Start from seed: September-February
Optimum soil temperature for germination: 20-28°C
Plant seedlings: September-February
Plant spacing: 30 cm
Days to maturity: 50-70 days
Introduction
Swiss chard, also known as silverbeet in Australia, belongs to the Amaranthaceae family, which also includes beetroot and spinach.
Swiss chard has been cultivated for thousands of years, with its origins traced back to the Mediterranean region. Despite its name, Swiss chard actually originated in Sicily, not Switzerland. The “Swiss” prefix was added by 19th century seed catalogue publishers to distinguish it from French spinach varieties. The name “chard” comes from the Latin “cardus” meaning thistle, though it has no thorns.
The plants form upright rosettes of large, crinkled leaves with prominent ribs and stems. Traditional varieties have white stems and dark green leaves, while newer varieties like “Rainbow Chard” feature stems in vibrant colours including yellow, pink, orange, and red. Botanically, it’s a biennial plant usually grown as an annual.
Site and soil
Swiss chard grows well in Canberra’s climate and can be grown almost year-round with some protection. Ideally, choose a location that receives at least 6 hours of sunlight per day, although leafy greens are tolerant of more shade than fruiting plants. Afternoon shade is beneficial in the heat of summer.
Prior to planting, incorporate plenty of compost or well-rotted manure into the soil and complete organic fertiliser. Swiss chard prefers a fertile, well-draining soil with a pH of 6.0-7.0. It is a heavy feeder so requires adequate macro and micronutrients for abundant leaf production.
If growing in pots, use a high-quality potting mix enhanced with organic fertilizer. Choose containers at least 30cm deep to accommodate the root system.
For details on preparing the soil and pots, including the use of lime, dolomite, gypsum and fertilisers please refer to the COGS guide to garden bed preparation.
Planting Seeds and Seedlings
Swiss chard can be direct-sown or started in seedling trays. In Canberra, the ideal and planting and sowing times are between September and February.
Seeds should be planted in cell trays or seedling trays to a depth twice the size of the seed. Seeds are multi lobed which means you may get 2 or 3 seedlings emerging from 1 seed. Therefore, just plant 1 seed per cell if using cell trays and if direct seeding sow seeds about 5cm apart. The optimum soil temperature for germination is between 10-30°C, with seeds typically germinating within 5-10 days. Once seedlings develop their first true leaves, thin them to about 20-30cm apart.
If raising seedlings, transplant when plants have 4-5 true leaves. Plant seedlings approximately 20-30cm apart. After planting, water them in with a seaweed solution to minimize transplant shock. Mulch around the plants with organic matter such as straw, sugar cane mulch, or leaf mould to conserve moisture and suppress weeds.
Cultivation
Swiss chard is quite cold-tolerant and can withstand light frosts, making it ideal for Canberra gardens. It grows best in mild to cool weather but is more heat-tolerant than spinach. During the hottest part of summer, provide some afternoon shade to prevent leaf scorch.
Consistent soil moisture and adequate nutrients are important for producing tender, flavourful leaves. Water regularly, particularly during dry periods, aiming to keep the soil evenly moist but not waterlogged. Using drip irrigation or watering at the base of plants helps prevent foliar diseases.
A mid-season side dressing of complete organic fertilizer will support continued productivity. A monthly foliar spray with seaweed solution; a mix of worm juice, seaweed and compost tea; or trace elements will help boost growth and resilience to pests and diseases.
Removing any flower stalks as they appear will extend the productive life of the plants. Swiss chard is a cut-and-come-again vegetable—harvesting the outer leaves regularly encourages the plant to produce new growth from the centre.
In winter, growth will slow significantly, but plants usually survive to produce new leaves in spring. Caterpillar tunnels cloaked in horticultural plastic will protect plants during Canberra’s coldest periods and extend the harvest season.
Harvesting
Harvesting can begin when plants are about 15-20cm tall, typically 50-70 days after sowing. Fully expanded, outer leaves should be harvested first, cutting them about 3cm above the base of the plant. Do not harvest more than 1/3rd of the plant at a time in order to retain enough leaves for photosynthesis to sustain continued growth. New leaves will continue to grow from the centre, providing multiple harvests from a single planting over many months.
