How to maintain healthy lilly pillies

Safety tip: Always wear the appropriate safety equipment (safety glasses, gloves, and a mask, for example) and always follow the instructions for the product or equipment. Always wear gloves and a mask when handling potting mix, mulch and compost, and store products out of the reach of children and pets.

Potential problems

With proper feeding and watering, lilly pillies are generally hardy and can resist most pests and diseases.

One of the most common insects that might pose a threat to your lilly pillies is the lilly pilly psyllid, a sap-sucking insect. The newly hatched larvae feed on the tender new leaves, causing deformations that look like pimples or bubbles. To combat them, keep a keen eye out for any signs of their presence. If you spot them, act swiftly and prune all the damaged foliage immediately. It's important to dispose of the pruned leaves in a sealed bag to prevent any potential re-infestations. It's worth noting that, while Syzygium australe varieties are particularly susceptible to psyllid attacks, the ‘Straight and Narrow’ and ‘Backyard Bliss’ varieties have been carefully bred to be highly resistant.

Another sap-sucking pest that might threaten your lilly pillies is scale. These insects feed on the sap from stems and leaves, potentially causing severe damage. They can even kill your plant if left unchecked. A tried-and-true remedy is the application of white oil. By diligently applying this treatment, you can safeguard your precious lilly pillies from the effects of scale infestations.

Leaf problems

Black leaves

Monitor the leaves of your lilly pillies for potential issues. One common concern is the appearance of black leaves, which can be caused by a fungus known as sooty mould. To address this problem, use neem oil or concoct a homemade solution using household detergent (1 teaspoon per litre of water). Apply the mixture to the affected areas and let it sit for about 15 minutes before rinsing it off with a strong stream of water from your garden hose.

Yellow leaves indicate a potential nutrient deficiency or overwatering. To remedy this, make necessary adjustments to your watering routine and apply a balanced fertiliser if needed. This ensures your lilly pillies receive the right balance of nutrients and moisture to foster healthy growth.

If you encounter chomped leaves, the culprit is likely the lilly pilly beetle (Paropsides calypso). These bright green beetles are similar in appearance to ladybirds and can be dealt with using neem oil or white oil.

Myrtle rust is a fungal disease caused by the pathogenic fungus Austropuccinia psidii. It is an invasive species that can severely impact various plants in the Myrtaceae family, including lilly pillies. If you spot any signs of this disease, promptly remove the affected leaves and apply fungicide for plants to the rest of the plant.

Seasonal care

Spring

Spring is the perfect time to give your lilly pillies a nutrient boost. Fertilise them with a high-quality, slow-release fertiliser to encourage vigorous growth and lush foliage. Additionally, side-dress the plants with composted manure before new growth emerges to provide them with an extra nutritional kick, allowing them to reach their full potential.

Summer

With the arrival of summer and the intensifying heat, watering becomes paramount. Your lilly pillies will need adequate drainage and reliable water supply, especially if they are grown in pots. For potted plants, opt for potting mix and ensure they receive regular watering to prevent stress and potential susceptibility to diseases.

Mulching is also a good idea in summer. Apply a layer of organic sugar cane mulch, approximately 5 to 8cm thick to help retain moisture in the soil, deter weed growth, and regulate soil temperature. As the mulch breaks down over time, it will also enrich the soil structure, contributing to the overall health of your lilly pillies.

With the favourable growing conditions of summer, your lilly pillies may experience strong growth and require pruning to maintain their shape and density. Do not hesitate to prune heavily if needed, as lilly pillies are remarkably resilient and can handle such trimming. Ensure you water the plants well before and after pruning to reduce any stress. If you are growing a hedge or screen, regular tip pruning on the top and sides will encourage dense, bushy growth. Remember to do this while the plants are young, as waiting until they reach the desired height may lead to less successful results. For accuracy when shaping hedges, consider using a string line.

Autumn and winter

In autumn, as the cooler weather sets in, do another light pruning and apply another dose of fertiliser to replenish the nutrients in the soil.

Before winter arrives, check the mulch levels around your lilly pillies to retain soil heat as long as possible, helping them endure the colder months.

For larger varieties that grow into trees or shrubs, they generally maintain an attractive shape with minimal pruning, requiring only occasional tidying up every few years. While pruning can be performed at any time of the year, it's advisable to undertake heavy pruning in late winter.

Looking to propagate your lilly pilly plants?

Check out our guide to planting and propagating lilly pillies.