🌸 Rustic Harvest Dahlia Growing Guide
Everything you need to know to grow beautiful dahlias from tubers
Australian-grown dahlia tubers | From our flower farm to your garden
Welcome to the Rustic Harvest Dahlia Growing Guide 🌸
Growing dahlias from tubers is incredibly rewarding. From planting a small dormant tuber in spring to harvesting armfuls of flowers throughout summer and autumn, dahlias can become one of the most rewarding plants in your garden.
Whether you're growing your first dahlia or adding to an established cut flower garden, this guide covers everything you need to know about growing dahlias in Australia, including when to plant dahlia tubers, how to plant them, watering, feeding, staking, harvesting and storing your tubers.
Australian-grown dahlia tubers | From our South Australian flower farm to your garden
🌱 How to Grow Dahlia Tubers
Dahlia tubers are dormant storage organs that contain everything the plant needs to begin its new season of growth.
Once planted into warm soil and given the right conditions, an eye on the tuber will begin to produce a new shoot. That shoot develops into a leafy plant, followed by the beautiful flowers dahlias are known for.
The key to successfully growing dahlias is providing:
- Plenty of sunlight
- Fertile, well-draining soil
- Consistent moisture once actively growing
- Good airflow
- Support for taller varieties
- Regular harvesting and deadheading
🌸 Receiving Your Dahlia Tubers
Your Rustic Harvest dahlia tubers have been carefully lifted, divided, inspected and packed by hand.
When your tubers arrive:
- Carefully remove them from their packaging.
- Check that the tuber is firm and healthy.
- Don't be concerned if a tuber looks slightly dry or wrinkled.
- If you aren't ready to plant immediately, store your tubers somewhere cool, dark and dry.
Do I need to soak dahlia tubers before planting?
We recommend planting your dahlia tubers directly into the soil rather than soaking them first.
Keeping dormant tubers excessively wet can increase the risk of rot. Once planted into suitable soil and provided with the right conditions, the tuber will naturally begin to take up moisture.
☀️ Where to Plant Dahlias
Dahlias grow best in a sunny position with fertile, well-draining soil.
Choose a location that receives approximately 6–8 hours of sunlight per day.
The ideal dahlia growing location has:
- Full sun
- Rich, fertile soil
- Good drainage
- Good airflow
- Protection from strong winds where possible
Avoid areas where water sits after rainfall or irrigation.
As dahlia plants become larger, good airflow becomes increasingly important. Avoid overcrowding your plants and allow enough room for mature plants to grow.
🌿 Preparing Soil for Dahlia Tubers
Healthy soil is the foundation of healthy dahlia plants.
Before planting your tubers, prepare the soil by loosening it and incorporating plenty of organic matter such as compost or well-aged manure.
How to prepare soil for dahlias
- Loosen the soil to approximately 20–30 cm deep.
- Remove weeds, large stones and debris.
- Add compost or well-aged manure.
- Incorporate a suitable fertiliser if required.
- Make sure excess water can drain freely.
Dahlias are hungry plants and appreciate fertile soil throughout the growing season.
📅 When to Plant Dahlia Tubers in Australia
The best time to plant dahlia tubers depends on your location and local climate.
As a general guide:
Warmer Australian areas: August–September
Cooler Australian areas: September–October
Frost-prone areas: Wait until the risk of significant frost has passed.
Dahlias are warm-season plants and don't perform well when planted into cold, wet soil.
Waiting until the soil has warmed in spring can help your tubers establish successfully.
When to plant dahlias in South Australia
Here at Rustic Harvest, we grow our dahlias in South Australia, where planting times are influenced by our local temperatures, soil conditions and frost risk.
Your ideal planting time may vary depending on your exact location, so use these dates as a guide rather than a strict rule.
🌱 How to Plant Dahlia Tubers
Planting dahlia tubers is simple once the soil is warm and prepared.
1. Dig a hole
Dig approximately 10–15 cm deep.
2. Position the tuber
Place the tuber horizontally in the hole with the eye facing upwards.
The eye is the small growing point on the crown where the new shoot will emerge.
3. Cover with soil
Cover the tuber with soil.
