in one of the major nutrients, being Nitrogen.

• In fact there are three major nutrients which are classified as NPK ratio on the back of all fertilisers. So in this part of the blog, we carry on with the two other major or macro nutrients.

Let's look at phosphorus deficiency

Phosphorus is responsible for the development of flowers and fruits and roots.

• Phosporus is known as a mobile nutrient which can move around the plant to where it's needed.
• Phosphorus deficiency happens more often in cold weather or gardens receive high rainfall, or a combination of both.
• Often affects heavily fruiting plants such as citrus.
• N..B. native plants are highly sensitive to phosphorus, so avoid spreading phosphate fertilisers near these plants.
  
  
  

First Symptoms: Older leaves become quite a dark green then develop a purplish tinge.

 

Tips will then dry off. Not to be confused with lack of watering especially in pot plants where leaves can also develop dry tips.

Overall growth is affected in the long term resulting in smaller leaves and stunted growth.

Quick Fix: Fertiliser high in phosphate either solid or liquid.

Long term fix: Blood  n' Bone and/or controlled release fertilisers. 

Let's look at potassium deficiency

Potassium is responsible for thickening of cell walls, and also responsible for plant growth. Potassium deficiency are more evident in flowering or ornamental plants. Potassium deficiency often is a pH issue in the soil.

First Symptoms: Older leaves become brown and dry on the upper surface, with leaf edges puckering slightly. 

As the deficiency progresses, the leaves darken in colour between the veins.

Flower stalks become thin and spindly and may be quite short.

Fruits may fail to develop full colour and flavour.

Quick Fix: Fertiliser high in potassium either solid or liquid, such as sulphate of potash.

Long term fix: Blood  n' Bone and/or controlled release fertilisers. 

Listen to the podcast: I'm talking with Kylie Last horticulturist and tafe teacher.



I would recommend becoming familiar with the NPK ration on fertilisers, whether organic or not to see if you’re applying the right sort for your plants.

For example, fertilisers that promote flowering and fruiting have higher ratios of potassium than those that are just for general purpose fertilising.
If you have any questions you can email us Realworldgardener@gmail.com or write in to 2rrr, PO Box 644 Gladesville NSW 1675.

Plant Nutrition Unpacked: Plant Nutrients and Deficiencies

 PLANT NUTRITION UNPACKED

Major Nutrients

Have you ever asked yourself "how do plants take up nutrients when you spread fertiliser around them on the ground or dilute it into liquid ?"

It's something that we gardeners do quite a lot of,  spreading fertiliser around that is, and probably don't give it a second thought until plants don't respond to all this nutrient load.

• What went wrong? 

Firstly, the nutrients that you spread around are not directly taken up by the plants.

Nutrients have to be what's called 'made available' to the plants and to do this, the soil biota or the microorganisms have to do some work.

Water, soil and microbes are the three things that the plants need before plants can take these nutrients.

• So What Are These Nutrients?

Macro Nutrients:   these are the highest rated nutrients that plants can’t do without.

• Nitrogen:Phosphorus:Potassium or NPK: 

  

  A selection of fertilisers

• Kylie's main mantra is NPK refers to shoots:roots;fruit

The N component relates as Nitrogen, giving your plant nice healthy green leaves.

The P component: encourages healthy root systems.

The K or potassium component helps the fruits and flowers

Sure we can add compost, aged manures and liquid seaweed, but unless you’re sure of what’s in them nutrient wise, you may be under fertilising your plants.

Without the major nutrients, your plants may not grow and develop roots, stems leaves and flowers properly.

If you know what and how much to give your plants, the plants will be healthier and more productive.

Just remember to read the NPK amounts on the bag or packet of fertiliser.
Let’s find out more about what plants really need.
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

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?

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.

Basic pH test kit

 

• 
  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