Acacia cognata ‘Limelight’ | Growing + Care Guide Australia

What are Wattle Trees? 

Plus, with dense, evergreen foliage, they’re fantastic feature plants too. Many say that their resilience is a direct representation of the spirit of the Australian people. 

Getting to Know Acacia cognata

Acacia cognata is a species of the Fabaceae family and is native to Australia. It is known by the common names bower wattle, river wattle, or narrow-leaved bower wattle.

Mainly found in south-eastern Australia, this tree can grow to a height of 8m and 4m wide. It has a distinctive weeping habit and long narrow lime green leaves. 

One of the prettiest cultivars of Acacia cognata is Acacia cognata ‘Limelight’. Acacia ‘Limelight’ grows to a maximum height of around 1m and spreads to a width of up to 1.2m. This river wattle is an evergreen and looks fantastic all year round. 

When established, Acacia cognata ‘Limelight’ is relatively drought tolerant. They can also withstand light frost.

The most popular Acacia cognata include: 

• Acacia ‘Mini-Cog’. A very small cultivar, great for indoors. 
• Acacia ‘Bower Beauty’. A colourful cultivar offering an attractive bronze and orange growth at the tips. 
• Acacia ‘Lime Magik’. A weeping, willow-style cultivar growing only about 1 metre in height. 
• Acacia ‘River Cascade’. Stunning as a landscaping feature and suitable for hedge growing. 
• Acacia ‘Green Mist’. Beautiful and bright, ideal as a focal point in gardens.

How long does it take for Acacia ‘Limelight’ to grow?

Acacia cognata ‘Limelight’ is a fast-growing plant. This makes it a popular choice for gardeners and landscapers. Given Acacia ‘Limelight’ is a dwarf Acacia cognata cultivar it won’t grow to an unwieldy height and will remain a compact plant, especially if pruned consistently.

When does Acacia ‘Limelight’ flower?

Acacia ‘Limelight’ looks great all year round. The lush, lime green, weeping foliage is the star of the show and the main attraction of this Australian native. 

This cultivar doesn’t flower prolifically but you may get some small, yellow, globular flowers. Like most wattles, Acacia cognata ‘Limelight’ flowers in late winter and early spring. The flowers on Acacia ‘Limelight’ will be quite hidden by the plant’s long leaves but look for them from July through to October.  

When flowering, Acacia ‘Limelight’ are a great source of pollen, making them very popular with bees and other native wildlife. 

How to Grow Acacia cognata ‘Limelight’

The Best Soil for Acacia ‘Limelight’

This river wattle dwarf grows well in a wide variety of soils. While they can do well in clay soil, they prefer well-drained sandy soil. Like most native plants, Acacia ‘Limelight’ is used to low nutrient Australian soils so it isn’t strictly necessary to add fertilisers or other organic material to the soil, for the plant to thrive in your garden. 

Where to Position Acacia ‘Limelight’ in Your Garden

Acacia ‘Limelight’ will happily grow in shade or full sun. As noted above the weeping Acacia cognata ‘Limelight’ prefers well-drained soil. If possible, find a sheltered spot in your garden, where the Acacia ‘Limelight’ will get some protection from strong winds. 

Acacia ‘Limelight’ is a popular and versatile plant for your garden. They can be mass planted or serve as a feature shrub in gardens, rockeries, or even container pots.

Gardeners also use them as ground covers, border plants, along fence lines, or as low hedging plants. Their distinctive lime green foliage really pops and contrasts well with other common plants in the garden. 

These dwarf river wattles are perfect partners for other native plants like Eucalyptus erythrocorys (Illyarrie). Mass plantings of the weeping Acacia ‘Limelight’, as a ground cover under a group of eucalypts, can look fantastic. 

While they are very hardy plants, you will want to ensure your Acacia ‘Limelight’ is protected from the elements when still establishing themselves. 

Propagating Acacia ‘Limelight’

Propagation through cuttings is the easiest and most effective. These cuttings should be taken in the spring or in early autumn, as colder conditions may affect the ability of your Acacia ‘Limelight’ to take root. 

In general, cuttings taken during warmer conditions have an 80% success rate. More so, you can take multiple cuttings at once to propagate plenty of smaller plants. 

Simply: 

• Remove a healthy branch close to the tip, approximately 10 cm in length. 
• Strip the lower half of the foliage and cut it down to about 5 cm in length. 
• Stick the cut edge into a seeding tray with a rich potting mix to root.

For rooting, you will want to use denser potting soil. A mixture of perlite and coconut coir is recommended. 

Rooting will take as long as 2 to 3 months. Ensure you are watering your cuttings regularly and giving them bright, indirect sunlight throughout the day. 

Growing Acacia ‘Limelight’ in a Pot

It’s important to wait long enough before re-potting your cuttings as they have incredibly sensitive roots. Remove your cuttings carefully from the seeding tray and gently plant them into a pot. 

As A. cognata plants grow naturally in poor soil conditions, you can use a native mix of organic compounds for your soil. 

Try to keep your pot in a spot that is warm and gets plenty of indirect sunlight. In the early growing stages, cuttings can be negatively affected by too much direct sunlight. However, too little light will also prevent growth. 

It is recommended to leave your growing A. cognata in the pot for at least 3 months before transplanting it into a bigger pot or garden bed.

