How to Grow Californian Poppies in Australia

Californian poppy (Eschscholzia californica) is a sun-loving annual or short-lived perennial in the poppy family, Papaveraceae, grown for its cup-shaped flowers over feathery blue-green leaves. It flowers for months in lean, dry, sunny ground, and the step most gardeners get wrong is letting it drop seed. It has escaped gardens and is regarded as an environmental weed in parts of Western Australia, New South Wales and Victoria.

Three mistakes that matter

1. Moving seedlings. Californian poppy grows a deep taproot and does not transplant well, so seedlings dug up and moved often wilt and fail. Sow where the plants are to flower, or in single cells, and plant out small with the root ball whole.
2. Rich soil and heavy watering. Manure, regular feeding and soil kept wet give lush leaves, few flowers and plants that rot at the base. Grow it in lean, free-draining soil and water only once the soil is dry 10 cm down.
3. Letting pods ripen. Ripe pods split open and throw seed up to about 1.8 m, and the seedlings spread along roadsides and into bushland. Pick off faded flowers and green pods every few days, as set out in Deadheading.

When to plant

Seed comes up in cool to mild soil, roughly 10 to 22°C, and plants flower most freely while the nights stay cool. Northern gardens sow through autumn and winter, southern gardens mainly in spring, and winter-rain gardens can use both. With regular deadheading, one sowing flowers for months.

Where frost lingers, sow direct after the last hard frost, or start seed in cells 2 to 3 weeks before it. Sow early in your window, because plants flowering into summer heat slow down.

Site, soil and setup

Give Californian poppy full sun, at least 6 hours a day, since it does not grow well in shade. Sandy or stony ground suits it, and it grows best in neutral to alkaline soil.

Avoid a patch where seedlings rotted off last season: the fungi behind damping off live on in old plant debris.

Container growing

Use a pot of at least 20 L with drainage holes. A standard 40 cm pot holds about 28 L, and a 33 cm pot only about 18 L. The most compact is 'Sundew', at about 20 cm, and 'Red Chief', 'Alba Cream White' and 'Carmine King' are also described for containers.

Fill the pot with a free-draining potting mix. Bagged mix can carry Legionella bacteria, so wet it before opening, wear a mask and gloves, and wash your hands afterwards.

• Watering: pots dry out faster than beds, so water more often, but let the top of the mix dry between drinks.
• Feeding: potted plants may need a little extra. Give worm casting liquid diluted to weak tea colour once a fortnight while they flower.
• Position: full sun for 6 hours or more.

Sowing Seeds

Sow Californian poppy straight into the bed where it is to flower, or into single cells where frost lingers.

Sowing direct

• Rake the soil fine, then scatter the seed thinly or sow it in shallow rows.
• Cover it with about 3 mm of fine soil, firm the surface and water with a fine spray.
• Keep the soil moist but never soggy until the seedlings are up, usually in 10 to 21 days.
• Thin to 20 to 40 cm apart once the first true leaves appear: closer gives a solid drift, wider lets air move in humid districts.

Starting in cells

• Fill cells or small pots with seed raising mix and sow two or three seeds 3 mm deep in each.
• Keep the strongest seedling in each cell and cut the others off with scissors.
• Harden off the seedlings (stand them outdoors for a few hours, then longer each day, until they take full sun and wind).
• Plant them out at 5 to 10 cm tall with the root ball whole. Water in with seaweed solution at half strength, 15 mL per 9 L.

Every variety in the range is the same species, sown and grown the same way. They differ in colour, height and petal form, and 'Mission Bells' is sold as California poppy but is the same plant.

Iceland, Shirley and Flanders poppies belong to a different genus, Papaver, and are covered in the separate Poppy guide.

Care by growth stage

Sun, lean soil and a light hand with the hose decide how well Californian poppy flowers, and plants in the ground rarely need feeding.

If growth stalls in a pot, scratch a little all-purpose controlled release granular (NPK around 14-5-10) into the mix at the label rate.

Deadheading

Deadheading keeps the plants flowering, and it keeps the seed out of the wider landscape. Californian poppy is naturalised along the Snowy River in Victoria and between Perth and Augusta in Western Australia. Before sowing near bushland, a creek or a roadside reserve, check your state and council weed lists.

• Every few days in flower: snip off faded flowers and any green pods before the pods dry and split.
• How to cut: use sharp snips or secateurs just above a set of leaves.
• Disposal: put spent flowers and pods in the general waste bin, not the compost or green waste bin.
• Stray seedlings: pull any that come up outside the bed while they are small.
• End of the season: pull plants out once flowering fades. In mild coastal gardens some live on for another year, so keep deadheading those.

Companion planting

Good neighbours share its taste for sun, lean soil and little water.

Grows well with

• Cornflowers: their blue flowers set off the yellow poppy varieties in a sunny bed.
• Larkspur: the other blue partner often named for the yellow varieties.
• The edge of the vegie patch: bees and hoverflies visit the flowers, and hoverflies are natural enemies of aphids.

Keep apart

• Lettuce: its shallow roots need daily water in hot weather, which keeps poppy roots too wet.
• Sunflowers on the north side: they shade a plant that will not flower well out of full sun.

Harvesting Blooms

Cut stems for the vase when the buds show colour but have not yet opened.

• Cut each stem low, just above a set of leaves, so more buds follow on the plant.
• Stand the stems in water straight away; they need no searing.
• Each flower lasts 3 to 4 days, and later buds on the same stem keep opening for about a week.
• Short stems suit small jars, bud vases and posies.

The blooms do not store once cut, so pick them on the day you want them. Pull out each faded flower as the next bud opens.

Common problems

Seed does not come up. Seed sown too deep, soil that dried out, or soil outside the range in When to plant is the usual cause. Read more

Seedlings collapse at soil level. Damping off (a rot of seedlings at soil level, caused mainly by Pythium species and Rhizoctonia solani) strikes most in wet soil. Read more

Plants wilt after moving. See the first point in Three mistakes that matter.

Lush leaves, few flowers or rot at the base. See the second point in Three mistakes that matter, and raise the bed or grow in pots where soil stays wet. Read more

Flowers stay closed. The flowers close at night and in cloudy, cold or windy weather, then open again in sun, which is normal.

Pests and diseases

Californian poppy has few serious pests, and most trouble follows crowding, humidity and wet soil.

Aphids (family Aphididae). Clusters of small sap-suckers on shoot tips and buds leave malformed leaves and sticky honeydew. Hose them off, or spray insecticidal soap onto the undersides of the leaves. Read more

Powdery mildew (Erysiphe species). White powdery patches spread over the leaves, most often in humid weather and crowded plantings. Remove the worst leaves and spray 1 part full-cream milk to 10 parts water. Read more

Grey mould (Botrytis species, mainly Botrytis cinerea). Ageing petals turn soft and brown under a grey mould in cool weather with heavy dew. Remove affected flowers promptly and water at soil level.

Prevention first

• Keep to the spacing in Sowing Seeds, so rain and dew dry off quickly.
• Water the soil rather than the foliage, early in the day.
• Start cell-grown seedlings in fresh seed raising mix, never last season's.
• Check shoot tips and buds for aphids once a week.

Tips

1. Next to bushland, a creek or a roadside reserve, grow Californian poppy in pots on paving, where stray seed cannot reach bare soil.
2. Plant it where you pass in the middle of a sunny day, when the flowers are fully open.
3. Sow 'Purple Gleam' beside an earlier variety to stretch the display, since it is described as a late bloomer.