Asparagus is easy to grow, but it’s not your typical green in the garden.
That’s because planting it also means cultivating your patience.
While we can’t teach you that, we can share the best ways to grow asparagus.
When to Plant Asparagus in Australia
The best time to plant asparagus crowns in Australia is between August and November, late winter through the end of spring.
This allows the crowns to establish themselves before the growing season begins in spring.
Meanwhile, spring is the best time for asparagus seeds or until frost has passed.
Where to Plant Asparagus in Australia
Plant your asparagus in a sunny, well-drained spot in your garden. Make sure the planting site gets at least 7 hours of direct sunlight daily.
Avoid areas that are low-lying, exposed to frost, or prone to erosion.
If you have an existing vegetable patch, basil and tomatoes are excellent companion plants for asparagus.
How Long Does Asparagus Take to Grow?
Asparagus plants grown from seeds can take between 2 to 8 weeks to develop into seedlings, which then take about 3 years to reach harvest.
Meanwhile, asparagus plants grown from crowns or cuttings can take 2 years to mature.
Soil Requirements to Grow Asparagus
Asparagus prefers a slightly alkaline, well-drained soil to grow in.
Test your soil before planting them, or you can mix the following materials for optimal asparagus growth:
- ⅔ soil
- ⅓ compost
- ⅓ cow manure
How to Grow Asparagus From Cuttings or Crowns
It’s most common to start asparagus from crowns, which are one-year-old plants containing the root system of an asparagus plant.
Soak the asparagus crowns
Soak your asparagus crowns in water for 15 to 30 minutes to moisten the roots before planting.
You can use a manure tea to soak your asparagus crowns for added nutrient support.
Prepare the asparagus bed
To plant asparagus optimally, you’ll need a properly spaced furrow – a long narrow trench that is about 20–30cm deep and 30–40cm apart.
Plant your crowns and cover them with soil
Place the asparagus crowns at the bottom of the trench and spread the roots out evenly.
Cover them with 5–8cm of soil and check that they aren’t touching each other..
As they grow and sturdy stalks start to emerge, cover them with more soil, about 8 and 10 cm at a time.
Tip: In cooler climates or during the winter season, you’ll need to dig deeper holes to allow warmth and insulate your crowns.
Water and fertilise your crowns
Keep the soil consistently moist, but not waterlogged, during the growing season.
Asparagus does not like dry conditions, especially when they are still establishing themselves.
The neat thing is asparagus benefits from high-nitrogen fertilisers. Use a balanced one in the early spring and again after the harvest season.
How to Grow Asparagus From Seed
While growing asparagus from seed can be more challenging than growing from crowns, this method prevents asparagus plants from experiencing trauma during re-planting.
Prepare your asparagus seeds
Asparagus seeds can be started indoors to get a head start on the growing season. This is typically done in late winter or early spring.
Use a seed-raising mix in trays or pots and plant the seeds about 1–2 cm deep. Keep the soil moist and in a warm, sunny location.
Tip: During the growing phase, asparagus seeds grow optimally at a soil temperature between 16°C to 30°C during the day and 15°C to 21°C at night.
Set up your outdoor asparagus bed
Since asparagus seeds take anywhere from 2 to 8 weeks to germinate, you can start setting up your outdoor garden bed for them.
Choose a space where you have full access to sunlight and ensure proper drainage.
Remove weeds from your asparagus bed to allow optimal growth for your asparagus plants.
Next, prepare your soil and make sure you add well-composted manure to boost your asparagus growth.
You also want to make sure that the soil is moist (not wet) before transplanting your asparagus seeds.
This is better than watering your asparagus seeds after transplanting them.
Transplant the asparagus seedlings
Once the seedlings are about 10–15 cm tall and the danger of frost has passed, they can be transplanted outdoors. This is usually done in late spring or early summer in Australia.
Dig trenches in your garden bed about 20 cm deep and 30–40 cm apart. Place the seedlings at the bottom of the trench, spacing them about 40–50 cm apart.
Just like the crowns, cover your asparagus seedlings with 5–8cm of soil and water well.
Note: Unlike crowns, asparagus grown from seed will not be ready to harvest for at least 3–4 years. This allows the plants to develop a strong root system.
Mulching your asparagus bed
Mulching prevents weeds from growing near your asparagus plant.
You can cover your asparagus bed with 7–10 cm of straw to keep it warm during winter, between June and August.
Growing Asparagus in Pots
You can also plant asparagus indoors using pots or containers.
This method is ideal for those with limited outdoor space.