Caring for Acacia cognata

Acacia cognata care really doesn’t require much once the plant is established. This particular cultivar will maintain its exquisite lime green colour, even in times of drought.

So, when it comes to watering, you won’t have to worry much. Should you experience a season with particularly low rainfall, consider supplementing with some additional water once a week. Otherwise, your Acacia ‘Limelight’ will get all the water it needs from the natural rainfall. 

It’s also always a good idea to support your cognata with some additional fertiliser during springtime, which will help boost growth. Any native fertiliser will do the trick. 

Pruning Acacia cognata

Pruning will be the only laborious aspect of care. Pruning can be done to promote plant health, vigorous growth and maintain shape and size. 

How much you will want to prune your cognata will depend on where you’re growing it. For instance, for an Acacia cognata hedge, you will want to prune more regularly to ensure the right shape and size. 

In general, you can cut back as much as half of your Acacia cognata hedge using a sterilized pair of garden shears.

Acacia cognata ‘Limelight’ Pests, Problems & Diseases

This cultivar is relatively pest and disease-free, meaning you won’t have many issues throughout your growing journey. The only issues some growers have experienced is with red spider mites and mealybugs. Luckily these are easily treated with an organic, horticultural spray or neem oil. 

Worms, caterpillars and borers may also take favour to your Acacia ‘Limelight’. The most common pest you may encounter is the incredibly invasive shot hole borer. You will need to undertake immediate reactive treatment, as these garden pests tend to spread. 

Common Wattle Problems

While it’s not specific to the Acacia ‘Limelight’, many wattle trees are highly susceptible to root rot or Phytophthora cinnamomi. This highly intrusive rot attacks the tissues of the plant, causing it to wilt and eventually collapse. 

Unfortunately, there isn’t much you can do to treat this kind of rot and it’s best to remove an infected plant before it can infect the rest of your garden. Be sure to sterilise and clean any materials used to remove the tree in order to avoid cross-contamination.

Acacia cognata Frequently Asked Questions

Why is Acacia cognata called ‘Limelight’?

A. cognata gets its common name from the frosted, lime green glow that passes through its delicate foliage in the afternoon. While its foliage is typically grassy-green in daylight, direct sun passing through the thin leaves highlights the vivid and plentiful chlorophyll in the leaves, creating a stunning lime green glow.

Is Acacia cognata native to Australia?

A. cognata is native to Australia, specifically south-eastern Australian, where this wattle can be found growing in abundance in the wild. The seeds self-sow fairly easily on southern soils, and can germinate readily beneath the weeping branches of their parents.

What can I plant with Acacia cognata?

Acacias can be grown as shrubs or small trees, depending on your location, but as a fairly short-lived plant, they benefit from other shrubs, small trees, or tall perennials around their base.

In moist soils, planting hungry plants around their base helps to manage soil conditions, and create a slightly drier environment for them. Try growing Azaleas, Hydrangeas, or Camellias alongside your A. cognata.

Where is the best place to plant an Acacia tree?

Acacia trees are best in well-drained soil, in full sun but some protection from the wind. The main problem with growing Acacias is their brittle stems, which are easily damaged by high winds, so with their relatively non-invasive roots, it’s worth planting them near the house, or with some structural protection to help them live longer.

What is the lifespan of Acacia cognata?

A. cognata tend to live for about 30 years. They are incredibly fast growing, and all of that energy simply exhausts the tree in time, putting pressure on their brittle limbs, and exhausting their roots.

With good wind protection, and light irrigation on well-drained soil, some Acacias have been known to live much longer.

Is Acacia cognata fast growing?

A. cognata is fast growing, and can put on around 50cm-1m of new growth each year, reaching its full height of 4m in just eight years. Acacias, and A. cognata are particularly useful when speeding up the establishment of new gardens.

How deep do Acacia cognata roots go? 

A. cognata roots can reach as far down as 15m into the soil, but rarely do in cultivation thanks to compacted garden soil, and poorer drainage. However, as fast growing, short-lived trees, they do not pose any real threat to structures and their roots will usually just grow around, rather than through their surroundings.

Can Acacia cognata grow in shade?

All Acacias, A. cognata included, prefer to grow in full sun, but they can be cultivated in surprisingly deep shade. In nature, they germinate under the shade of their parents, so are well adapted to these conditions, but the stronger seedlings out-compete their parents, and tend to grow through in search of full sun in the end.

What are the benefits of planting an Acacia tree?

Planting Acacia trees help to nourish the soil by fixing nitrogen at their roots, and pulling nutrients in from far and wide. Planting an Acacia in a garden with poor soil helps to improve the soil for new planting, and eventually, your planting will outlive the tree but remain with the legacy of improved soil.

Is Acacia cognata messy?

A. cognata is a fairly clean tree in terms of leaf-drop, but the constant dropping of seed pods can be a problem, requiring regular sweeping to avoid constantly Acacia saplings from germinating in your lawns and borders.

Can Acacia cognata survive winter?

There are some species of Acacia that can survive a light frost, A. cognata included. Prolonged frost and temperatures below 0°C will kill A. cognata though, so protect them from frosts that last longer than a single night.

Do ticks live in Acacia cognata?

The wattle tick scale is a scale insect, rather than a tick, but it does closely resemble common ticks. They are not harmful to humans, but can badly affect A. cognata if infestations get out of control.