How to Grow Crinum in Australia

Crinum lily (Crinum x powellii), also called Powell lily or swamp lily, is a large bulb in the family Amaryllidaceae. It is grown for clusters of fragrant pink or white trumpet flowers held above broad, strappy leaves through the warm months. Clumps can last for decades, and old Sydney gardens still hold plantings that have survived years of neglect. The usual mistakes are burying the bulb too deep and moving it once it has settled.

Three mistakes that matter

1. Burying the neck. A crinum bulb tapers into a long neck. Bury all of it in heavy soil and root growth suffers. Leave the top of the neck above the soil, as set out under Planting Bulbs.
2. Moving or splitting a settled clump. Crinums resent disturbance, and a lifted or divided clump can sulk for one to three seasons before it flowers again. Choose a permanent spot at planting and leave the clump alone.
3. Letting the lily caterpillar go unchecked. These caterpillars feed at night and can strip a whole clump in a few days, then bore into the bulb. Pests and diseases sets out what to look for and when.

When to plant

Plant bulbs in spring, once frosts have passed and the soil is warming, so roots settle before summer. Crinums need one to three seasons to settle before they flower freely, so the first summer may bring leaves and only a stem or two. In frost-free districts, dormant bulbs can also go in during autumn.

Dividing is the exception to spring planting: lift clumps while they are resting in winter or very early spring.

Site, soil and setup

Crinums take sun or part shade and most soils, sand to heavy clay. They cope with a couple of days of flooding but not weeks of wet soil.

A clump stays put for decades, so rotation does not apply. On ground that stays soggy, read waterlogged soil before choosing the spot.

The two crinums in the range

Both listings are forms of the same old hybrid, Crinum x powellii. It is a garden cross between two South African species, Crinum bulbispermum and Crinum moorei.

Both are grown the same way. New plants come from offsets, because the hybrid rarely sets viable seed.

Not the native swamp lily

The name swamp lily also belongs to an Australian native, Crinum pedunculatum, which grows in coastal swamps and along streams from Jervis Bay north. It carries 10 to 40 spidery white flowers per stem, with narrow, spreading petals and red to purple stamen stalks. Powell lily carries about six to ten wide pink or white trumpets per stem.

Weed status, state by state

Powell lily is not a declared weed in any state or territory, though one of its parents has escaped from gardens in two states.

Keep plantings back from bushland and creeks, where escaped crinum clumps have appeared downhill of gardens.

Container growing

Choose a pot about 5 cm wider than the bulb, because crinums like to be a little pot-bound. For a large bulb that usually means one at least 30 cm wide and deep, about 20 L, with drainage holes. Fill it with premium potting mix and set the bulb with its neck showing above the mix.

• Watering. Keep the mix moist in spring and summer, then let it dry between waterings once flowering ends. See watering pots in summer.
• Feeding. Water in fish and seaweed blend at 25 mL per 9 L every fortnight from spring until flowering ends.
• Position. Sun to part shade, out of strong wind. Where frosts are hard, move the pot to a frost-free spot before winter.

Planting Bulbs

Crinums are planted as dormant bulbs, often sent bare-rooted with the leaves and roots trimmed, and they handle this well.

Planting a bulb

1. Prepare the bed as under Site, soil and setup, and wear gloves (see the caution under Harvesting Blooms).
2. Dig a hole deep enough to take the round body of the bulb.
3. Shake any nursery potting mix off a potted bulb, then set it upright so the top of the neck sits just above soil level.
4. Space bulbs 40 to 60 cm apart, because each one builds into a wide clump.
5. Firm the soil and water in with seaweed solution at 30 mL per 9 L.
6. Keep the soil just moist until new leaves appear.

Dividing a clump

Older clumps make side bulbs, called offsets. Lift a crowded clump while it is resting, every four or five years at most. Remove an offset once its leaves are about 30 cm tall, keeping a few roots attached, and plant it like a new bulb. See dividing perennials.

Care by growth stage

Water through flowering decides the display: crinums take drought once settled, but buds dry before they open in dry soil. Feed lightly, because an established clump in fair soil needs little.

Leaves stay green all year in warm districts but can die down in cold ones, which is normal. If growth stalls in poor sand, a light dose of all-purpose controlled release granular (NPK around 14-5-10) scratched in each spring can help.

Companion planting

The big leaves need room, so pair crinums with plants that stay low or stand well clear.

Grows well with

• Low groundcovers, which set off the clump and keep weeds down around it.
• Palms and other bold-leaved plants, which crinums suit as an underplanting.
• Ornamental grasses, whose fine leaves contrast with the broad crinum foliage.

Keep apart

• Vegetable beds, because every part of the plant is poisonous if eaten.
• Clivias, hippeastrums and the native swamp lily, which share the lily caterpillar and help it spread through a bed.
• Dense shrubs that will crowd the clump and cast deep shade.

Harvesting Blooms

Cut a stem when its first buds open, and the rest of the cluster usually keeps opening in the vase.

• Cut the stem low, close to the base.
• Expect each flower to last a day or two; hot weather shortens that.
• Cut spent stems at the base once the last flower fades.
• Leave the leaves on the plant, because they feed the bulb.

Bulbs are tough out of the ground for a short time, but plant new ones soon after they arrive.

Common problems

Leaves but no flowers. A new or recently divided clump is still settling, which can take one to three seasons (see When to plant).

Soft, rotting bulb. The soil stays wet for weeks, or a bulb was planted still wrapped in its nursery potting mix; replant sound bulbs in drained soil.

Scorched, bleached leaves. Hot afternoon sun has burnt the foliage (see Site, soil and setup for shade).

Blackened leaves after frost. Frost has killed the foliage, but the bulb usually regrows in spring; mulch it heavily before the next winter.

Pests and diseases

Crinums shrug off most pests, but two caterpillars that feed mainly on the amaryllis family can kill a clump.

Lily caterpillar (Spodoptera picta). Grey caterpillars striped black, with a yellow stripe as they grow to about 5 cm, feed in groups at night and bore into the crown. Squash egg masses under the leaves, pick caterpillars off at dawn, and bin badly damaged plants.

Lily borer (Brithys crini). Black caterpillars with white spots and an orange head tunnel inside leaves and stems. They are recorded on a native crinum and other amaryllis-family plants in Queensland, New South Wales and the Northern Territory. Pick them off and cut out mined leaves.

Garden snail (Cornu aspersum). Snails, and slugs with them, chew young leaves as they unfold. Hunt them by torchlight after rain. Read more

Prevention first

• Look under the leaves for hairy egg masses each week from flowering into autumn.
• Clear dead leaves and litter from around the crown, where caterpillars pupate and snails shelter.
• Look for clear, papery windows in the leaves, where lily borer feeds inside under the leaf skin.
• Grow plants in sun and drained soil, so clumps stay strong.

Tips

1. Plant near a path or outdoor seat, because the flowers are fragrant and the white form is sweetest in the evening.
2. Plant a few bulbs in a group rather than dotting singles, so the flower stems make a show together.
3. If you share a clump with friends, take offsets from the edge rather than lifting the whole plant.

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