How to Grow Kniphofia in Australia

Red hot pokers (Kniphofia), also called torch lilies, are clump-forming perennials in the family Asphodelaceae. They are grown for tall spikes of tubular flowers in red, orange and yellow. They come from southern Africa, shrug off drought, frost and wind once settled, and draw wattlebirds and other nectar-feeding birds into Australian gardens. Most failures trace back to one thing: soil that stays wet around the crown in winter.

Three mistakes that matter

1. Heavy, wet soil. Roots and crowns sitting in cold, waterlogged ground through winter can rot, and the clump dies out. Plant in free-draining soil, or raise heavy clay into a mound with coarse grit, as set out under Site, soil and setup.
2. Burying the crown. A crown set deeper than it grew, or smothered under mulch, stays wet and is prone to rot. Plant a potted crown at the depth it sat in its pot, and keep mulch clear of it.
3. Dividing too soon. Red hot pokers resent disturbance, and a freshly split clump can take a year to settle and flower poorly. Leave clumps alone for several years, and divide only once flowering falls off from crowding.

When to plant

Plant in spring as the soil warms and the worst of the winter wet has passed. The crown then has a full growing season to root in. Where winters are mild and soils drain freely, autumn planting around Anzac Day also works, because the roots settle in cool, moist soil before summer.

A late planting needs regular deep soaks through its first summer. Where frost meets cold, wet winter soil, skip autumn and wait for spring, because a new crown there is the one most likely to rot.

Site, soil and setup

Sun and drainage decide how well a clump flowers. Red hot pokers take sandy, loamy or gravelly soils, and coastal wind, but not ground that stays soggy.

A clump stays put for years, so rotation does not apply. Where water pools after storms, read waterlogged soil before planting.

Weed status, state by state

Red hot poker (Kniphofia uvaria), the species both store lines belong to, has escaped from gardens in south-eastern Australia. It is an environmental weed in Victoria and New South Wales, though no state or territory declares it.

It spreads by creeping rhizomes (underground stems) and by small wind-blown seed. Keep plantings well away from bushland, swamps and creeks, and cut spent spikes before seed ripens. Dig out shoots creeping beyond the clump, and bin unwanted divisions: dumped garden waste has started roadside clumps that last for years.

Container growing

Dwarf types under about 60 cm, such as 'Little Maid', suit pots best. Give them a pot at least 25 cm wide, about 7 L, with drainage holes. Taller plants like the store's lines need a pot at least 40 cm wide and deep, about 30 L. Fill with premium potting mix blended with coarse grit, roughly seven parts to three.

• Watering. Water when the mix is dry a few centimetres down, more often in hot weather. See watering pots in summer.
• Feeding. Water in fish and seaweed blend at 25 mL per 9 L every fortnight from spring to late summer. Nutrients in potting mix soon run out.
• Position. Full sun. In cold, wet winters, move the pot against a sheltered wall and raise it on feet so it drains.

Planting Crowns

Red hot pokers are started from a crown: a potted plant, a bare-root side shoot or a division from an established clump.

Crown division

Lift a crowded clump with a fork in spring, or in autumn where winters are mild. Split it into pieces that each carry a fan of leaves and plenty of roots. Or slice off a side shoot without lifting the whole clump. Dig compost into the bed before replanting. Expect fewer flowers that first year; divisions usually flower within one or two years. See dividing perennials for the method.

Planting a crown

1. Prepare the bed as under Site, soil and setup.
2. Set a potted plant at the same depth it grew in its pot. Plant a bare-root crown with its top shoot just above the soil.
3. Space plants 60 to 90 cm apart, closer for dwarf types.
4. Firm the soil and water in with seaweed solution at 30 mL per 9 L.
5. Mulch around, not over, the crown.

From seed

Seedlings vary because red hot pokers cross readily, so seed will not reproduce a named variety such as 'Mango'. Collect seed in autumn, keep it in the fridge, and sow it in spring in trays kept near 15°C. Press it onto moist seed-raising mix without covering it, because it needs light to germinate, and allow up to 90 days. Plants take about three years to flower.

