Acacia cognata ‘Limelight’ is one of the best-selling wattle cultivars, and it’s easy to see why. With incredible, soft-swaying vegetation, the Acacia ‘Limelight’ adds a wonderful focal point in gardens, entryways and around fences.
Used often in tropical and traditional Asian gardens, this Aussie native grows well in pots and garden beds, accustoming quickly to poorer soil conditions, considering growing your own Acacia cognata at home?
Here is everything you need to know to cultivate, grow and care for Acacia cognata ‘Limelight’.
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What are Wattle Trees?
Wattles are incredibly popular, semi-deciduous trees that can be found almost anywhere in Australia. With their incredible ability to withstand harsh environments, Wattles or Acacia’s are the largest genus of flora across Australia.
These hardy inhabitants can thrive despite harsh winds, droughts, bushfires, and floods. 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. These hardy inhabitants can thrive despite harsh winds, droughts, bushfires, and floods.
Photo: Ivan Holliday on Flickr
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.
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A Must Have Complete Guide for Every Australian Garden
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
Source: pma.com.au
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.
Wrapping Up Our Acacia cognata ‘Limelight’ Growing Guide
If your goal is to grow lush, ornamental foliage, then the Acacia cognata is the way to go. Take care when establishing your cutting, ensuring you give it enough time to root and when replanting is very gentle with those roots.
Once established, your Acacia cognata hedge or shrub will just need plenty of sun and some occasional watering. Keep an eye on your soil to make sure it’s always draining adequately.
Follow these tips, and you’ll have plenty of beautifully growing Acacia cognata ‘Limelight’ all around your garden.
Published on January 12, 2023 by Nathan Schwartz
Last Updated on January 31, 2024
Can anyone tell me the life expectancy of Acacia Cognata green mist?
I am also interested to know the answer as I have planted a screening hedge of “copper tops”.
Thank you for the information on rooting cuttings. But I don't quite understand. It says to take a 10cm cutting, strip the leaves from the lower half, and then "…cut it down to 5cm" what does that mean?
Hi,
Thank you for your question! When propagating a cutting, you want to start with a longer, 10cm piece of healthy plant and then cut it down to 5cm just before you plant it. This is because as soon as you remove the cutting, the end starts to die off.
By removing an additional 5cm after you’ve spent time preparing the cutting, you put the freshest possible end into the soil to help improve the cutting’s chances of succeeding.
If you are working with a short cutting for any reason, we recommend keeping the cut end of the stem in water while you prepare it to help keep it fresh, or simply removing 1cm before you plant it rather than 5cm.
I hope that answers your question!
The AGT Team
I have several growing and don't know if they are just old and need replacing, or if I can transplant them. Most look very tired though one is spectacularly gorgeous and healthy. I will have a go at cuttings from that one.
1) What is their approximate lifespan in a suburban – previously neglected – garden?
2) The soil is poor there and I suspect builder's rubble underneath.
3) Are they worth pruning and transplanting?
4) Will transplanting damage roots? Is it safe to trim roots? I can't afford to put them in huge pots.
5) If potting, how big should the pots be? They are about a metre high with a lot of dead looking branches in the middle and sparse leaves on the end.
I only discovered your website today and I love it. Thank you for your straightforwad comments and suggestions,
Ismene
Hi Ismene,
Thank you for your questions!
Acacia cognata are short-lived but very beautiful plants, and those in the garden have likely simply reached the end of their lifespan, which is typically 10 years or less. They usually show this by dying off rapidly in large portions in their final seasons.
Their root systems are also very sensitive, so we don’t recommend transplanting them, and even a healthy plant can suffer or die if moved. The healthier one is possibly younger, and it’s definitely a good idea to take some cuttings.
These should be taken from the newest growth, dipped in rooting hormone solution or powder, and planted in small containers of loose of bark chips/native potting mix and river sand (or sand from where your current acacia cognatas are growing).
The mix should be kept moist but drain easily. Rooting can take 5-6 weeks, and you can transplant them once new growth starts to appear. If you are planting your cuttings into a pot, we recommend a container that has around 20 litres capacity to give the plant space to grow through its entire lifetime.
Again, it won’t need rich soil, and we recommend a mix of well-draining, low phosphate potting mix and river sand, and that you add a little native plant fertiliser in spring to support growth.
In terms of soil improvement, they actually thrive on neglect and poor soil quality, which is one of the great benefits of native plants! It may be a good idea to add some bark chips and compost suited to native plants when you replant the area, but too much nutrition can be bad for growth.
Just remember to water them well once a week or when the soil becomes dry while they are establishing their root system.
I hope that answers your questions!
The AGT Team
Thank you for the information.I just bought 140mm acacia limelight congrate.(27 plants)
How can I bring them up to 1.5m tall(standed)
Thank you
Perera.
Hi Perera,
Thank you for your question! Acacia limelight are traditionally compact, small and have a ‘weeping’ structure where it droops softly and elegantly towards the ground, growing to a maximum of 1x1m in a rounded shape.
Unfortunately, if you want your acacia limelight to grow tall (1.5-2m) with a distinct trunk, you will have to buy a standard as they cannot grow this tall trunk on their own. In a standard, this taller variety is created by grafting a budding acacia limelight onto tall rootstock from another plant.
This is how almost all standards are made, and while it sounds complex, it’s a process that has been around for hundreds of years, helping to change the shape of plants as well as creating healthier fruit-trees and vines.
When buying a standard acacia limelight, be sure to purchase one that is approximately the height you are looking for, as they are unlikely to get much taller.
I hope that answers your question.
The AGT Team
I have three Acacia Cognata green screen trees and one is loosing its leaves and the leaves are going brown before they fall, it has still some parts of it with leaves and now in spring it has flowers but not as many as the other two, it looks very bare, what can I do to get it back to health.
