How to Grow Violas in Australia

Pansies and violas are Viola species in the violet family, Violaceae. The group takes in the garden pansy (Viola × wittrockiana), heartsease or Johnny jump up (Viola tricolor) and small-flowered violas bred largely from Viola cornuta. All are grown as cool-season annuals for colour from autumn to spring, and their flowers are edible. The usual mistake is sowing them as the weather warms.

Three mistakes that matter

1. Sowing into the warm months. Pansies and violas are heat-sensitive, so spring sowings in warm areas flower briefly, then stretch and die back. Sow in late summer and autumn instead, at the times in When to plant.
2. Leaving the seed in the light. The seed germinates best in darkness, so seed left uncovered on a sunny bench often comes up patchily or not at all. Cover it with mix and shade the tray, as set out in Sowing Seeds.
3. Letting flowers set seed. Faded flowers left on the plant swell into seed pods, which draw energy from new flowers. Pinch spent blooms off regularly, as described in Deadheading, and plants can flower for months.

When to plant

Seed germinates best at about 17 to 22°C. Sow from late summer through autumn; in southern gardens, Anzac Day is a good marker for planting seedlings out. Cool and alpine gardens can add a spring sowing that flowers into summer.

At the hot start of the window, keep trays in the coolest, shadiest spot you have. Late sowings still flower, only in spring rather than winter.

Site, soil and setup

Give plants full winter sun in cool, temperate and Mediterranean gardens, and afternoon shade in warm zones or for spring plantings. Aim for at least four hours of direct sun, since heavy shade gives straggly plants. The soil should be moist and humus-rich but free-draining, at a pH of about 6.0 to 6.5.

Plant into a fresh spot or fresh potting mix each year. The fungi behind grey mould and damping off survive on old plant debris and in the soil.

Container growing

Shallow-rooted violas suit pots, window boxes and hanging baskets. One plant grows in a pot at least 20 cm wide and deep, about 5 L of mix. For a group, use at least 10 L of fresh potting mix: a 30 cm pot holds about 13.5 L, enough for three plants. Good choices are 'Bambini Mixed', 'Rococo Frilled Mixed', 'Swiss Giants Rhinegold' and, for baskets, 'Arkwright Ruby'.

• Watering: keep the mix evenly moist but never waterlogged, watering at the base in the morning.
• Feeding: water in fish and seaweed blend at 25 mL per 9 L every fortnight from planting until flowering ends.
• Position: full sun through winter, then move pots into afternoon shade as spring warms up.

Sowing Seeds

Raise pansies and violas in trays or punnets, where the seed gets the darkness, moisture and cool it needs.

Starting under cover

• Fill a clean tray or punnet with fine seed raising mix.
• Sow the seed thinly, cover it with 5 to 6 mm of mix, firm it gently and water well.
• Lay cardboard or newspaper over the tray to keep out the light.
• Keep the tray at the temperature in When to plant, and mist the surface so the mix stays moist but never wet.
• Seedlings usually appear in 1 to 4 weeks; lift the cover often to check.
• Remove the cover as soon as the first seedlings show, and move the tray into bright light straight away.

Sowing direct

Heartsease can also be sown where it is to grow. Scatter the seed thinly over raked, damp soil, barely cover it, firm it well and keep it moist.

Transplanting

• Prick out seedlings (lift each one into its own cell or small pot) once the first true leaves appear.
• Harden off the young plants before planting out (stand them outdoors for a little longer each day so they adjust to sun and wind).
• Plant out when seedlings are 5 to 10 cm tall, usually 7 to 12 weeks after sowing.
• Space small violas 15 to 20 cm apart, and pansies and heartsease 20 to 30 cm apart.
• Set each plant at the depth it grew in the punnet, never deeper.
• Water in with seaweed solution at half strength (15 mL per 9 L) to ease transplant shock.

Care by growth stage

Cool weather, even moisture and constant picking decide how long violas flower. They are light feeders, so feed gently. Weeks count from sowing.

If a stalled plant has healthy roots, scratch in a light dose of all-purpose controlled release granular (NPK around 14-5-10) at the label rate.

