How to Grow Brachycome in Australia

Swan River daisy (Brachyscome iberidifolia) is a Western Australian native annual in the daisy family (Asteraceae). It is often sold as Brachycome, an older spelling of the genus. It is grown for low, ferny mounds covered in small blue, mauve or white daisies, for massed beds, edging, pots and hanging baskets. It grows wild from the Pilbara to the south coast and copes with poor soil, light frost and dry spells. The mistake most gardeners make is burying the tiny seed, which germinates best with light.

Three mistakes that matter

1. Burying the seed. Light helps Swan River daisy seed germinate, so seed pushed deep into the mix often never shows. Scatter it on the surface, press it in and cover it with no more than a dusting of mix.
2. Sowing into the wrong season. Plants flower poorly in very hot weather and can collapse in humid northern summers. In the tropics and subtropics, sow in late autumn and winter. Further south, sow in spring once frosts have passed.
3. Keeping the soil wet. Plants are sensitive to overwatering, roots rot in soggy ground, and damp leaves invite powdery mildew. Plant in free-draining soil, water at the base and let the surface dry between waterings.

When to plant

Warmth without heat is the cue. Seed germinates in moist mix at about 18 to 27°C. Sow after the last frost in cold districts, and after the humid heat has passed in the north. Flowers usually follow about 16 weeks after sowing. For a longer display, sow a small batch every 3 to 4 weeks through your window.

Sowings made late in the window run into summer heat and flower for a shorter time, so trim them after the first flush. In cool gardens, Melbourne Cup weekend in early November is the traditional marker for planting seedlings out.

Site, soil and setup

Give it the sunniest, best-drained spot you have. In the wild it grows on sandhills, clay flats, granite outcrops and even salty ground, so it needs no rich soil.

For more on heavy or sandy ground, see sandy, clay or loam.

Container growing

A compact, spilling habit makes Swan River daisy a natural for pots, window boxes and hanging baskets. A pot at least 25 cm across and 20 cm deep, about 7 L, holds one to three plants. A 30 cm hanging basket holds three. Fill either with a free-draining potting mix. Both 'White Splendour', bred for hanging baskets, and 'Blue Splendour', which spills over the rim, grow to about 25 cm. The third selection, 'Mixed Splendour', gives blue, mauve and white flowers in the one pot.

• Watering: water when the top 2 to 3 cm of mix feels dry. Check baskets daily in hot, windy weather; see watering pots in summer.
• Feeding: fish and seaweed blend at 25 mL per 9 L every fortnight while plants grow and flower. Potted plants need this steady, light feed.
• Position: full sun, or morning sun and afternoon shade in hot inland districts.
• Self-sown seedlings: plants often reseed into their own pots and baskets, so check old mix before tipping it out.

Sowing Seeds

Start Swan River daisy in a tray for tidy plants to set out, or scatter it where it is to flower for a massed carpet.

Starting under cover

• Fill a tray or punnet with fresh seed raising mix and water it well before sowing.
• Scatter the seed thinly on the surface and press it in, as in sowing tiny seeds. Cover it with no more than a dusting of mix.
• Sow thinly, because crowded seedlings are more prone to damping off (a fungal collapse of seedlings at soil level).
• Mist to keep the surface moist, and stand the tray somewhere warm and bright, out of hot direct sun.
• Seedlings usually appear within 2 to 12 days, though some seed lots take up to 3 weeks.
• Prick out (lift and separate) the seedlings into their own cells or pots when they are 3 to 4 cm tall.

Sowing direct

Rake the bed to a fine surface, scatter the seed thinly and rake it in lightly. A thin sprinkle of coarse sand over the seed stops heavy rain washing it away. Keep the surface moist until seedlings show, then thin them to about 20 cm apart.

Transplanting

Harden seedlings off first (a week or so of gradually longer spells outdoors that toughens soft growth), as in hardening off seedlings. Plant them 20 to 30 cm apart, at the depth they grew in the tray. Water in with seaweed solution at 30 mL per 9 L. Established plants handle a light frost, but young seedlings need shelter on frosty nights.

Care by growth stage

Sun, drainage and a light hand with water and feed decide how long a planting flowers. Established plants are drought tolerant, so a deep soak when the surface dries serves them better than a daily sprinkle.