Avoid planting significantly deeper than recommended, particularly in heavy or poorly draining soil.
4. Water lightly
Give the soil a light watering after planting if the soil is very dry.
Avoid keeping dormant tubers constantly wet. Once shoots emerge and the plant begins actively growing, gradually increase watering.
📏 How Far Apart Should Dahlias Be Planted?
Dahlia spacing depends on the variety and the size of the mature plant.
As a general guide:
Small dahlias: 30–45 cm apart
Medium dahlias: 45–60 cm apart
Large or dinnerplate dahlias: 60 cm or more apart
If you're growing dahlias as cut flowers, remember that plants can become surprisingly large during the growing season.
Adequate spacing helps with airflow, access for harvesting and overall plant health.
💧 How Often Should You Water Dahlias?
Watering requirements change throughout the season.
Before shoots appear
Dahlia tubers don't need large amounts of water while dormant.
Water sparingly and avoid keeping the soil saturated.
Once dahlias are actively growing
Once shoots emerge and plants begin developing leaves and stems, they need regular moisture.
Established dahlias may require watering 1–3 times per week, depending on rainfall, soil type and temperature.
During hot Australian weather, plants may need additional water.
The aim is to keep the soil consistently moist while allowing excess water to drain away.
Should you water dahlia leaves?
Whenever possible, water around the base of the plant rather than regularly wetting the foliage.
Good airflow and keeping foliage relatively dry can help reduce the risk of fungal problems.
☀️ Watering During Heat Waves
During periods of extreme heat, your dahlias will need some extra attention.
If a very hot day is forecast, water your dahlias deeply the evening before. This allows the soil to become thoroughly hydrated before the heat of the following day.
During prolonged heat waves, check your plants regularly and water deeply as needed. Mulching around the plants can also help retain moisture and keep the soil cooler.
Avoid shallow watering, as this can encourage roots to remain close to the soil surface where they are more vulnerable to heat and drying out.
🌿 How to Support Dahlia Plants
Many dahlia varieties grow tall and produce large, heavy flowers.
Supporting your plants early is much easier than trying to rescue a mature plant that has fallen over.
You can use:
- Stakes
- Multiple stakes for large plants
- String or garden ties
- Other suitable plant support systems
Install supports early in the growing season and tie plants as they grow.
🌸 Should You Pinch Dahlias?
Pinching the growing tip of a young dahlia plant can encourage branching and produce more flowering stems.
Once the plant has established and has at least 2-3 sets of leaves, you can pinch out the central growing tip above a set of leaves.
This encourages the plant to produce additional side shoots.
For cut flower production, branching can be particularly beneficial because it can result in more usable flowering stems.
✂️ How to Harvest Dahlia Flowers
One of the best things about growing dahlias is being able to bring armfuls of flowers inside.
And regular harvesting encourages the plant to continue producing flowers.
For cut flowers, harvest in the early morning when plants are well hydrated.
Choose blooms that are almost fully open as dahlias tend not to continue opening once harvested.
Cut the stem back to a leaf junction or branching point to encourage further flowering.
The more regularly you harvest, the more flowers your plant can produce throughout the season.
🌸 How to Deadhead Dahlias
Regular deadheading encourages your dahlia plant to continue producing flowers.
Remove spent flowers before the plant puts energy into producing seeds.
When deadheading, don't simply remove the flower head. Follow the stem down to the next set of leaves or branching point and cut there.
This keeps the plant tidy while encouraging new flowering stems.
🌱 Feeding Dahlias
Dahlias are hungry plants, particularly once they are actively growing and producing flowers.
Starting with fertile soil and plenty of organic matter provides a strong foundation.
During the growing season, a suitable fertiliser can be applied according to the manufacturer's directions.
🐛 Common Dahlia Pests and Problems
Aphids on Dahlias
Aphids can appear on fresh new growth, flower buds and young stems.
Check your plants regularly and deal with infestations early.
Depending on the severity, options include:
- Removing aphids by hand
- Washing them from the plant with water
- Encouraging beneficial insects
- Using an appropriate treatment where necessary
🐌 Slugs and Snails
Slugs and snails can cause significant damage to young dahlia shoots.
