A Gardener's Guide to Subtropical Climates
Understanding subtropical gardens and what makes them thrive
When one thinks of the subtropics, the mind is immediately drawn to images of lush green foliage and vibrantly coloured flowers. Plant hardiness zone five is where you’ll find this type of scenery. This zone covers the eastern Australian coastline; from Coffs Harbour, through to Brisbane, as far north as Mackay and midway up Queensland’s coast. In Western Australia, the subtropical zone roughly follows the coast north of Exmouth to Broome, and inland to Halls Creek.
If you live in this zone, you’ll know that the subtropical climate is essentially mild, with plenty of sunshine, warm growing conditions and good summer rains. There is high humidity from November through to March, frosts are rare and temperatures generally don’t dip below 10°C. Think warm and humid, with wet summers and an average January maximum temperature of no more than 30°C. It’s often good to think of just two seasons; a wet one that covers summer and autumn, and a dry one through winter and spring.
By following this guide, you will discover how to kick-off your subtropical garden. Achieve this gardening zone’s defining characteristics of bold foliage and vibrant colours by knowing what and when to plant, along with how to make the theme work for you.
If you live in this zone, you’ll know that the subtropical climate is essentially mild, with plenty of sunshine, warm growing conditions and good summer rains. There is high humidity from November through to March, frosts are rare and temperatures generally don’t dip below 10°C. Think warm and humid, with wet summers and an average January maximum temperature of no more than 30°C. It’s often good to think of just two seasons; a wet one that covers summer and autumn, and a dry one through winter and spring.
By following this guide, you will discover how to kick-off your subtropical garden. Achieve this gardening zone’s defining characteristics of bold foliage and vibrant colours by knowing what and when to plant, along with how to make the theme work for you.
Go native
There are plenty of great native plants to choose from, which will ensure your subtropical garden looks the part. Palms with slender trunks, such as Archontophoenix, are distinctly subtropical, as are large fig trees (Ficus), hoop pines (Araucaria cunninghamii), cycads (Tracheophyta), and staghorn ferns (Platycerium).
Other winners include pink hibiscus (Hibiscus splendens), blue flax-lily (Dianella caerulea), kangaroo vine (Cissus Antarctica) and native frangipani (Hymenosporum flavum). Among tall foliage plants is gymea lily (Doryanthes excelsa), which is native to northern NSW, while blueberry ash (Elaeocarpus reticulatus) is an evergreen native tree naturally occurring in eastern Australian forests.
Bulbs can also be brilliant in a subtropical garden, especially the Brisbane lily (Proiphys cunninghamii), with its large, deeply veined leaves and fragrant white flowers.
There are plenty of great native plants to choose from, which will ensure your subtropical garden looks the part. Palms with slender trunks, such as Archontophoenix, are distinctly subtropical, as are large fig trees (Ficus), hoop pines (Araucaria cunninghamii), cycads (Tracheophyta), and staghorn ferns (Platycerium).
Other winners include pink hibiscus (Hibiscus splendens), blue flax-lily (Dianella caerulea), kangaroo vine (Cissus Antarctica) and native frangipani (Hymenosporum flavum). Among tall foliage plants is gymea lily (Doryanthes excelsa), which is native to northern NSW, while blueberry ash (Elaeocarpus reticulatus) is an evergreen native tree naturally occurring in eastern Australian forests.
Bulbs can also be brilliant in a subtropical garden, especially the Brisbane lily (Proiphys cunninghamii), with its large, deeply veined leaves and fragrant white flowers.
Plant at the right time
Summer brings rain, making this an ideal time to plant and propagate while the ground is warm and moist. As summer turns to autumn, the subtropical garden will be looking its best, with temperatures cooling a little, the light softer and a haze of humidity. Plants will have grown over summer, and by this time, they’ll be looking lush and luxuriant.
Summer brings rain, making this an ideal time to plant and propagate while the ground is warm and moist. As summer turns to autumn, the subtropical garden will be looking its best, with temperatures cooling a little, the light softer and a haze of humidity. Plants will have grown over summer, and by this time, they’ll be looking lush and luxuriant.
Support healthy soil conditions
Although subtropical gardens get twice as much summer rainfall than their southern cousins, the rain doesn’t always fall reliably. That’s why it’s important to really improve the soil in a subtropical garden. Because gardens are fed by rain, adding lots of compost means the soil will drink up all of the significant rainfall and stay nice and moist.
Although subtropical gardens get twice as much summer rainfall than their southern cousins, the rain doesn’t always fall reliably. That’s why it’s important to really improve the soil in a subtropical garden. Because gardens are fed by rain, adding lots of compost means the soil will drink up all of the significant rainfall and stay nice and moist.
