How to Grow Nigella in Australia

Love-in-a-mist (Nigella damascena), usually sold as nigella, is an annual in the buttercup family, Ranunculaceae, grown for cut flowers and dried seed pods. Each blue, white or pink flower sits in a ruff of fine bracts, the mist of its name, then swells into a striped, balloon-shaped pod. It is a cool-season flower here, and the usual mistake is a late spring sowing that runs straight into summer heat.

Three mistakes that matter

1. Raising seedlings in punnets and moving them late. Love-in-a-mist grows a long taproot and resents being moved, so seedlings kept too long in punnets often stall after planting out. Sow where plants will flower, or move tray seedlings while still small (see Sowing Seeds).
2. Sowing into warming weather. Plants do poorly in hot weather, and spring sowings often give smaller plants with smaller flowers. In most zones, sow in autumn so seedlings build roots over winter and flower earlier and larger.
3. Sowing into heavy, wet soil. This plant needs very free-draining ground, and seedlings in wet soil are the ones most likely to rot at the base. Loosen the bed or build it up before sowing, as set out in Site, soil and setup.

When to plant

Seed germinates in cool soil, at about 15 to 20°C, so the main sowing runs from late summer through autumn as the heat eases. Cool and alpine gardens get a second window in spring. Elsewhere in the south, a spring sowing can still flower (see Three mistakes that matter). Each sowing flowers for only a month or two, so sow a small batch every three weeks for a longer display.

Where winters are cold, sow early in the autumn window so seedlings are established before the coldest weeks. Where frosts are hard, a cloche or cold frame helps young plants through winter.

Site, soil and setup

Choose full sun, ideally six hours a day, although plants tolerate part shade. Where the hot westerly sun hits in the afternoon, a spot shaded from it helps plants through heatwaves. Love-in-a-mist grows in most soils that drain freely, does not need rich ground, and suits a pH of about 6.0 to 8.0.

For rotation, avoid a bed where seedlings damped off (rotted at the base and collapsed) last season. The fungi responsible survive between crops on plant debris.

Container growing

Pots work well if seed is sown straight into the pot where it will flower. Use a pot of at least 10 L, about 30 cm across, filled with fresh, good quality potting mix. For a pot, choose 'Persian Jewels Mixed', at about 45 cm, or a 'Miss Jekyll' variety, which can stay as low as 30 cm.

• Watering: pots dry out faster than beds, so check them often in warm weather. Water at the base once the top few centimetres feel dry.
• Feeding: from the first true leaves until flowering, water in fish and seaweed blend at 25 mL per 9 L every fortnight.
• Position: full sun, moved into afternoon shade on hot days.

Sowing Seeds

Sow direct where plants will flower (see Three mistakes that matter), or under cover only in plantable pots.

Sowing direct

• Rake the soil to a fine crumb, then sow thinly 3 mm deep, or scatter the seed and rake it in lightly.
• Keep the soil damp but never soggy; seedlings usually appear in 1 to 2 weeks, and can take up to 4 weeks.
• Thin seedlings while they are small, leaving one plant about every 30 cm.
• Guard young seedlings against snails at night (see Pests and diseases).

Starting under cover

• Sow into small plantable pots or cells of seed raising mix, 3 mm deep, 4 to 6 weeks before planting out.
• Plant out once seedlings have true leaves and stand 5 to 10 cm tall, before roots circle the pot.
• Harden off seedlings first (moving them outdoors for longer each day over about a week, so they adjust to sun and wind).
• Set each root ball in whole, without teasing the roots, and water it in.

The five varieties differ mainly in colour, height and pod shape, so choose by the flower and the pod you want.

Care by growth stage

Love-in-a-mist asks for little feeding. Steady moisture while young and free drainage matter more than fertiliser. Weeks count from sowing.

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

Deadheading lengthens flowering but removes the pods, so decide which you want from each plant.

• For flowers: every few days, snip each fading flower off at its stem.
• For pods: leave the flowers on, and let the pods swell and firm on the plant.
• For both: deadhead half the patch and leave the other half to pod.
• To limit self-sown seedlings: cut pods before they dry and split.
• To save seed: leave a few pods until they turn brown and papery. Shake the seed into a paper bag and keep it cool and dry.
• At the end: pull spent plants once flowering stops, as an annual does not flower again.

Companion planting

Love-in-a-mist suits a cottage bed and a plot of flowers grown for drying, and its flowers draw bees.

Grows well with

• Cornflower: a cool-season annual sown in the same months, for cutting and drying.
• Strawflowers: with the pods, they fill a bed grown for dried arrangements.
• Silver-leaved plants such as lamb's ear: their grey foliage sets off the fine green leaves.

Keep apart

• Low seedlings of other flowers or vegetables: self-sown love-in-a-mist can crowd them out.
• Tall, dense plants on the north side: they shade a flower that needs full sun.

Harvesting Blooms

Cut flowers when they are almost fully open, before the petals drop, and cut pods once they have formed, or once firm for drying.

• Cut with sharp snips or secateurs, taking the longest stem you can.
• Strip leaves from the lower stem, because stems last longer that way, and stand them in clean water straight away.
• For fresh pods, cut once they have begun to swell.
• For dried pods, cut when they feel firm but the stripes still show.

Hang pod stems upside down in small bunches in a dry, dark, airy place, with a paper bag over each to catch loose seed. Small batches dry faster than one large bundle. Use the flowers fresh, and the pods fresh or dried in arrangements.

Common problems

Seed fails to come up. Warm soil above about 20°C, a seed bed that dried out, or seed buried deeper than 3 mm are the usual causes. Read more

Flowering ends after a few weeks. Heat shortens an already brief bloom, so the staggered sowings in When to plant carry the display.

Plenty of flowers but no pods. Regular deadheading removes every flower before it can set a pod.

A carpet of seedlings the next season. Pods left to split scatter seed widely, and love-in-a-mist self-sows readily.

Pests and diseases

Few pests trouble love-in-a-mist, and most damage falls on seedlings and soft new growth.

Common garden snail (Cornu aspersum). It and the grey field slug (Deroceras reticulatum) feed at night in cool, moist weather and can eat seedlings to the ground. Read more

Aphids (family Aphididae). These sap-suckers cluster on soft new growth, which can become distorted and sticky with honeydew. Read more

Damping off (Pythium species and Rhizoctonia solani). Seedlings rot at the base and collapse, most often in wet soil. Read more

Prevention first

• Sow thinly and thin early, so air moves between the seedlings.
• Keep the seed bed damp but not wet.
• Clear boards, empty pots and weeds where snails shelter near young plants.
• Check shoot tips each week and hose off or squash aphids at the first sighting.

Tips

1. Love-in-a-mist has naturalised in Victoria, South Australia, New South Wales and the ACT. Near bushland, cut pods early (see Deadheading) and check your council's advice.
2. The kitchen spice sold as nigella or kalonji is black cumin (Nigella sativa), a different species. Do not use love-in-a-mist seed in its place.
3. Broadcast seed in loose drifts between perennials rather than in rows, and the fine foliage fills gaps in the border before later plants grow.