Hi Kathleen,
Thank you for your questions!
There are several reasons your acacia cognata may be looking poorly. The most common are:
•Age – These plants are not very long-lived and tend to have a lifespan of 10 years on average. When they get older, they will start dying off in larger and larger portions, turning brown and dying off with no clear cause.
•Fertiliser – As native plants, they’re well-adapted to get everything they need from poor-quality soil. Many fertilisers have phosphorus in them, and this can actually damage the tree’s growth and even kill the plant.
If you are using a fertiliser, be sure to use a native plant formula that is organic and very low in phosphorus to avoid this.
•Water – If your acacia cognata are well-established, they should need very little water other than rainfall and a top up during hot, dry spells. Too much water, especially if your soil is very clay-like and doesn’t drain well, will soak the roots and cause the plant to start dying off as the roots rot.
We hope that answers your questions!
Gary Clarke
My Acacia Cognata Limelight is going brown and brittle. What can I do as it does not need water.
Hi Sue,
Thank you for your questions!
There are several reasons your acacia cognata Limelight may be going brown and dying off. If it is getting enough water, then the most common causes are:
•Age – Unfortunately, acacia cognata Limelight are not very long-lived and tend to have a lifespan of 10 years on average. When they get older, they will start dying off in larger and larger portions each season, turning brown and dying off with no clear cause.
•Fertiliser – As native plants, acacia cognata Limelight is well-adapted to get everything they need from poor-quality soil. Many fertilisers have phosphorus in them, and this can actually damage the tree’s growth and even kill the plant.
If you are using a fertiliser for your acacia cognata Limelight or near it (where run off from rains can bring it in contact with its roots), be sure to use a native plant formula that is organic and very low in phosphorus to avoid this.
We hope that answers your question!
Gary Clarke
Hi my mini cog has gone brown on the top, what does this mean ?
Hi Michelle,
Thank you for your question!
There are several reasons your acacia cognata Limelight may be going brown at the top. These are the most common:
•Water – These native plants are very drought tolerant, so they tolerate low moisture levels well. However, if it is very hot and dry, they will need more regular watering – especially if your plant is growing in a container.
Another reason could be that it is actually getting too much water. If the roots are waterlogged and the soil is soggy, the plant will start dying off. Containers should have plenty of open holes (these can get blocked by roots) to drain all excess water easily.
•Age – Unfortunately, acacia cognata Limelight are not very long-lived plants and tend to have a lifespan of 10 years on average. When they get older, they will start dying off in larger and larger portions each season, turning brown and dying off with no clear cause.
•Fertiliser – As native plants, acacia cognata Limelight is well-adapted to get everything they need from poor-quality soil. Many fertilisers have phosphorus in them, and this can actually damage the tree’s growth and even kill the plant.
If you are using a fertiliser for your acacia cognata Limelight or near it (where run off from rains can bring it in contact with its roots), be sure to use a native plant formula that is organic and very low in phosphorus to avoid this.
We hope that answers your question!
Gary Clarke
I was given Acacia Limelight Standard in a pot forChristmas.It was shedding foliage & also had some thrip like insects on it.I sprayed it with Pyrethrum . The foliage is nw turning yellow & is brittle. Please advise can it be saved or have Ilost it already .
Hi Jennifer,
Most of the time when Acacia leaves turn crisp or brittle it’s due to overwatering. I know it sounds backwards, but if the roots are waterlogged, they just give up the ghost and stop carrying water and nutrients to the top of the plant.
If the leaves are also yellow, that’s another sign of overwatering. The pyrethrum spray shouldn’t have any negative effect on the plant, unless it was completely drenched in it. No plant that still has green inside its stems is a lost cause.
I’d suggest slowing down your watering, and if you have any long canes or spikes, drive them down through the root ball to create a sump for water to escape (if it’s in the ground).
All the best,
Gary Clarke
My acacia Cognata (green mist) standard, is about 6 years old, its trunk split about 4 years ago. It continued growing but its canopy spread. It is about 3 meters high and about 5 mts wide. It is very open. I would like to give it a heavy prune. How much can I take off?
Hi Jo,
You can cut Acacia cognata right back to about 10 cm above ground level if need be, and it should regenerate pretty quickly. All acacias tend to split eventually, it’s just the nature of the wood, but thankfully Acacia cognata is one of the more resilient when it comes to pruning back hard.
Obviously it depends on the shape, and the site of the split, where you actually cut but you’ll not be doing any harm in the process.
Best regards,
Nathan Schwartz
Hi,
I am hoping that you could provide me with some advice in relation to the Acacia Limelights.
I absolutely adore these plants & recently spent a good chunk of my savings in buying 10 of 140mm pots. I followed the instructions given to me by the sellers.
However, I am at a loss I believe. My plants’ foliage has dried up & turned brown. Have they borne too much sun or have they been overwatered? I am not sure.
Can I possibly revive them in any way?
I therefore seek your much needed advice & direction.
Many thanks in advance.
Hi Akhif,
Mature Acacia ‘Limelight’ will eventually just die, because they are short-lived plants like all Acacias. But it sounds like these were fairly new, and have only recently been planted?
My guess is that they haven’t fully rooted in, and a sudden burst of sun has dried them out too much, which is more likely than overwatering for young, newly planted, acacias.
Depending on their current state, you can try to revive them by soaking in water (if their root balls are dry).
If they are too wet, then lift them and let them dry out. It’ll quickly be apparent if they’re dry on top from overwatering as their roots will be black – in which case there’s nothing that can be done.
If you have pictures, or more info on the advice you were given when you got them, I’d be happy to offer more specific advice.
Good luck though, and I hope you have better luck if they recover.
Best regards,
Nathan Schwartz