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What Leaves Tell You About Your Plant Health

By :tom bauer
What Leaves Tell You About Your Plant Health

The great thing about plants is that when they are feeling sick or stressed, they show us through their leaves. Knowing what to look for, and what to do, can stop small problems from developing and destroying our harvests.

There are three ways leaves show us that they’re unwell - colour, shape and damage.

These issues will be caused by environmental and physical factors, or nutritional deficiencies, as per the below diagram:

Pest problem

Pests can create holes in your leaves from eating them, as well as transfer diseases. Keep an eye out for mildew, fungus and bacteria which can all be transmitted to other plants. Click here for how to deal with pest problems.

Lack of Sunlight

Lack of sunlight can either cause a yellowing or fading of leaves along with leaves becoming droopy. Plants need a minimum of 4 hours of direct sunlight per day to avoid this.

Over / Under Watering

The best thing about your Airgarden is that the watering cycle is automated for you, so this is rarely a problem. However, watering cycles can be decreased from a 15 minute on / 15 minute off cycle to 15 minutes on / 30 minutes off if you are growing in very cold conditions.

Nutritional Deficiencies

Nutrient deficiencies can be the cause of many of the below leaf signs. The good news is that Airgarden nutrients contain all the macro and micro nutrients needed for your plants to avoid this. Nutritional deficiencies will display in the following ways:

However, if your pH is not balanced, your plants will not be able to absorb or utilise these nutrients effectively and may start to show some of the below signs. Remember to test your pH levels each week, and ensure it is between 6.0 - 6.5.

Leaf diseases


Leaf disease can occur from time-to-time affecting a number of different plants. They can affect both fruiting plants (like cucumbers, strawberries, and tomatoes) and leafy green plants (like herbs, lettuce, spinach).

The good news is that these diseases are relatively easy to spot, and if you catch them early, you can save your precious fruits and vegetables! The three most common leaf diseases that occur in Australia and may affect plants in your Airgarden are Powdery Mildew, Downy Mildew and Rust Fungus. For each of these, we outline below what to look for and how to fix it.

Powdery Mildew

What it does

Powdery mildew is a fungus which spreads a white or ash-grey film over the upper and lower surfaces of the leaves of plants; usually older leaves. Most common in high humidity and dry conditions, powdery mildew fungi block light to photosynthetic cells, so the plants are weakened in their ability to use light as an energy source.

How to fix it

1. Remove the worst affected leaves from the plant - this may help slow the spread of the disease by allowing more air circulation.

2. Apply eco-fungicide from ocp 

Eco-fungicide is a registered organic fungicide that rapidly kills external fungal growth and spores. It is effective on a broad range of plants and completely safe to use on fruits and vegetables.

You can buy Eco-fungicide online or at your local Bunnings.

Downy Mildew

What it does

Downy mildew can be identified from the fungal layer on the underside of the leaf. This fungus typically develops in moist weather and is accompanied by yellow spots on the top of the leaf, which may turn brown.

The fungus spreads by splashing water and the entire leaf dies quickly. Typically older leaves are affected first, then younger leaves.

How to fix it

1. Use wide spacing between plants to promote good air circulation and leaf drying.

2. Apply eco-fungicide from ocp

You can buy Eco-fungicide online or at your local Bunnings.

Rust Fungus

What it does 

Rust Fungus is a small, red or reddish-brown pustules that form on the underside of the leaves, destroying the leaf tissue and reducing the plant’s photosynthetic capacity. This fungus often results in poor shoot growth or leaf dieback, and in extreme cases plants may be killed by rusts.

How to fix it

1. Use wide spacing between plants to promote good air circulation and leaf drying.

2. Apply eco-fungicide from ocp

You can buy Eco-fungicide online or at your local Bunnings.

For all plants and pest related diseases, AusVeg is a great resource with an extensive list and additional information on the treatment of each issue. 

Also remember to always search out solutions that are recognised as having “no withholding periods”, which means you can spray your fruits and vegetables, rinse, and eat on the same day!

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