How to Grow Aster

Asters are available in a range of sizes, from compact plants that grow to 20 cm, to tall Asters that can reach 70 cm. Small Aster varieties are ideal for garden borders and pots, while larger Asters create a beautiful display in the middle or back of a garden bed.  

Flower types include heavily ruffled, slender petals, and open daisy-like flowers with yellow centres. There's a rainbow of Aster colours, including pink, purple, red, white, blue and yellow. 

Yates Aster Colour Carpet is a compact and colourful variety with masses of double blooms in white, pink, mauve and purple. 

There are also other plants commonly known as 'Asters', including the Michelmas or Easter Daisy (Symphyotrichum novi-belgii, formerly known as Aster novi-belgii). Although these perennial Asters are in the same plant family as Callistephus chinensis, they're different plants and so it's important to know which type of 'Aster' you're growing.  

Choose a spot in the garden with free-draining soil that receives at least six hours of sunshine a day.  

Where the plants are to grow, enrich the soil with Yates Dynamic Lifter Soil Improver & Plant Fertiliser. It contains rich organic matter to help improve soil health and provide the plants with gentle slow-release organic nutrients as they establish. 

Aster seed can be sown direct where the plants are to grow. Alternatively, sow and raise seedlings in trays or punnets for later transplanting. In temperate and cool climates, sow seed in spring to early summer. In tropical and sub-tropical climates, sow seed from mid-winter to early summer.  

To sow seed direct into a garden bed, sow a few seeds 6 mm deep in multiple spots, at the distance indicated on the seed pack for that variety (usually 15–50 cm apart). Firm down and water gently. Keep the soil moist and seedlings will emerge in 10-14 days. Later, thin to the two strongest seedlings at each position.  

To grow seedlings for transplanting, sow seed 6 mm deep into trays or punnets of Yates Specialty Potting Mix Cuttings & Seeds, firm down and water gently. Keep the seedling tray or punnet in a warm sunny spot and keep moist. Seedlings will take 10-14 days to emerge and can be transplanted into their final position when they're large enough to handle (usually after 4-6 weeks). In cool climates, delay sowing seeds or transplanting seedlings into the garden until after the danger of frost has passed.  

As soon as Aster seedlings appear (or you have transplanted seedlings), protect them from Snails and Slugs with a light sprinkling of Yates Snail & Slug Bait. Apply a layer of mulch, like sugar cane or pea straw, around the base of the plants to help retain soil moisture. 

Keep the soil moist as the plants grow, particularly during dry spells. Water gently around the base of the plants, rather than over the leaves, to help reduce the chance of leaf diseases. 

To promote healthy growth and lots of flowers, feed every 1-2 weeks with a high-potassium liquid fertiliser like Yates Thrive Roses & Flowers Liquid Plant Food. It's as easy as diluting 1–2 capfuls in a watering can, so you can water and feed at the same time.  

When growing tall varieties of Asters, stakes may be required to support the plants as they grow. 

To promote tidy plants and a longer flowering season, regularly remove spent blooms.  

When picking Aster flowers for a vase, choose flowers that are half opened and remove any leaves that will sit below the water.  

Choose a pot at least 20 cm in diameter with good drainage holes. Larger Aster varieties will require a larger pot. Place in a position that receives at least six hours of sunshine a day.  

Fill the pot with a good quality premium potting mix like Yates Premium Potting Mix with Dynamic Lifter.  

Aster seed can be sown direct where the plants are to grow. Alternatively, sow and raise own seedlings in trays or punnets for later transplanting. In temperate and cool climates, sow seed from spring to early summer. In tropical and sub-tropical climates, sow seed from mid-winter to early summer.  

To sow seed direct into a pot, sow a few seeds 6 mm deep in multiple spots, at the distance indicated on the seed pack for that variety (usually 15–50 cm apart). Firm down and water gently. Keep the potting mix moist and seedlings will emerge in 10–14 days. Later, thin to the two strongest seedlings at each position.  

To grow your own seedlings for transplanting, sow seed 6 mm deep into trays or punnets of Yates Specialty Potting Mix Cuttings & Seeds, firm down and water gently. Keep the seedling tray or punnet in a warm sunny spot and keep moist. Seedlings will take 10–14 days to emerge and can be transplanted into their final position when they're large enough to handle (usually after 4–6 weeks).  

As soon as Aster seedlings appear (or you have transplanted seedlings), protect them from Snails and Slugs with a light sprinkling of Yates Snail & Slug Bait. Mulch around the base of the plants with organic mulch like sugar cane or pea straw to help retain potting mix moisture. 

Keep the potting mix moist as the plants grow. Water gently around the base of the plants, rather than over the leaves, to help reduce the chance of leaf diseases. 

To promote healthy growth and lots of flowers, feed every 1-2 weeks with a high-potassium liquid fertiliser like Yates Thrive Roses & Flowers Liquid Plant Food. It's as easy as diluting 1–2 capfuls in a watering can, so you can water and feed at the same time.  

When growing tall varieties of Asters, stakes may be required to support the plants as they grow. 

To promote tidy plants and a longer flowering season, regularly remove spent blooms.  

When picking Asters for a vase, choose flowers that are half opened and remove any leaves that will sit below the water.  

Asters do best when fed regularly with a high-potassium fertiliser like Yates Thrive Roses & Flowers Liquid Plant Food. 

Yes, Asters need at least six hours of direct sun a day.  

China Asters (Callistephus chinensis) are annuals, meaning they grow and flower within one year, before dying. They need to replanted each year. 

No, annual Asters are not frost tolerant. 

Depending on the variety, it can take 14–16 weeks after sowing to start flowering. 

To help reduce the build up of pests and diseases, it's best to grow Asters in a different spot each year.  

Asters are prone to a few common pests, including Aphids. Aphids are tiny green, brown, yellow or black sap-sucking insects that cluster on leaves and flower stems. They can damage leaves and flowers and plant health will suffer. 

As soon as any Aphids are noticed, spray the plants with Yates Rose Gun. It's a ready-to-use spray that controls common insect pests like aphids, as well as other pests like Caterpillars, Whitefly and Mites.  

A fungal problem that commonly affects Aster plants is Powdery Mildew disease, particularly as the leaves age and if the weather is damp or humid. Powdery Mildew appears as white powdery spots on the leaves and large infections cause leaves to yellow and die prematurely. 

Help reduce Powdery Mildew by watering plants around the base, rather than over the leaves, and water only in the morning. As soon as you notice disease symptoms, spray plants with Yates Rose Gun, repeating as required. 

Rust is a fungal disease that leads to leaves developing powdery brown or orange pustules.

Help reduce Rust by watering plants around the base, rather than over the leaves, and water only in the morning. As soon as you notice disease symptoms, spray affected plants with Yates Rose Gun, repeating as required. 

Depending on the variety, it can take 14–16 weeks after sowing for Asters to flower. So, more time may be required. Asters flower best when grown in a position with at least six hours of sunshine a day. Asters grown in shadier positions will not flower as well. And to help promote the best possible flower show, keep the soil or potting mix moist and feed every 1–2 weeks with a liquid fertiliser like Yates Thrive Roses & Flowers Liquid Plant Food. It's high in flower-promoting potassium. 

Aster Yellows is a bacterial disease that can cause deformed growth and flowers in plants like Asters, as well as Carrots, Lettuce, Onions and Spinach. It is commonly spread via leafhoppers. Aster Yellows is found in Asia, Europe, South and North America. Fortunately, this disease is not present in Australia.