Sweet potatoes, with their rich flavour and versatility, are a favourite in many Australian homes and vege gardens.
Whether you’re starting with cuttings or using slips, understanding the right conditions and care requirements can make all the difference.
This year, I plan to grow sweet potatoes using slips and a styrofoam box placed in the sunniest corner of my garden (I’ll report back on how this goes).
This guide offers a step-by-step approach to successfully growing and harvesting sweet potatoes in Australia.
When to plant sweet potato in Australia
Sweet potatoes need to be planted in spring because they’re a warm-season crop.
Plus, you need to get them in fairly early because they will take around 5 months to grow before you can harvest the tubers.
How to plant sweet potato
First, you need to choose a sunny spot in the garden. Sweet potatoes need at least 6 to 8 hours of sunlight daily.
The soil should be friable and free-draining. These plants will not grow in soggy soils as the tubers will rot. You also want to incorporate lots of organic matter into the soil.
This will not only feed the growing plants but will also help to improve the structure of the soil and increase drainage.
Your sweet potato plants should also be protected from strong winds and can only be planted after all danger of frost has passed.
There are numerous ways that you can grow sweet potatoes. You can purchase established seedlings from your local nursery or garden centre. These will give you a head start.
Alternatively, sweet potatoes can also be grown from cuttings or from slips. A slip is a sprout that has grown from a tuber.
You can sprout your own slips but try to use organic sweet potatoes or ones that have been grown by a neighbour or friend.
How to grow sweet potatoes from cuttings
If you have a friend who is already growing sweet potatoes, you can ask them for a few cuttings. These should be soft-tip cuttings.
All you have to do with these is plant them into the prepared soil around 5 to 7 cm deep. Space individual cuttings around 40 to 50 cm apart.
If kept watered, these cuttings should easily produce roots and the new plants will start to grow. Bear in mind that sweet potatoes grow as a vine, so you’ll need to give them space to spread.
How to grow sweet potatoes using slips
This is a handy way to grow sweet potatoes if you aren’t able to obtain any fresh cutting.
While you can easily purchase sprouted slips, it’s not that difficult to create your own. You want to start this process around 8 to 12 weeks before you want to plant them outside.
This means that you’ll have to find a warm and bright spot inside to give the tubers a chance to sprout. To ensure maximum success, you might want to invest in a heat mat and even a grow light.
As an alternative, consider placing your box of tubers on top of the fridge or your hot water service if this is located inside.
Get a styrofoam box, like those available at greengrocers, and fill this with sand. Half bury the sweet potatoes on their sides in the sand and keep the sand moist.
In a few weeks, you should start to see some sprouts appearing from the visible parts of the tubers. Once the sprouts are around 15 cm long, you can remove the tubers from the sand.
If roots have formed well on the slips and you are able to remove these gently from the sand, your sweet potato slips are now ready to be planted in the garden. Remember that the slips are the new growth that has sprouted from the tuber.
If there are not many roots or you’ve broken them when removing the tubers from the sand, you’ll need to root your slips in water.
How to root sweet potato slips in water
Carefully remove the sprouts or slips from the sweet potato. You can either gently twist them off or cut them with a sharp knife. Remove some of the lower leaves of each slip.
Fill a glass or jar with clean water. Place the slip into the water so that the bottom is submerged. Don’t be surprised if you start to see roots developing quite quickly. This will usually only take 1 to 2 days.
However, you want to wait until the roots are well formed and at least 15 cm long before taking the slips out of the water and planting them in the soil.
Make sure you keep the water topped up and replace it every couple of days to keep it nice and fresh. You might find that some of the slips will wilt or even rot. These should be discarded.
Once the slips have produced a good root system, you can plant them in the garden in the same way that you would plant cuttings.
How to care for sweet potatoes
Sweet potatoes will grow easily and don’t require a lot of extra care. All you have to do is keep them well-watered and make sure that they receive plenty of sunlight.
The plants don’t require any additional fertiliser in order to produce their tubers.
How long do sweet potatoes take to grow?
It can take around 5 months between planting your sweet potatoes and being able to harvest the tubers. This means that you need to give them plenty of time to grow while the weather is warm.
When to harvest sweet potatoes
Once the leaves of your sweet potato plants have turned yellow, it’s time to harvest the tubers. This will usually be in early winter here in Australia.
How to harvest sweet potatoes
Harvesting your sweet potatoes couldn’t be easier. All you have to do is gently dig up the tubers using a small trowel or garden fork.
It’s a good idea to cure the harvested tubers in the sun for a few days before storing them in a dark spot inside.
Sweet potato pests and diseases
Garden-grown sweet potatoes don’t face as many pests and diseases as those grown commercially. However, your sweet potatoes can be attacked by sweet potato weevils if grown in the ground.
Unfortunately, you won’t know you have this problem until it comes time to harvest the tubers and you find them riddled with holes and unusable. There is no treatment for this pest.
Companion plants for sweet potato
Some good companion plants for sweet potatoes include:
- Dill
- Thyme
- Beetroot
- Beans
- Cucumbers
How to grow sweet potatoes in water
A popular trend these days is to grow all sorts of different plants in water and this can work with sweet potatoes.
While this method will not produce any tubers, you will end up with a lovely indoor plant that you can watch grow.
You can use any type of tuber for this, even those purchased from a supermarket. Here’s what to do:
- Fill a glass or jar with water
- Submerge the bottom half of a sweet potato tuber in the water
- Insert a couple of toothpicks into the sides of the tuber to hold it in place
- Place the glass or jar in a bright spot like a sunny windowsill
- Change the water every couple of days
Within a few days, you should see the tuber grow both a sprouting tip and roots in the water.
FAQ
Do sweet potatoes need a trellis?
Sweet potatoes grow as a vine and will scramble along the ground. However, if you have limited space, you can easily train the vine to grow up a trellis instead.
How long can you keep sweet potatoes in the ground?
It’s fine to leave sweet potatoes in the ground for a few weeks once they’re ready to harvest. However, you want to dig them up before there’s any danger of frost.
can I keep the sweet Potatoe vine alive in the winter