Lachenalia contaminata

Lachenalia contaminata

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At a Glance

Quick Answer: Lachenalia contaminata is a small winter-growing bulb from the Western Cape of South Africa, best grown in the UK as a pot plant in a cool greenhouse, conservatory or bright, frost-free windowsill. Plant the bulbs in early autumn in sharply drained compost, water through the growing season, then keep the pots dry during summer dormancy.

Overview

Lachenalia contaminata is a small, bulbous perennial in the asparagus family, native to the winter-rainfall region of the Western Cape, South Africa. It grows in damp, sandy or peaty lowland flats there, putting out leaves in autumn and flowering through winter and spring before retreating underground for a hot, dry summer rest. The plant is closely related to the better-known Cape cowslip (Lachenalia aloides) and the similar Lachenalia orthopetala, but it is a more delicate species with white, bell-shaped flowers lightly marked in brown or red.

In the UK, L. contaminata acts as a winter-interest bulb for a frost-free greenhouse, conservatory or bright unheated windowsill. Strictly speaking it is not reliably hardy outdoors anywhere except the mildest coastal gardens of south-west England and the Channel Islands, where drainage and a sheltered rain-shadow can be provided. Elsewhere, treat it as a container bulb that is brought under cover before any hard frost and kept dry through summer.

Appearance

The flowers are small, bell-shaped and pendulous, carried on short stalks (shortly pedicellate) in a loose raceme. They are predominantly white, with brown, red or maroon markings on the outer segments that give the species its name: contaminata, meaning "stained" or "blemished", a reference to those coloured tips. A mature bulb typically produces a single flower spike around 15–25 cm tall, with up to a dozen blooms opening in succession.

Foliage is part of the show. Each bulb sends up two leaves, usually broad and strap-shaped, sometimes lightly banded or spotted. The leaves emerge before or alongside the flower spike and remain green for several weeks after flowering finishes, replenishing the bulb for the following season. Growth is compact, making the plant suitable for a windowsill collection, an alpine house or the front of a display bench.

The flowering season in UK cultivation is late winter into spring, generally from March through May, depending on when the bulbs were started into growth and how cool the glasshouse has been kept. Cool conditions prolong the display; a hot, dry atmosphere shortens it.

Growing Conditions

Light is the first consideration. Lachenalia contaminata wants the brightest position available: full sun outdoors in winter, or the lightest bench in a cool greenhouse. A dim, warm room produces stretched leaves and few flowers. Turn pots every week or two to keep growth even.

Drainage is more important than rich soil. Use a peat-free bulb compost amended with about a third by volume of horticultural grit, or a mix of two parts loam-based John Innes No. 2, one part grit and one part leafmould. The container must have a drainage hole, and it should be wide enough to take several bulbs spaced a few centimetres apart. Stand the pot on grit or pot feet so excess water drains freely.

Temperature should be cool, not tropical. In active growth, daytime temperatures of 7–15 °C suit the plant well, with nights a few degrees lower. In mild, sheltered southern gardens, plunged pots can spend autumn and early winter outside in a rain-shadow before being brought under cover for the coldest weeks. In the rest of the UK, an unheated greenhouse, a frost-free conservatory or a bright shed with a small heater set to 5 °C is ideal.

Water follows growth. From the time new shoots appear in autumn, water thoroughly and then wait until the surface of the compost has begun to dry before watering again. During active growth the compost should be lightly moist but never saturated. After flowering, taper watering as the leaves yellow, and stop altogether once the plant is fully dormant. Do not water dormant bulbs simply because the compost looks dry: summer dryness is normal and necessary.

Air movement matters. A stagnant, warm greenhouse encourages aphids and soft growth. Open vents on mild days in autumn and spring, and avoid placing pots near a radiator or in a hot kitchen.

Planting and Care

Pot the bulbs in September or October, before the main winter growth begins. Plant them with their necks just below or level with the compost surface; deep planting in a poorly drained mix increases the risk of rot. Several bulbs can share a wide, shallow pan, and each container should be labelled because dormant bulbs are difficult to tell apart.

1. Select a clean pot with drainage holes and a layer of crocks or coarse grit at the base.
2. Half-fill with gritty bulb compost.
3. Position the bulbs with the growing tip uppermost, spaced 3–5 cm apart.
4. Top up with compost so the neck of each bulb is at or just below the surface.
5. Water once to settle the compost, then leave on a bright, cool bench.
6. Water again only when the surface begins to dry; rainwater is ideal.
7. Feed every three or four weeks during active growth with a half-strength, high-potash liquid fertiliser such as a tomato feed.
8. Deadhead spent flowers if you do not want the bulb's energy used up in seed.
9. Allow the leaves to yellow and wither naturally in late spring.
10. Move the pot to a dry, airy, shaded place and keep it dry until growth resumes the following autumn.

Feeding is supplementary rather than essential. A fresh, loam-based compost holds enough nutrients for a single season, and over-feeding produces soft foliage at the expense of sturdy flower spikes. Always water the compost before applying liquid feed, and never leave the pot standing in a saucer.

Pruning is not required. Remove only the dead flower stem and any leaves that have dried or yellowed completely. Cutting green leaves prematurely weakens the bulb and can reduce flowering in the following winter.

