How to Grow Chrysanthemums in Australia

Seed-grown chrysanthemums are cottage daisies (family Asteraceae) grown for cut flowers, chiefly painted daisy (Glebionis carinata) and Shasta daisy (Leucanthemum x superbum). Unlike the florist chrysanthemum (Chrysanthemum morifolium) sold in pots for Mother's Day, they start from seed, and garland daisy (Glebionis coronaria) also gives edible leaves. The usual mistake is burying seed that needs little or no cover.

Three mistakes that matter

1. Burying the seed. Painted daisy and Shasta daisy seed wants 1 to 2 mm of cover at most, and seed sown deeper often fails to appear. Press it onto the mix, sprinkle a fine layer over it and keep it moist.
2. Sowing 'May Queen' unchecked. 'May Queen' is ox-eye daisy (Leucanthemum vulgare), a noxious weed that needs a permit to sow in Victoria. Parts of New South Wales say not to grow it. Ask your state weed authority first; deadheading stops seed, not creeping roots.
3. Leaving perennials in wet winter soil. Shasta daisy crowns rot in ground that stays wet through winter, and the clump dies out. Plant perennials in free-draining soil or a raised bed.

When to plant

Seed germinates best at 18 to 25°C, though painted daisy prefers the cool end and starts in soil from about 10°C. Autumn is the main window, from February until about Anzac Day in the south. The perennials also take a spring sowing. On the frost-free subtropical and temperate coast, sow garland daisy for leaves in small batches most of the year.

At the hot edge of a window, raise trays out of afternoon sun. Where frosts are hard, hold 'Pure White' and garland daisy until they have passed.

Site, soil and setup

A Shasta daisy clump stays in place for several years, so it needs no yearly rotation; move annual daisies to a fresh bed each year. For ground that stays soggy after rain, read about waterlogged garden soil.

Container growing

Low 'Pure White' and feverfew 'Golden Ball' suit pots best, and garland daisy grows well in one for leaves. Use a pot at least 30 cm wide and 30 cm deep, about 20 L, which also holds one 'Alaska'. Fill it with premium potting mix.

• Watering. Water when the top of the mix feels dry, and never leave the pot standing in water. See watering pots through summer.
• Feeding. Give fish and seaweed blend at 25 mL per 9 L every fortnight. From the first flowers, switch to liquid potash at the label rate, also fortnightly. The synthetic option is a controlled release fertiliser for containers, mixed in at planting.
• Position. Full sun, with afternoon shade during heatwaves.

Propagating by Division

Every variety starts from seed, and an established Shasta daisy clump can then be multiplied by rooted pieces or division.

Cutting propagation

Shasta daisy stems that lie on the ground often root where they touch, a habit called self-layering. Dig a rooted stem from the edge of the clump with a trowel, keeping plenty of root. Trim back a few leaves to reduce water loss, pot it in potting mix and stand it in shade. Plant it out once new leaves appear and roots show through the drainage holes. Young basal shoots also strike as cuttings; see how to take cuttings.

Starting under cover

• Fill clean trays or punnets with fresh seed raising mix and firm it lightly.
• Sow at the depth in the table below, covering fine seed with only a dusting of mix.
• Keep trays at the temperature under When to plant, in bright light, and mist them so the seed stays put.
• Seedlings emerge in 1 to 4 weeks, depending on the variety.
• Prick out each seedling into its own small pot once its first true leaves open.

Sowing direct

Garland daisy, 'Alaska' and, where allowed, 'May Queen' can go straight into a prepared bed in mild weather. Thin the seedlings to the spacing in the table, and eat the garland daisy thinnings.

Transplanting

Plant seedlings out 4 to 6 weeks after sowing. Harden them off first (a week or so of gradually longer spells outdoors that toughens soft growth), as in hardening off seedlings. Water each one in with seaweed solution at 30 mL per 9 L.

Dividing a clump

Divide a Shasta daisy clump every 2 to 3 years, in early spring as growth starts or in autumn after flowering. Fewer, smaller flowers and a bare centre are the signs, as in dividing perennials.

• Lift the clump with a garden fork, keeping as many roots as possible.
• Cut it into pieces with a sharp knife, each with several shoots and healthy roots.
• Discard the woody centre and any diseased pieces.
• Replant the pieces 30 cm apart at their old depth, and water them in.

Care by growth stage

Steady moisture and a switch to potassium as flowering starts decide how long it lasts. Heavy feeding grows lusher plants, not necessarily more flowers, so keep nitrogen modest.

Weeks count from sowing painted daisy. Garland daisy flowers from about 10 weeks and 'Alaska' from 14 to 20 weeks, though many Shasta daisies wait until their second summer. Garland daisy grown for leaves takes fish emulsion at half strength every fortnight instead.