Weeks count from sowing. A layer of mulch over the root zone, kept clear of the stems, holds moisture and helps plants flower. If growth stalls in poor soil, a light dose of all-purpose controlled release granular (NPK around 14-5-10) scratched into the soil can help.

Deadheading

Individual flowers do not last long, so regular trimming keeps plants bushy and brings on more buds.

• Pinch out the growing tips of young plants once they are growing strongly, for a bushier mound.
• Snip off faded flowers regularly while plants are in full bloom.
• After a full flush, shear lightly across the whole plant to bring on the next one.
• In late summer, trim off spent blooms again to carry flowering into autumn.
• Leave a few heads to dry on the plant if you want self-sown seedlings next season.
• Pull out plants that have finished, or cut them back if they still look healthy.

Companion planting

Swan River daisy suits the front of a sunny bed, a rockery, a path edge or the gaps between young shrubs.

Grows well with

• Everlasting daisy, another Western Australian annual daisy that wants the same sun and free drainage.
• Lavender, which likes the same sunny, well-drained spot and little water once established.
• Gazanias, which share its liking for sun, dry spells and sandy soil.

Keep apart

• Mint and other spreading runners, which smother the low mounds and compete for water.
• Pumpkin and other sprawling vines, whose big leaves shade out a low planting.
• Thirsty plants on daily watering, because constant wet brings root rot and mildew.

Harvesting Blooms

Cut sprays for posies when most of their flowers are open; these small native daisies usually have a long vase life.

• Pick early in the morning, when stems are full of water.
• Carry a bucket of water and stand stems in it as you cut.
• Cut whole sprays low down on the stem.
• For seed, wait for dry weather and for the dried ray florets (the coloured petals) to fall and show the seed in the centre.

If cut stems will not go into a vase straight away, keep them somewhere cool, between about 4 and 15°C. Keep collected seed dry in a paper envelope, somewhere cool, until the next sowing.

The short stems suit egg cups, small jugs and mixed posies of garden flowers.

Common problems

Seeds did not come up. Buried seed, dry mix or cold are the usual causes; see Three mistakes that matter. Read more

Thin, stretched seedlings. Too little light stretches them; move the tray into brighter light and prick out promptly. Read more

Flowering stopped in summer. Plants flower poorly in very hot weather; trim them, keep watering steady, and they often pick up again as it cools.

Plants died after flowering. Swan River daisy is an annual that finishes once it has set seed, so sow again or let self-sown seedlings take over. Read more

Pests and diseases

Swan River daisy has few serious troubles, and most start with damp leaves, wet soil or soft young growth.

Slugs and snails (Gastropoda). They chew seedlings and soft young plants, most of all after rain. Check under leaves and around rocks where they shelter by day, and set shallow beer traps dug slightly into the soil. Read more

Aphids (Aphididae). These small green, black or brown insects, around 2.5 mm long, cluster on soft tips and buds. Hose them off or snip the worst tips, and for repeat outbreaks spray soapy water or horticultural oil, never in hot weather. Read more

Powdery mildew (Oidium, Podosphaera and related fungi). White, powdery patches spread over the leaves, often as plants near the end of their life. Remove badly affected leaves and spray 1 part full-cream milk to 10 parts water. Read more

Root rot (soil-borne fungi and water moulds). In soil that stays wet, and in humid tropical and subtropical summers, plants wilt and collapse from the base. Pull and bin affected plants, then fix drainage before sowing there again.

Prevention first

• Keep the full spacing between plants so air moves through them.
• Water in the morning, so any damp leaves dry during the day.
• Check seedlings at dusk after rain for slugs and snails.
• Keep broad sprays off the bed so ladybirds, lacewings and hoverflies can keep aphids down.

Tips

1. Scatter seed under trees or over a bare, sandy patch, where it can form a loose carpet in spots little else will fill.
2. Plant it beside a path or a seat, where the light, sweet scent of the flowers can be noticed.
3. Edge the vegie patch with it, because the flowers draw bees and butterflies; see gardening for bees.
4. It suits a first sowing with children, since seedlings show within days and flowers follow within a few months; see growing from seed with kids.