Propagation is most easily done by offsets. Lift the dormant clumps in summer, gently separate well-developed bulblets and pot them up individually in small pots of gritty compost. Keep them barely moist until new growth begins in autumn. Seed is possible for species, but seedlings take two to three years to reach flowering size and named selections do not come true.

Seasonal care follows a simple cycle. From September to November, repot if needed and resume watering. From December to March, provide maximum light, careful watering and cool ventilation. After flowering, continue to feed briefly while the leaves remain green. By late May or June, ease off and store the dormant pots somewhere dry, airy and shaded, checking occasionally for rot or shrivelling but not watering them.

Common Problems

Bulb rot

Symptom: bulbs fail to sprout, become soft, or collapse at the base. Cause: waterlogged compost, poor drainage, or watering during dormancy. Fix: discard affected material, replace the compost with a grittier mix, and keep dormant pots dry. A useful trick is to mix extra grit into the compost before planting rather than trying to correct drainage later.

Few or no flowers

Symptom: leaves grow but flower spikes do not appear, or only a token spike forms. Cause: insufficient winter light, too much warmth, premature removal of the previous year's foliage, or a bulb too small to flower. Fix: move the plant to the brightest, coolest spot available, use a balanced rather than nitrogen-heavy feed and leave green leaves intact after flowering. One common mistake is overwintering a pot in a warm living room where it grows leaves but never initiates a spike.

Leggy growth

Symptom: leaves and flower stems stretch and lean towards the light. Cause: inadequate light combined with warmth. Fix: move the container to a brighter windowsill, greenhouse or conservatory, and turn it weekly. Cool nights and good ventilation help keep growth compact.

Aphids

Symptom: greenfly cluster on young leaves or flower stems, leaving sticky honeydew. Cause: soft new growth in a warm, poorly ventilated position. Fix: inspect plants weekly, squash small colonies or rinse them off with water, and improve ventilation. Avoid unnecessary insecticide on a small flowering display, especially where bees and other beneficial insects can reach it.

Slugs and snails

Symptom: ragged leaves or missing flower stems, particularly on pots placed outside. Cause: feeding at night in damp UK weather. Fix: raise containers on pot feet, inspect after dusk and remove hiding places. A simple trick is to keep the pot on a clean, dry stand rather than directly on paving where pests shelter.

Virus-like mottling

Symptom: persistent distorted growth or irregular streaking that does not match the natural markings of the variety. Cause: possible virus infection, which can spread through sap and handling. Fix: isolate and dispose of badly affected plants; do not propagate from them. Because symptoms overlap with natural leaf patterning, seek specialist advice before discarding a valuable specimen.

Popular Varieties

Lachenalia contaminata is itself a species rather than a cultivar group, and named selections are limited. The following are forms or close relatives that are most likely to be encountered in UK specialist bulb lists.

• Lachenalia contaminata (species). The typical form, with white, bell-shaped flowers marked in brown or red, as described above. Widest availability and the safest choice for a first pot.
• Lachenalia orthopetala. Closely related to L. contaminata and found in the same habitat, with similar white to purple flowers. Useful for extending a small collection and often crossed or confused with it in older lists.
• Lachenalia aloides (and var. quadricolor). The vigorous, orange and yellow Cape cowslip, much easier to obtain and a useful comparison for anyone new to winter-growing South African bulbs.
• Lachenalia rubida. A red-flowered species grown for a vivid, hot-coloured display in a cool, bright position.
• Lachenalia mutabilis. A changeable species whose flowers shift colour as they mature, offering a longer display from a single spike.

Labels matter: L. contaminata has been confused with L. orthopetala in older trade lists, and stock offered under one name may include the other. Specialist UK bulb nurseries and alpine-plant growers are more likely to offer correctly named material than general garden-centre benches.

Sources & Further Reading

• Royal Horticultural Society: Lachenalia contaminata (wild hyacinth) plant profile. Source: https://www.rhs.org.uk/plants/86707/lachenalia-contaminata/details, accessed 2026-07-23.
• Pacific Bulb Society Wiki: Lachenalia Species Two, including L. contaminata Aiton. Source: https://www.pacificbulbsociety.org/pbswiki/index.php/LachenaliaSpeciesTwo, accessed 2026-07-23.
• South African National Biodiversity Institute (SANBI): Lachenalia orthopetala (a close relative sharing the same habitat and cultivation needs). Source: https://pza.sanbi.org/lachenalia-orthopetala, accessed 2026-07-23.
• Overberg Renosterveld Conservation Trust: Lachenalias of Overberg Renosterveld. Source: https://overbergrenosterveld.org.za/lachenalias-of-overberg-renosterveld/, accessed 2026-07-23.
• Pacific Horticulture: Bulbs from South Africa (general cultivation notes relevant to the genus). Source: https://pacifichorticulture.org/articles/bulbs-south-africa/, accessed 2026-07-23.
• BBC Gardeners' World Magazine: Container bulb basics (UK dormancy and watering practice). Source: https://www.gardenersworld.com/how-to/grow-plants/growing-bulbs-in-pots/, accessed 2026-07-23.

Pests and Diseases

For step-by-step help, read Dealing with Slugs and Snails and Treating Powdery Mildew. Or browse the full plant problem solver to diagnose an issue by symptom.