However, asparagus grows best outdoors and it’s recommended that you transfer it to a soil bed after 12 to 14 weeks.
Follow these steps to get started:
Prepare your potting mixture
Fill your pot with a standard soil-less potting mixture with the following components:
- 40% milled peat moss
- 30% loam or potting soil
- 15% vermiculite
- 15% perlite
- A bit of sand
You can also try readily available soil-less potting mixes in the market for convenience.
Remember: Be sure to choose a pot or container with a hole at the bottom to allow enough room for a large root system.
Plant your asparagus seeds 0.5 cm deep in the soil-less potting mix, then lightly cover.
Important: Asparagus seeds need warmth.
You can place your pot in a warm place, like the top of the fridge, until they sprout.
Be sure to put a covering on the pot to help retain moisture.
Once seedlings start to sprout, place them in front of your window for sunlight.
For asparagus crowns, you can follow the same process mentioned above.
Transfer your seedlings
Once the seedlings have emerged and are sturdy enough for transferring, you can follow the same steps in planting asparagus directly onto the ground.
Tips: Plant your asparagus seedlings outdoors when temperatures are consistently above 15°C. Also, don’t bury the seedlings too deeply.
Watering Your Asparagus
Water newly planted asparagus plants early in the morning once per week.
For established asparagus plants, water them about 20–30 cm deep once per week.
If your asparagus is planted in sandy soil, water it more than once per week.
Always allow the soil to dry out between waterings.
Fertilising Asparagus Plants
If your asparagus seedlings have emerged and are at least 5 cm tall, you can begin fertilising them once per week with 20-20-20 water-soluble fertilisers.
Carefully follow the mixing instructions on the product label.
Tips Before Harvesting Asparagus
Once your asparagus matures, you can enjoy a steady harvest for more than a decade.
Here are a few tips to take note of before harvest season begins:
No harvest on your first spring
Do not harvest spears on your first spring (a year after planting).
This is to allow them to develop into ferns and establish crown strength beneath the soil.
Wait until spears mature on your second spring
After the second year of planting, you can begin to harvest asparagus spears when they reach 15–20 cm in length as long as they are healthy during the previous growing season.
Allow spears to become ferns
Pick your asparagus only for 2 weeks during your first year of harvest (not planting) to allow the spears to become ferns.
Note: Some farming enthusiasts discourage harvesting during the second year. This is to allow the asparagus plants to establish more strength before the third-year harvest.
Harvesting Your Asparagus
Harvesting your asparagus plants can be done by cutting the spears using a knife or snapping them by hand.
Locate the tender part of the spears around the ground level and cut.
Don’t cut the asparagus spears below the ground level to preserve the growing potential of your asparagus plants.
Common Pests That Impact Asparagus Plants
Pests can weaken your asparagus and reduce their ability to retain sufficient nutrients during the growing season.
Here are the common types of insects that could infest your asparagus garden:
Cutworms feed on asparagus at the base and climb up at the tip causing deformed spear growth.
This insect can infest your asparagus even from the early growing stages until harvest season.
To better control this infestation, insecticides like permethrin can help get rid of cutworms in your garden.
Asparagus miners are shiny, black flies that are about 0.25 cm long.
This insect lays small, white eggs at the base of the asparagus stem.
When the plant is infested with miners, you’ll notice a reddish-brown discolouration on the stem.
Unfortunately, there are no chemical treatments to manage this problem.
However, the most important step to avoid it is to go for asparagus varieties that are fungi-resistant such as:
- Jersey Giant
- Jersey Knight
- Jersey Supreme
Common and spotted asparagus beetles
Common and spotted asparagus beetles feed on asparagus spears, causing browning and scarring of the plant.
The common asparagus beetle has large cream-coloured patches and black spots on each wing.
Its body has maroon and black borders around the rim.
Meanwhile, spotted asparagus beetles have a bright orange body with 6 black spots on each wing.
Naturally, a small parasitic wasp called Tetrastichus asparagi helps control the beetle’s eggs by feeding on them.
But for optimal pest control, use a good-quality insecticidal spray when:
- About 50 to 75% of the asparagus ferns contain larvae
- Around 5 to 10% of the plants are infested with adult beetles
- At least 1 to 2% of the spears are damaged or contain beetle eggs during harvest
It’s Worth the Wait
Growing asparagus from seed is a long-term commitment, but the reward of fresh asparagus spears for many years can be well worth the effort.
Here’s one last tip from our gardening experts: you can do this gardening activity with your kids. That way, they’ll grow up to see their efforts in the garden for years to come.