Jacaranda Tree Problems and What to Do About Them

Like most plant lovers, I simply adore the majesty of a large Jacaranda tree in full bloom. Their colour and form cannot be ignored as they put on their glorious floral display.

Even a Jacaranda that has finished blooming look fabulous with its delicate fern-like foliage as it provides shade on a hot summer’s day.

Although mature Jacaranda trees suffer from very few problems, there are a few things that you should look out for especially if you have a young tree that has not yet fully established itself in your garden.

Aphids and scale insects

Scale insect | Plant care

While mature jacaranda trees won’t be affected too much by sap-sucking insects such as aphids and scale insects, young trees may suffer a little damage.

What to do

Aphids can be removed by giving them a good blast of water from the hose. Alternatively, you can spray your tree with a natural product such as white oil or neem oil that you’ve mixed with water.

However, unless they’re in huge numbers, it’s better to wait and see if you have some ladybirds come to your garden to take care of these pests for you.

Scale insects can easily be wiped off with a damp cloth or a cotton bud dipped in isopropyl alcohol. This is the most natural way to remove these pests from any plants in your garden.

However, spraying your young tree with a mixture of neem oil and water can also help to control these pests, especially if they appear in large numbers.

Sooty mould

If you have had problems with aphids and scale insects on your jacaranda tree, you might also notice that some of the leaves and branches are covered with a black mould-like substance.

Sooty mould | Plant care

This is commonly known as sooty mould and is caused by the sticky substance secreted by sap-sucking insects known as honeydew. 

What to do

First, you have to get rid of the sap-sucking insects that are causing the sooty mould. The black mould itself can easily just be wiped off with a damp cloth.

You might have also noticed your jacaranda has ants crawling on it. These ants will be attracted to the honeydew that is secreted by the sap-sucking insects.

The ants won’t do any damage to your tree and will disappear once you’ve taken care of the sap-suckers and wiped off all the sooty mould.

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Leaves turning yellow

If the leaves of your jacaranda are turning yellow, the tree is most likely suffering from a lack of water.

Jacarandas need to be watered quite deeply so that the moisture reaches down to their extensive root system.

What to do

Give your tree a really good deep watering, primarily at the soil level.

This might involve placing a hose (without an adaptor) or sprinkler at the base of the tree and letting it run for around an hour so that the water can seep right down into the soil.

You might need to do this every couple of days for around two weeks in order for the entire root system to become totally replenished.

Keep in mind that it could take around 6 months or more for the tree to fully recover.

RELATED: Full-Grown Moringa Trees: What do They Look Like?

Problems caused by too much fertiliser

Like most mature trees in your garden, your jacaranda tree should not require copious amounts of fertiliser.

In fact, too much fertiliser can cause damage to trees resulting in dying leaf tips.

This is due to the salt and mineral build-up in the soil from constant fertiliser applications.

What to do

Water deeply around the base of the tree in order to flush the excess salts and minerals out of the soil.

Lack of flowering

If your jacaranda is not producing an abundance of blooms, it could be because you’ve applied too much fertiliser that’s high in nitrogen.

Nitrogen is responsible for producing lots of green growth and this means that the tree is putting all of its energy into growing foliage rather than producing flowers.

What to do

Water the soil at the base of your jacaranda deeply in order to flush some of the nitrogen away. Don’t fertilise your tree until it has finished flowering if at all.


Is the Jacaranda tree an invasive species?

In some parts of the country, the Jacaranda is considered an invasive species because it has an invasive root system that can go quite deep into the ground.
When this happens, it can easily crowd out the root systems of native species, as the Jacaranda will greedily take all the moisture and nutrients in the soil for itself.
According to the Brisbane City Council, Jacaranda mimosifolia is regarded as an environmental weed in both NSW and Queensland.

Photo of author

Annette Hird

Annette Hird is a gardening expert with many years of experience in a range of gardening related positions. She has an Associate Diploma of Applied Science in Horticulture and has worked in a variety of production nurseries, primarily as a propagator. She has also been responsible for a large homestead garden that included lawn care, fruit trees, roses and many other ornamental plants. More recently, Annette has concentrated on improving the garden landscape of the homes that she has lived in and focused a lot of energy on growing edible plants as well. She now enjoys sharing her experience and knowledge with others by writing articles about all facets of gardening and growing plants.


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