For baby leaf production, plants can be cut when leaves are 8-15cm tall, about 2.5cm above the crown to allow regrowth.
The flavour is best when leaves are young and tender. Larger, older leaves tend to develop a stronger taste and tougher texture. During hot weather, harvest in the morning when leaves are crisp and at their freshest.
Swiss chard can remain productive for up to two years in favourable conditions, but most gardeners replant annually for the best quality produce.
Problems
The best approach is to have a reliable Australian reference book to identify problems. Garden Pests, Disease and Good Bugs by Denis Crawford is recommended.
A general strategy to follow with any problem is to observe the plant carefully before taking action. Identify the problem then carefully consider the course of action. For example, with pest insects, you often can see a predator nearby. If you watch and wait the predator may deal with the problem for you. Beneficial predatory insects which feed on pest insects can be purchased from suppliers such as Bugs for Bugs. If the problem needs further action the above recommended book has suggestions.
Practicing good garden hygiene, crop rotation, and maintaining plant vigour by providing adequate nutrients are key strategies for prevention.
Swiss chard is relatively pest and disease resistant, but several issues can occur in Canberra gardens:
Cercospora leaf spot: This fungal disease causes grey to brown round spots with reddish-brown margins on older leaves. The plant tissue often dries and falls out leaving holes. Prevent by ensuring good air circulation between plants, avoiding overhead watering, and practicing crop rotation. Disease can be carried on seed so avoid saving seed from diseased plants and use disease-free seed. Remove and dispose of affected leaves promptly.
Leaf miners: These pests tunnel through leaves, creating winding trails. Remove and destroy affected leaves to prevent spread. Covering plants with fine mesh can prevent the adult flies from laying eggs.
Aphids: These small sap-sucking insects can cluster on the undersides of leaves, causing distortion and stunting. Control with insecticidal soap, neem oil, pyrethrin or by encouraging beneficial predators like ladybugs and lacewings. Look for aphid mummies which are evidence that the aphid has been parasitised. Eggs can also be parasitised and will appear bronze in colour. Generally speaking, plants that are high in soluble nitrogen (nitrates and ammonia) are prone to attack by sap sucking insects. Ideally avoid using soluble nitrogen fertilisers and ensure plants have adequate trace elements. This can be achieved by using foliar sprays.
Slugs and snails: These are particularly problematic in damp conditions and can devastate young seedlings. Use organic slug baits (iron EDTA), beer traps, or copper tape as deterrents. Keeping the area around plants clear of debris reduces hiding places.
Frost damage: severe frosts can damage stems which provides an entry for pathogens causing secondary infections. Symptoms are brown streaky areas and soggy patches on the stems. Damage can be prevented by erecting caterpillar tunnels cloaked in horticultural plastic over the plants.
Recommended Varieties
Several Swiss chard varieties perform well in Canberra’s climate:
- Fordhook Giant: The standard green variety with white stems and dark green, crinkled leaves. Highly productive and tolerant of both heat and cold. Excellent flavour and long harvest period.
- Rainbow Chard (Five Colour Mix): Features stems in various colours including red, pink, yellow, orange, and white. Slightly milder flavour than Fordhook Giant but equally productive. Adds beautiful colour to both the garden and plate.
- Ruby Red (Rhubarb Chard): Deep green leaves with striking red stems. Best sown after risk of frost has passed as it can bolt in cold conditions.
- Bright Lights: Similar to Rainbow Chard with multi-coloured stems. More bolt-resistant but slightly less frost-hardy than Fordhook Giant.
- Lucullus: Green leaves with white stems. Particularly heat-tolerant, making it good for summer planting in Canberra.
References
- Bubel, Nancy. The New Seed-Starters Handbook. Rodale Books, 2018.
- Crawford D. Garden Pests, Disease and Good Bugs. Australia: ABC Books; 2015.
- Dove, Helena. Botany of the Kitchen Garden, Kew Publishing, Royal Botanic Gardens Kew, UK, 2023.
- Fanton, Michel and Jude. The Seed Savers Handbook. The Seed Savers Network, Australia, 1993.
