How to Grow Spring Star Flowers in Australia

Spring star (Ipheion uniflorum) is a small bulb from Argentina and Uruguay and a relative of onions in the family Amaryllidaceae. It is grown for starry, sweetly scented flowers in late winter and spring. Some botanists place it in a neighbouring genus as Tristagma uniflorum, so labels vary. It shrugs off frost and dry summers and spreads into clumps under trees and along paths. That same vigour has let it escape into bushland in parts of southern Australia.

Three mistakes that matter

1. Cutting the leaves while they are green. The grassy leaves feed the bulb for next year, so mowing or tidying them early leaves weaker bulbs and fewer flowers. Wait until the leaves turn yellow and collapse before you clear them.
2. Planting in soil that stays wet. Bulbs sitting in soggy ground, above all over summer while they rest, can rot. Choose a spot that drains freely, use a raised bed or a pot on heavy clay, and leave summer irrigation off the patch.
3. Letting it seed beyond the garden. Spring star has gone wild near Perth, Sydney and Dubbo, and in two South Australian reserves. Snip spent flowers before the seed pods ripen, bin spare bulbs and old potting mix, and keep plantings away from bushland.

When to plant

Plant dormant bulbs in autumn, from March to May, once the summer heat has broken and nights are cooling. In most southern gardens Anzac Day falls inside the window. Leaves appear in autumn and the flowers follow from late winter, so one planting is enough: the bulbs stay in the ground for years.

Bulbs that arrive during a late hot spell can wait a week or two, stored as under Harvesting Blooms. Subtropical gardeners chill them first, as under Planting Bulbs.

Site, soil and setup

Spring star is unfussy about soil type, provided water does not sit around the bulbs.

Weed status, state by state

Spring star is declared a weed in no state or territory. It is regarded as an emerging environmental weed in Victoria and Western Australia, and it spreads by seed, offsets, water and moved soil.

Never tip old potting mix or garden prunings into bushland or a creek line.

Container growing

Spring star suits shallow pots and troughs, and in wet-summer districts a pot lets you move the resting bulbs out of the rain. Choose a pot at least 20 cm across with drainage holes, holding about 4 L or more. Fill it with premium potting mix with a few handfuls of coarse grit through it. Plant at the same depth and spacing as in the ground.

The store sells two forms, both about 15 to 20 cm tall: 'Light Blue', with pale violet-blue stars, and 'Moonlights', with pure white ones. They grow the same way, so the choice is colour.

• Watering. Soak the mix after planting, then water whenever the surface feels dry while the leaves are green. Let the pot dry out once the leaves yellow.
• Feeding. Give seaweed solution at 30 mL per 9 L fortnightly through leaf growth. From the first flowers until the leaves fade, switch to liquid potash at its label rate, also fortnightly.
• Position. Sun or light shade from autumn to spring, then a dry corner, such as under the eaves, for summer.

Planting Bulbs

Spring star starts from small dormant bulbs.

Chilling

Spring star is far less demanding than tulips, and it naturalises unaided around Sydney. In subtropical gardens, though, a spell of cold before planting can bring the flowers on sooner. Put the bulbs in a paper bag in the crisper of the fridge for 6 to 8 weeks, then plant them in April or May. Gardeners in cooler zones can skip this step.

Planting in the ground

1. Ready the bed with compost and bone meal, as the table under Site, soil and setup sets out.
2. Sort the bulbs, setting aside any that are soft, mouldy or shrivelled.
3. Set each bulb pointed end up, about 5 cm deep.
4. Space them 5 to 7 cm apart, in groups of 10 to 15 or more for a drift.
5. Water in well, then keep the soil lightly moist as the leaves appear.
6. Mark the spot, since the bed looks empty all summer and is easy to dig into by mistake.

Dividing clumps

Each bulb builds a cluster of offsets (small bulbs that form beside the parent), so clumps thicken readily. When flowering thins out from crowding, lift the clump once the leaves have died down. Separate the bulbs and replant them straight away at the same depth.

Care by growth stage

Flowers depend on moisture while the leaves are green, sun, and a dry summer rest. Feed lightly.

Each autumn, spread a 5 cm layer of compost over established clumps before the leaves emerge. If growth stalls in poor soil, a light dose of all-purpose controlled release granular (NPK around 14-5-10) scratched into the surface in autumn can help.

Companion planting

Good neighbours flower at the same time, want the same dry summer, or hide the fading leaves.

Grows well with

• Daffodils and jonquils, spring bulbs that rest through the same dry summer.
• Anemones, which flower alongside and add stronger colour to a pale drift.
• Scilla, another small blue bulb that suits the same edging and pots.
• Violas, low cool-season bedding that fills the gaps between clumps.

Keep apart

• Onions, chives and garlic, whose grassy leaves and smell are easy to mix up with spring star.
• Dahlias and other thirsty summer growers, whose watering soaks the resting bulbs.
• Boundaries with bushland, a creek line or a paddock, which seed and loose bulbs can reach.

Harvesting Blooms

Pick stems whose flowers have just opened, while the clump is in full bloom.

• Pick in the morning, while it is cool and the stems are full of water.
• Snip with clean, sharp scissors or secateurs and stand the stems in water straight away.
• Take the flower stems only, and leave every leaf on the plant.

Spare or newly bought bulbs keep best dry, in a paper bag in a cool, airy cupboard, until autumn planting. A handful of stems makes a small posy for an egg cup or bud vase.

Common problems

Leaves but few flowers. Crowded clumps, deep shade or leaves cut while green can leave bulbs too weak to bloom; divide as under Planting Bulbs.

The plants vanished in summer. This is normal dormancy, and the bulbs are resting below ground until the autumn shoots appear.

Stray plants beyond the bed. Seed or moved soil is the cause. Dig out each stray, bulb and all, while its leaves still show, and put it in the rubbish.

Pests and diseases

Spring star has no significant pest problems, and most trouble comes from wet soil or damp nights.

Garden snail (Cornu aspersum). Widespread in Australian gardens, snails may graze the tender leaves and flowers on damp nights. Hand-pick them by torchlight. Read more

Grey field slug (Deroceras reticulatum). A pest across the wetter south, it feeds at night and may rasp holes in new leaves after rain. Lay a tile or flowerpot base on damp soil as a trap, and clear the slugs sheltering under it each morning. Where traps are not enough, scatter an iron-based slug bait at the label rate as the leaves emerge. Read more

Bulb rot (soil fungi such as Fusarium). Bulbs kept wet turn soft and fail to shoot in autumn. Discard soft bulbs and replant firm ones where the soil drains.

Prevention first

• Plant only firm, plump bulbs, and throw out any soft ones found at lifting.
• Leave ground beetles, spiders and earwigs be, since they help keep slug numbers down.
• Check for snails and slugs on damp evenings while the leaves are young.
• Rake away dead leaves once the clump goes dormant, removing daytime shelter for slugs.

Tips

1. Plant a pot by the front door, where the scent and the starry flowers can be seen up close.
2. The flowers close at night, so put drifts where you pass during the day.
3. Edge a lawn with spring star only where mowing can wait until the leaves have yellowed.

Due to quarantine restrictions and our shipping policy, we cannot send spring star bulbs to Western Australia or Tasmania.