Banksia serrata | Growing + Care Guide Australia

What is Banksia serrata? 

Banksia form part of the Proteaceae family and grow natively across southern parts of Australia. The Banksia serrata species can be found growing all along the east coast of Australia, from Queensland to Tasmania. 

This soft-wooded evergreen is considered a small to medium-sized tree, offering a medium growth rate. However, over its lifespan it can grow anywhere between 3 to 15 metres.

Banksia serrata cultivar, such as the Banksia ‘Pygmy Possum’ is an excellent option for those looking for a small growing tree. Banksia serrata is best known for its saw-like, serrated leaves and eye-catching green-yellow flowers. 

Other common names include: 

• Old Man Banksia
• Saw Banksia
• Banksia ‘Pygmy Possum’

Why Should You Consider Growing Banksia serrata? 

The Banksia ‘Pygmy Possum’ has a lot of landscaping value, grown across many coastal landscapes and is even used for street-scaping. Not only is it exceptionally drought-tolerant, but it also requires very little maintenance once established. 

It’s an ideal option for flower gardens, coastal gardens and can even function as a reasonably reliable screening plant or wind-breaker. Plus, the banksia serrata’s sought-after pollen supports local honey production and will attract lots of butterflies, bees and nectar-seeking birds. 

How to Grow Banksia serrata

Serrata plants are straightforward to cultivate, and luckily, seeds are readily available if you live near naturally growing serrata plants. 

Propagation from seed is recommended, as it’s most comfortable and cost-effective. Even without any pre-treatment, your seeds will likely germinate anywhere between 3 to 4 weeks after sowing. 

Propagation from a cutting is possible, but not recommended from this cultivar. Cuttings are very slow to strike and mostly end up being unsuccessful. 

How to Propagate from Seed

Seed propagation is relatively straightforward, and you can source your seeds either from a licensed supplier or from an existing and healthy serrata plant. When collecting a seed pod, be sure to choose a large existing tree for maximum success. 

Seeds can be collected throughout the year. 

To propagate your serrata tree, you’ll need to:

• Place the seed cone into the oven at 120°C for about an hour. 
• Once the seed pod opens, remove individual seeds with a sterilized pair of tweezers. 
• Prepare your seeding mix by sterilizing it, as banksia are prone to fungal infection. A vermiculite seeding mix is recommended. 
• Sow your seeds directly into the soil and keep the soil moist. Do not let the soil dry out fully. 
• Transplant into a bigger pot or soil as soon as some small leaves appear.

Where to Grow Banksia serrata

Once you’ve propagated your seedling, it’s essential to choose the right spot for your serrata. While you can grow the serrata species in a pot, in the soil is preferred. 

The most crucial factor is to give your serrata the right soil, sun and temperature conditions for ideal growth. 

Soil

Ensuring the right soil is likely the most critical factor for Banksia growth. The serrata cultivar prefers sandy or loam soil with varying PH levels. The ground must be mostly-dry and well-draining. In general, try to avoid clay soils. 

Sun

Banksias enjoy plenty of sunshine so choose a spot in your garden which receives lots of sun. 

Temperature

The serrata cultivar is said to be frost-hardy. However, it grows best in sub-tropical warmer conditions.

How to Care for Banksia serrata

Once established, your Banksia serrata really won’t need much care beyond the occasional watering, fertilising and pruning. 

In general, with most Banksia species, less is more, and they deal quite well with a little bit of neglect. 

Watering Old Man Banksia

In the first two years of growth, it is recommended to water your Banksia regularly. You will want to keep the soil moist, but not water-logged as this will lead to disease.

After that, you can almost cut-back on watering completely, especially during seasons with heavy rainfall. 

How to Fertilise Banksia ‘Pygmy Possum’

Again, regular fertilisation is only required within the first two years. In those years you can fertilise yearly, after that you can cut back to every few years. Over-fertilisation can cause your serrata to wilt, so be sparing with your fertiliser. 

Pruning Your Saw Banksia

Pruning is mainly done to maintain size and shape. It’s crucial only to cut back new growth and avoid old growth. If you want to keep your serrata plant small, prune more frequently. Always ensure you use a sterilized blade or pruning saw to prune. 

Your Banksia serrata will flower from September through to February. If you wish, you can cut back dead flowers. However, this will only be for aesthetic reasons and won’t affect your plant.

Common Banksia serrata Problems 

At some point in your growth journey, you may ask yourself why your Banksia might be dying? While the Banksia serrata is relatively problem-free, there are three significant factors for which you’ll need to keep an eye out.

Why Are My Banksia Leaves Brown? 

The browning of leaves is usually due to root rot, a common problem for Banksia plants. Root rot is the result of over-watering or waterlogged roots. If not treated, root rot can be a significant killer.

Be sure to re-plant your Banksia if possible and cut back on watering significantly. 

Why Are My Banksia Leaves Yellow? 

Yellow leaves are a sign of phosphorous toxicity. Banksia species are susceptible to phosphorous, and it can be dangerous for your plant, especially as phosphorous poisoning may only show signs 12 months later.

Ensure you make use of a low phosphorous fertiliser and avoid over-feeding at all costs. 

Do Banksias Have Pest Problems? 

You’re not likely to get many pest issues with most cultivars of the Banksia species. However, caterpillars seem to be drawn to Banksia plants. You can safely avoid caterpillars with natural repellents like neem oil or coffee grounds.