Choose an appropriate colour palette
Bright colours and glossy greens (rather than the woody grey-greens commonly found in drier parts of the country), along with vibrant purples and reds, are all key colour palettes of a subtropical garden.
Go for a natural look, favouring dense plantings in odd-number groups, contrasting foliage and clumping colour. Look out for mass-flowering trees and for shrubs with a limited number of large or brightly-coloured flowers. Pay attention to the architectural or sculptural forms in each layer, adding vertical palms, and plants with large or dissected leaves, pinnate fronds with strong textural qualities, tufted borders or bold flower shapes to create this natural look.
Bright colours and glossy greens (rather than the woody grey-greens commonly found in drier parts of the country), along with vibrant purples and reds, are all key colour palettes of a subtropical garden.
Go for a natural look, favouring dense plantings in odd-number groups, contrasting foliage and clumping colour. Look out for mass-flowering trees and for shrubs with a limited number of large or brightly-coloured flowers. Pay attention to the architectural or sculptural forms in each layer, adding vertical palms, and plants with large or dissected leaves, pinnate fronds with strong textural qualities, tufted borders or bold flower shapes to create this natural look.
Continue the theme
Layers of plantings and enclosed zones dominate in the subtropical garden and can be accentuated with walls covered in rambling plants and vines. High rainfall means plants in the subtropical garden will tend to compete for sunshine – rather than for water and nutrients – and this can create strong vertical growth. Evergreen trees with large foliage and attractive flowers or fruit offer structure and shade.
Beneath the canopy of trees, you’ll find shade-loving plants with dark green leaves, colourful foliage and bright flowers or fruits. Shade-tolerant perennials dominate the ground layer, along with rich organic mulches. A water feature will add another dimension to the layers and help create humidity.
While mass plantings and lush layers are a must, it’s important not to get too carried away. Start with a plan and stick to it so that your layers don’t end up competing. Avoid straight lines for pathways and opt for randomly shaped garden beds in a variety of sizes to keep that all-important free-flowing look.
With the warm weather and beautiful greenery, you may also want to invest in extra backyard additions. Hang a hammock, invest in whicker outdoor seating, or even an outdoor bath tub to enhance the resort-style feel a subtropical garden can embody.
Layers of plantings and enclosed zones dominate in the subtropical garden and can be accentuated with walls covered in rambling plants and vines. High rainfall means plants in the subtropical garden will tend to compete for sunshine – rather than for water and nutrients – and this can create strong vertical growth. Evergreen trees with large foliage and attractive flowers or fruit offer structure and shade.
Beneath the canopy of trees, you’ll find shade-loving plants with dark green leaves, colourful foliage and bright flowers or fruits. Shade-tolerant perennials dominate the ground layer, along with rich organic mulches. A water feature will add another dimension to the layers and help create humidity.
While mass plantings and lush layers are a must, it’s important not to get too carried away. Start with a plan and stick to it so that your layers don’t end up competing. Avoid straight lines for pathways and opt for randomly shaped garden beds in a variety of sizes to keep that all-important free-flowing look.
With the warm weather and beautiful greenery, you may also want to invest in extra backyard additions. Hang a hammock, invest in whicker outdoor seating, or even an outdoor bath tub to enhance the resort-style feel a subtropical garden can embody.
Some extras to try
Sweet potato (Ipomoea batatas), cassava (Manihot esculenta), Queensland arrowroot (Canna edulis), yacón (Smallanthus sonchifolius) and jícama (Pachyrhizus erosus) all grow well in the subtropics, as does the majestic avocado (Persea americana), which can grow up to 12 metres tall, but is usually best kept pruned to a height of no more than 5 metres.
TELL US
Do you live in a subtropical climate? What have you planted in your garden that thrives? Let us know in the Comments.
MORE
A Gardener’s Guide to Coastal Climates
How to Bring Your Subtropical Garden to Life
10 Tips for Creating a Formal Garden in the Subtropics
Sweet potato (Ipomoea batatas), cassava (Manihot esculenta), Queensland arrowroot (Canna edulis), yacón (Smallanthus sonchifolius) and jícama (Pachyrhizus erosus) all grow well in the subtropics, as does the majestic avocado (Persea americana), which can grow up to 12 metres tall, but is usually best kept pruned to a height of no more than 5 metres.
TELL US
Do you live in a subtropical climate? What have you planted in your garden that thrives? Let us know in the Comments.
MORE
A Gardener’s Guide to Coastal Climates
How to Bring Your Subtropical Garden to Life
10 Tips for Creating a Formal Garden in the Subtropics
Because the growing season in the subtropics is long – often continuous – plants can reach maturity faster than those in temperate zones. While this means a subtropical garden can look mature in as little as three years, it also means that garden maintenance can be a bit of a challenge. With this in mind, it’s always advisable to focus on slow-growing plants as the backbone of your subtropical garden.