Care by growth stage

Water matters most in the first year; after that, drainage and a little restraint keep clumps flowering. Established plants are not hungry and need little feeding in fair soil.

Before watering an established clump, check the soil is dry about 15 cm down. If growth stalls in very poor sand, a light dose of all-purpose controlled release granular (NPK around 14-5-10) scratched in each spring can help.

Cutting Back

Most of the work is removing spent spikes and old leaves, which keeps the clump tidy and stops seed spreading. Do the leaf work in late winter or early spring, once the coldest, wettest weather is over.

• Cut each faded flower stem right down at the base, which also leaves room for new spikes.
• On evergreen clumps, gently pull out dead or tatty leaves one at a time in spring.
• Pull green leaves out at the base rather than cutting them, so no stubs are left.
• Where a clump dies back over winter, leave the old leaves on to shelter the crown, then cut them off at the base in spring.
• In the coldest districts, tie the leaves together over the crown in winter to shed rain.
• Wear gloves, because old leaves can be slimy and the edges are finely toothed.

Companion planting

Pair red hot pokers with plants that like the same sun and sharp drainage.

Grows well with

• Salvia, whose blue and purple flowers set off the warm spikes.
• Rudbeckia and cannas, for a bed of hot colours.
• Ornamental grasses, which share the dry, sunny conditions and soften the clumps.

Keep apart

• Thirsty, moisture-loving plants, whose watering keeps the crowns too wet.
• Large shrubs and trees, whose shade cuts flowering.

Harvesting Blooms

The store's lines flower mainly from summer into autumn, though some other kniphofias flower from autumn to spring. The small flowers open from the bottom of the spike upwards. Cut a stem when the lowest flowers have opened and the top is still in bud.

• Cut in the cool of early morning, at the base of the stem.
• Leave plenty of spikes on the plant for the birds.

Bare-root crowns and divisions do not store: plant or pot them up straight away.

Common problems

Leaves but few flowers. Too much shade, a crowded clump that needs dividing, or a clump split recently (see Three mistakes that matter).

Clump collapsing over winter. Wet soil around the crown; see Three mistakes that matter and the root rot entry under Pests and diseases.

Flowers fading from the bottom up. This is normal: each spike opens from its base, so the older lower flowers fade first.

Seedlings appearing away from the clump. Spikes were left to set seed, which spreads on the wind; cut them sooner and pull seedlings young.

Brown, tatty leaves in late winter. Old foliage dies back with the cold; tidy it in spring as under Cutting Back.

Pests and diseases

Red hot pokers rarely suffer serious pest or disease trouble, and most problems start with wet soil or a stressed clump.

Garden snail (Cornu aspersum). Snails, and slugs with them, hide among the leaves and chew emerging flower spikes. Check the clump on damp evenings, hand-pick, and use an iron-based bait if needed. Read more

Thrips, including gladiolus thrips (Thrips simplex). Tiny insects that fleck, silver and distort flowers and young leaves. Cut off badly marked spikes and spray insecticidal soap late in the day, away from feeding bees. Read more

Aphids (family Aphididae). Colonies can gather on young flower spikes, and a heavy infestation distorts the blooms. Hose them off with a firm jet of water, or cut off a badly infested spike. Read more

Root and crown rot (Phytophthora and Fusarium species). The plant wilts, and the leaves turn dull and pull out easily. There is no cure: bin affected plants and do not replant red hot pokers in that spot.

Prevention first

• Plant in full sun and free-draining soil, so clumps stay strong.
• Check young flower spikes for aphid colonies and snails as they rise.
• Clear dead leaves and litter where snails shelter.
• Check bought crowns for soft or rotten bases before planting.

Tips

1. Plant where you can see the clump from a window, because wattlebirds and rosellas visit the spikes through the flowering season.
2. In exposed coastal gardens, red hot pokers make a reliable accent, since they tolerate wind and some salt.
3. Bin seed-laden spikes rather than composting them, so seed does not spread with the compost.

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