Feed an established Shasta clump each spring as growth resumes. Spread 5 cm of compost and pelletised chicken manure at 100 g per square metre. The synthetic option is a controlled release all-purpose granular (NPK around 14-5-10).

Disbudding and Deadheading

Pinching gives bushier plants with more stems, disbudding gives fewer but larger blooms, and deadheading keeps flowers coming while stopping weedy seed.

• Pinch out the growing tips of painted and garland daisies before the first buds, once plants are about 20 to 40 cm tall.
• For a larger Shasta bloom on a long stem, rub out the side buds below the main bud while they are small.
• Deadhead spent flowers to a leaf or side bud, so more follow.
• After the main flush, cut flowered Shasta stems back to the low leaves at the base.
• Remove dead Shasta growth at ground level any time between autumn and early spring.
• Cut off 'May Queen' and feverfew flowers before seed forms, because both self-sow freely.

Companion planting

These daisies suit a cottage border or the edge of a vegie patch.

Grows well with

• Vegetable crops, which gain from the bees and beneficial insects the flowers draw.
• Cabbage, kale and other brassicas, beside which garland daisy gives a leafy green that cabbage white caterpillars leave alone.
• Low 'Pure White' at the front of a border, which shades the soil without crowding taller daisies.

Keep apart

• Bushland edges and paddocks, where self-sown daisies spread; ox-eye daisy invades pasture and native vegetation.
• Crowded plantings, where damp, still air favours powdery mildew.
• Small, slow plants beside a Shasta clump, which spreads by rooting stems and can crowd them out.

Harvesting Blooms

Cut daisies when the flowers are fully open or nearly so, because stems cut in tight bud may never open.

• Pick in the cool of the morning and stand the stems in water straight away.
• Cut each stem low, to a leaf or side bud, so the cut doubles as deadheading.
• Strip the leaves from the lower third of each stem.
• Pick garland daisy leaves and tips from about 30 days after sowing, at 15 to 20 cm tall and before flowering, as a cut-and-come-again green.

Shasta daisies usually last a week or more in a vase, and painted daisies also dry well. Garland daisy leaves turn bitter as plants age or in hot weather, so pick them young and use them fresh.

Cook garland daisy leaves briefly in stir-fries and soups, since overcooking makes them bitter. The other daisies are ornamental only. Shasta daisy is mildly toxic if eaten. Both it and feverfew can irritate skin, and feverfew is unsuitable in pregnancy or breastfeeding.

Common problems

Seeds did not come up. Seed buried too deep (see Three mistakes that matter), or trays that dried out or ran cold, are the usual causes. Read more

Pale, stretched seedlings. Seedlings raised in poor light stretch and flop. Read more

Lush leaves but few flowers. Soil that is too rich, or too much nitrogen, grows foliage instead of flowers; move to the potash feeds under Care by growth stage.

Fewer, smaller Shasta flowers. The clump is overcrowded; divide it as under Dividing a clump.

Pests and diseases

Sap-suckers and powdery mildew cause most trouble in the bed, and damping off in trays.

Aphids (Aphididae). These sap-sucking insects crowd shoot tips and buds, leaving sticky honeydew that grows sooty mould. Hose them off, or spray horticultural oil or soapy water, but not in hot weather. Read more

Western flower thrips (Frankliniella occidentalis). These tiny insects feed in flowers and leaves and spread tomato spotted wilt virus, which weeds also carry. Watch with yellow or blue sticky traps. Read more

Two-spotted mite (Tetranychus urticae). Feeding leaves yellow stippling, mostly under the leaves, and numbers climb fast in hot, dry weather. Avoid broad insecticides, which kill the predatory ladybirds and mites that keep them down. Read more

Woolly bears (Spilosoma species). These hairy caterpillars of a native tiger moth feed on daisies in winter. Pick them off regularly, wearing gloves, because the hairs irritate skin.

Powdery mildew (Golovinomyces species). White patches spread across the leaves, older ones first. Remove the worst and spray 1 part full-cream milk to 10 parts water. Test a few leaves 24 hours beforehand, and respray after heavy rain. Read more

Damping off (Pythium species and Rhizoctonia solani). These soil-borne pathogens rot seedlings at the base, so they collapse in the tray. Read more

Prevention first

• Sow in fresh seed raising mix in clean trays.
• Space plants as in the variety table, and water at soil level in the morning.
• Keep weeds down around the bed, since they shelter thrips and the virus.
• Check shoot tips and leaf undersides every week in warm weather.

Tips

1. Plant 'Pure White' where it catches morning sun, because its flowers open when the sun reaches them.
2. Let a couple of garland daisy plants flower, and remove the flower heads from the rest so they keep making leaves.
3. Tell the two white daisies apart by the flower. Shasta daisy flowers are 5 to 8 cm wide with 20 to 40 petals; ox-eye flowers are 3 to 5 cm.