Best Autumn Crops for Polytunnels in Australia
Autumn is one of the most productive seasons inside a polytunnel. As the intense heat of summer fades and soil temperatures remain warm, conditions are ideal for not only extending the season of your summer crops, but also establishing your winter crops.
For many growers, autumn planting is what keeps their tunnel productive when outdoor gardens begin to slow down. The protected environment inside a polytunnel allows many crops to keep growing long after colder nights and unpredictable weather begin to affect outdoor gardens. Choosing the right crops at this time of year allows you to take full advantage of the protected environment inside a polytunnel.
In this article, we explore some of the best autumn crops to grow in a polytunnel in Australia.
What are the best crops to grow in a polytunnel in Autumn
Tomatoes
Tomatoes are one of the most popular crops for tunnel growing. Planting or maintaining tomato crops in early autumn allows growers to extend the harvest window well beyond what is possible outdoors.
Benefits of growing tomatoes in a polytunnel:
Protection from rain which reduces fruit splitting and fungal diseases like blight
More consistent ripening due to stable temperatures
Easier pruning, trellising and harvesting in a protected environment
In many regions, tomatoes inside a tunnel can continue producing well into late autumn or early winter.
Capsicum and chillies
Capsicum and chilli plants also benefit from the warmer and more stable conditions inside a tunnel.
Autumn protection helps maintain fruit production as outdoor temperatures begin to drop.
Why capsicum and chillies perform well in tunnels:
Stable warmth encourages consistent flowering and fruit set.
Protection from wind prevents flowers dropping prematurely.
Better fruit colour and quality due to controlled growing conditions.
Many growers find capsicum and chilli crops can continue producing several weeks longer inside a tunnel compared with outdoor gardens.
CUCUMBERS
Cucumbers thrive in warm, protected environments, making tunnels ideal for extending their growing season.
When grown inside a polytunnel during autumn they benefit from:
Protection from cold winds that slow cucumber growth
Cleaner fruit as plants stay off wet soil and heavy rain
Longer productive vines before temperatures drop
Autumn tunnel growing often allows cucumbers to produce longer than outdoor plants.
Basil
Basil is highly sensitive to cold conditions, which makes autumn protection especially valuable.
Inside a polytunnel, basil can continue growing while outdoor plants often decline quickly once temperatures drop.
Benefits of growing basil in a tunnel include:
Protection from cold snaps that quickly damage basil outdoors
Stronger leaf growth due to consistent warmth
Reduced leaf spotting from rain and wind exposure
This makes basil an excellent companion crop alongside tomatoes and capsicum inside a tunnel.
Asian Greens
Asian greens are among the fastest‑growing crops available to tunnel growers.
Varieties such as bok choy, tatsoi and mizuna grow rapidly in autumn conditions and can often be harvested within weeks of planting.
These crops are particularly popular with market gardeners due to their:
Rapid turnover
Strong flavour
High productivity per square metre
They are also well suited to succession planting for continuous harvests.
Lettuce Varieties
Growing lettuce and salad green varieties in your polytunnel is a great way to cut-down your grocery bill and keep the growing going into the Autumn months. Mix it up with grow-and-pick varieties, Cos lettuce and more.
Many growers find lettuce grown in cooler conditions has superior flavour and texture compared with summer crops, which can often become bitter in extreme heat.
Autumn lettuce varieties typically grow steadily and produce tender, high‑quality leaves. Keep a steady supply growing, without taking up too much growing space, with our hydroponic GROW Towers – you can grow up to 42 plants in just 1 meter squared.
Spring Onions
Spring onions are a simple and reliable crop for autumn planting.
They establish quickly and require minimal maintenance while providing steady harvests throughout the cooler months.
Benefits include:
Reliable germination in protected soil conditions
Upright growth that makes harvesting quick and easy
Ability to harvest young or mature depending on preference
They are also an excellent crop for filling small gaps between other plants.
Radish
Radishes are one of the fastest crops you can grow in a polytunnel.
Many varieties can be ready to harvest in as little as three to four weeks.
Why radishes are ideal for autumn tunnels:
Extremely fast harvest, often ready within 25–30 days
Crisp root development in loose protected soil
Excellent for quick succession crops between larger plantings
Their quick growth makes them perfect for maintaining constant productivity inside the tunnel.
Carrots
Carrots grow particularly well in the protected soil conditions of a tunnel.
Autumn plantings benefit from cooler temperatures while avoiding heavy rain that can compact soil in outdoor beds.
Advantages of growing carrots in tunnels include:
Straighter root development in protected, loose soil
Reduced cracking caused by sudden rainfall changes
Consistent soil moisture for even growth
With the right spacing and soil preparation, carrots can provide excellent yields through winter.
Beetroot
Beetroot is another dependable autumn crop that performs well inside tunnels.
Cooler conditions often improve flavour while the protected environment helps maintain steady growth.
Growers appreciate beetroot because it offers:
Reliable germination during cooler autumn conditions.
Dual harvest from both tender leaves and roots.
Strong root development in protected soil beds.
Ready to
Get Growing?
Download our free guide to growing in a polytunnel today
Why Grow Autumn Crops in a Polytunnel?
A GROW Tunnel provides a protected growing environment that allows crops to establish quickly and continue producing long after outdoor gardens begin to slow.
Growing autumn crops inside a tunnel helps:
Protect plants from heavy rain
Reduce wind damage
Buffer early frost conditions
Extend harvests well into winter
By maintaining a more stable growing environment, tunnels allow growers to produce food more consistently throughout the year.
Protected cropping systems like polytunnels are increasingly used by both backyard gardeners and commercial growers because they improve yields and reduce crop losses from unpredictable weather.
Tips for Successful Autumn Planting
To get the most from your autumn crops:
Plant early in the season while soil temperatures remain warm
Use succession planting to maintain steady harvests
Monitor ventilation to prevent excess humidity
Maintain consistent soil moisture
These simple practices help ensure your tunnel remains productive through the cooler months.
Final Thoughts
Autumn is one of the best times of year to plant inside a polytunnel.
With the right crop selection and early planting, your tunnel can continue producing fresh food long after outdoor gardens begin to slow down.
Whether you're growing for your household or supplying a local market, autumn planting helps maximise the productivity of your tunnel and extend your harvest season.
And when conditions outside become unpredictable, the protection of a polytunnel helps ensure your growing efforts continue to pay off.
Thinking about growing in a polytunnel?
A GROW Tunnel makes it easier to produce consistent harvests across the seasons. Explore the range to see how protected growing can transform your garden or market garden.