Deadheading

Start when the first flowers fade and keep going all season.

• Pinch spent flowers: take each one off with its stalk once the petals wilt, before a pod swells behind it.
• Large pansies: cut faded flowers just above a set of leaves with snips.
• After the first flush: trim sprawling stems back lightly to keep plants compact and bushy.
• Seed for next year: late in the season, leave a few pods to ripen, dry and split open.
• End of season: once heat makes plants straggly, pull them out and plant summer flowers such as zinnias.

Companion planting

Good partners share the cool season and the same steady moisture.

Grows well with

• Spring bulbs in pots: violas planted over the bulbs give winter colour before the bulbs flower through them.
• Lettuce and other cool-season vegetables: small violas tuck into the gaps between them and share the watering.
• Calendula: another cool-season edible flower, sown at the same time for a mixed picking bed.

Keep apart

• Tall, leafy plants on the north side: their winter shade makes violas straggly, with few flowers.
• Rock edgings and dense groundcover hard against seedlings: snails and slugs shelter there by day and feed at night.

Harvesting Blooms

Pick flowers for eating or for small vases once they are fully open, first thing in the morning or just before you use them.

• Eat only flowers from plants you know have not been sprayed.
• Pinch each flower off at the top of its stalk for the kitchen.
• For a vase or a float bowl, cut the flower with its whole stem.
• Check each flower for aphids before using it.
• Wash each flower well before eating it.
• Pick often: regular picking keeps plants making new flowers.

Picked flowers wilt quickly. Store them on a damp paper towel in an airtight container in the fridge for a few days, removing any that wilt. Use them in salads, ice cubes or on cakes; heartsease has a faint musky flavour.

Common problems

Seedlings collapse at soil level. Damping off (Pythium species and Rhizoctonia solani) rots young stems, most often in wet, cold seed raising mix. Read more

Seedlings grow tall and pale. Warm conditions and too little light stretch them, so move trays into bright light in a cooler spot. Read more

Plants are straggly with few flowers. Check two causes: too much shade (see Site, soil and setup) and seed pods left on the plant (see Three mistakes).

Seedlings come up all over the garden. Heartsease self-sows readily; pull unwanted seedlings while they are small, and deadhead to limit it.

Pests and diseases

Most trouble comes from snails, sap-suckers and fungi that thrive in mild, damp weather.

Garden snail (Cornu aspersum) and slugs. They feed after dark, chewing holes in leaves and eating young seedlings, and leave slime trails. Collect them by torchlight, set beer traps, or run copper tape around plastic or wooden pots and beds, not corrugated iron, which it corrodes. Read more

Aphids (family Aphididae). Clusters of these small sap-suckers gather on shoot tips, buds and leaf undersides, causing yellowing, poor growth and sticky honeydew; they can also carry viruses. Hose them off, or spray insecticidal soap at the label rate. Read more

Grey mould (Botrytis cinerea). Fading flowers turn soft and grey with mould in cool weather with heavy dew. Pick off affected flowers and leaves, clear up fallen petals and water at soil level.

Powdery mildew (Golovinomyces orontii). A white, powdery film spreads over the leaves, often starting on older, lower ones. Remove the worst leaves, water in the morning at the roots, and spray 1 part full-cream milk to 10 parts water. Read more

Black root rot (Thielaviopsis basicola). Plants stay stunted and the roots turn black. The fungus lingers in soil, so pull affected plants, improve drainage and replant elsewhere.

Prevention first

• Space plants as set out in Sowing Seeds, so air moves freely between them.
• Keep the leaves dry by watering as set out in Care by growth stage.
• Scrub and rinse seed trays before reuse, as black root rot carries over on dirty trays.
• Check new seedlings for snails and aphids on each visit, including under the leaves.

Tips

1. Choose violas over pansies for frostier or part-shaded spots: they tolerate both a little better, and their smaller flowers come in greater numbers.
2. Check with your local council before letting heartsease self-sow near bushland, as its weed potential varies by area.
3. Brisbane's Roma Street Parkland has grown blue violas among its flowering annuals; in the subtropics, success depends on timing.