Check plants regularly, particularly after rain and during damp conditions.
Hand removal, physical barriers and suitable slug and snail controls can help protect young plants.
🍃 Powdery Mildew on Dahlias
Powdery mildew appears as a white, powdery coating on the leaves.
Good airflow is one of the best ways to reduce the risk.
To encourage healthy plants:
- Give plants adequate spacing
- Avoid overcrowding
- Remove badly affected leaves
- Water the soil rather than regularly wetting foliage
- Keep the growing area clean
🌸 How to Get More Flowers from Your Dahlias
If your goal is armfuls of dahlia flowers, focus on the basics:
☀️ Plenty of sunlight
🌱 Fertile, well-draining soil
💧 Consistent watering once actively growing
🌿 Good plant support
✂️ Regular harvesting
🌸 Regular deadheading
The more you harvest and care for your plants throughout the season, the more flowers you can enjoy.
❄️ What to Do with Dahlia Tubers at the End of the Season
In colder parts of Australia, dahlias may be damaged by frost at the end of the growing season.
Once your plants have finished flowering and the foliage has been affected by frost or naturally begun to die back, you can prepare to lift your tubers.
In areas with mild winters, dahlias can sometimes be left in the ground, provided the soil drains well and winter conditions are suitable.
🌱 How to Lift Dahlia Tubers
If you choose to lift your dahlias at the end of the growing season:
1. Cut the plant back
Once the plant has finished for the season, cut the stems back.
2. Lift the clump
Carefully loosen the soil around the plant using a fork or spade.
Gently lift the entire clump from the ground, taking care not to damage the tubers.
3. Allow the clump to dry
Allow excess moisture to dry from the clump before storing.
4. Divide your tubers
Large clumps can be divided into individual tubers when dormant.
Each viable division needs a tuber, a piece of crown and a healthy eye.
5. Store your tubers
Store dormant dahlia tubers somewhere cool, dark and protected from excessive moisture.
Check stored tubers periodically throughout winter and remove any that show signs of rot.
🌸 Growing Dahlias for Cut Flowers
Dahlias are one of our favourite flowers to grow for cutting.
If you're growing your dahlias specifically for cut flowers, focus on:
- Full sun
- Fertile soil
- Good plant spacing
- Regular feeding
- Strong support
- Pinching young plants
- Regular harvesting
- Regular deadheading
Don't be afraid to cut your flowers!
Regular harvesting encourages the plant to produce more flowering stems throughout the season.
🌱 Frequently Asked Questions About Growing Dahlias
Can you grow dahlias from tubers?
Yes! Growing dahlias from tubers is one of the easiest ways to establish new dahlia plants. A healthy tuber with a viable eye can produce an entirely new plant.
How deep should dahlia tubers be planted?
As a general guide, plant dahlia tubers approximately 10–15 cm deep, depending on your soil and conditions.
Do dahlias need full sun?
Dahlias perform best in full sun and generally benefit from around 6–8 hours of sunlight per day.
When should I plant dahlia tubers in Australia?
Planting time varies with climate. Many Australian gardeners plant from August through October, with cooler and frost-prone areas generally planting later.
How long do dahlia tubers take to sprout?
Sprouting time varies depending on soil temperature, moisture, variety and growing conditions. Don't be concerned if your tubers take some time to emerge.
How long do dahlias flower?
Once established, dahlias can provide flowers for an extended period through the warmer months, particularly when flowers are harvested and spent blooms are removed regularly.
🌱 Ready to Grow Your Own Dahlias?
Explore our collection of Australian-grown dahlia tubers and find your next favourites for the garden.
Happy growing! 🌸
🌸 A Note From Rustic Harvest
Growing dahlias is a journey, and every season teaches you something new.
Some varieties will become instant favourites. Some will surprise you. And occasionally, a tiny little tuber will turn into the biggest and most spectacular plant in your garden.
We hope your Rustic Harvest dahlia tubers bring you plenty of flowers, colour and joy.
We'd love to see what you're growing!
Tag us on Instagram @rustic_harvest
and share your blooms with us. 🌸
