Watsonia borbonica aka Bugle Lily

Watsonia borbonica is a tough, easy-to-grow plant that requires minimal attention once established. It thrives in full sun with well-drained soil and has no serious pest or disease problems. The main consideration is managing its dormancy — in cold climates (below USDA zone 8), corms need to be lifted and stored dry over winter. In suitable climates, it will flower reliably year after year with very little intervention.

Watsonia borbonica reaches 1–1.5 metres tall in cultivation, with flower spikes up to 2 metres in ideal conditions. The clump spreads to about 30–50 cm wide. It grows at a moderate rate, reaching its full size within 2–5 years from corms. Seedlings take 2–3 years to reach flowering size. The plant forms upright fans of sword-shaped leaves and produces branching flower spikes that can carry 20 or more blooms.

Watsonia borbonica is native to the southwestern Cape Province of South Africa, found from Tulbagh southwards to the Cape Peninsula and eastwards to Bredasdorp. It grows naturally on rocky sandstone slopes, well-drained clay and granite slopes, and occasionally in deep sandy soil at the base of mountains. This is a winter-rainfall region with hot, dry summers — the plant has adapted by growing actively during the cooler, wetter months and going dormant in summer.

Watsonia borbonica produces spectacular spikes of large, tubular flowers in late spring to early summer, blooming for 4–5 weeks. Flowers are pale to deep pink or light purple with darker midlines and white streaks at the base, and are faintly fragrant. Each branching spike carries up to 20 flowers on the main axis and up to 10 on side branches. White-flowered forms exist, particularly in subspecies ardernei. In its native South African habitat, the plant flowers most prolifically in the first and second years after fire.

Watsonia borbonica is primarily pollinated by large solitary bees of the family Apidae (subfamily Anthophorinae). The bees visit early in the morning to collect pollen from freshly opened flowers. On the second day of flowering, the styles unfurl as receptivity peaks and nectar levels rise. By noon, both pollen and nectar are depleted. Sunbirds and long-tongued flies also visit the flowers but are considered secondary visitors rather than primary pollinators.

The easiest method is division of corm offsets during the dormant season (summer). Lift the clumps, separate the daughter corms, and replant in autumn at a depth of 40–60 mm in well-drained soil. Divided corms flower within a few months. For seed propagation, sow in autumn in deep trays (minimum 10 cm) with a mix of 2 parts sand, 2 parts compost, and 1 part loam. Cover seeds 3–4 mm deep, keep moist and lightly shaded. Germination takes 3–4 weeks, but seedlings take 2–3 years to first flower.

Watsonia borbonica has a distinct seasonal cycle that reverses the typical growing pattern. It grows actively from autumn through spring, then goes completely dormant in summer. During the growing season, keep the soil moist and feed occasionally with potash-rich fertilizer. When foliage yellows and dies back after flowering in late spring/early summer, stop watering entirely and allow the corms to rest dry.

Watsonia borbonica is half-hardy and can withstand mild winter frosts down to approximately -5°C (23°F). It is rated RHS H3 and USDA zones 8–10. In colder regions, protect corms with a deep dry mulch in winter, or lift and store them in a frost-free location. The plant originates from the winter-rainfall region of South Africa's Western Cape, where winters are cool and wet and summers are hot and dry.

Watsonia borbonica is not particularly humidity-sensitive. It originates from the Mediterranean-climate Western Cape of South Africa, where conditions range from moist winter air to dry summer heat. Good air circulation is more important than humidity levels — the plant is susceptible to rot if conditions are too damp during its summer dormancy. In cultivation, average outdoor humidity is fine and no supplemental humidity is needed.

Watsonia borbonica is primarily an outdoor plant, hardy in USDA zones 8–10. It thrives in full sun with well-drained soil in a warm, sheltered position. In colder zones, treat it like gladiolus — plant corms in spring, enjoy the blooms, then lift and store the corms frost-free over winter. In mild climates, leave corms in the ground year-round and they will naturalize, forming larger clumps over time. Divide every 3–5 years to prevent overcrowding.

Watsonia borbonica requires minimal pruning. After flowering is complete, cut back the spent flower stems and yellowing foliage as the plant enters summer dormancy. RHS notes that no formal pruning is needed. The purplish stems and seed capsules can be left for decorative interest if desired. Every 3–5 years, lift and divide overcrowded clumps during the dormant season to maintain vigorous flowering.

Watsonia borbonica has a faint, pleasant fragrance. SANBI describes the flowers as 'faintly fragrant,' and Missouri Botanical Garden notes the flowers are 'fragrant.' The scent is subtle rather than strong — you may need to be close to the flowers to appreciate it. It is not a plant typically grown for its fragrance, but the gentle scent is a nice bonus when cutting flowers for arrangements.

Watsonia borbonica has two recognized subspecies. Subspecies borbonica is the typical form with pink to light purple flowers and downward-bent stamens. Subspecies ardernei is best known for its white-flowered form, widely cultivated and named after H.M. Arderne of the Arderne Gardens in Cape Town — though in the wild it also occurs with pink flowers in the Paarl to Breede River Valley area. The white ardernei form is the most popular cultivar in gardens.

Watsonia borbonica has no serious pest or disease problems. RHS describes it as generally pest-free and disease-free. Missouri Botanical Garden confirms no significant insect or disease issues. The main concern is mealy bug infestation on stored corms during the dormancy period — SANBI recommends storing lifted corms in cool, dry conditions to prevent this. Good drainage is essential to prevent corm rot, particularly during the summer dormancy when the corms should be kept dry.

Bugle Lily should be watered regularly, allowing the soil to dry out between waterings.

Bugle Lily loves a well-draining soil. Perlite and vermiculite help with drainage, while coco coir adds organic matter, so a good potting soil mix will have all three. You can improve store-bought soil by adding some perlite to it.

Bugle Lily requires abundant, bright, and direct light to thrive. The best placement for this plant is within one foot of a window to ensure it receives enough light. If you live in an area with more extreme weather, such as hot summers or cold winters, you may need to adjust the placement of the plant accordingly. During hot summer months, it is important to place the plant away from full sun, as this can cause the leaves to yellow or burn. During cold winter months, it is best to move the plant closer to the window to take advantage of the extra light that can help it survive. By keeping an eye on the current weather in your area, you can make sure your Pink Watsonia is always in the right place to thrive.

Once the Bugle Lily has doubled in size or after a year has passed, it should be moved to a new pot. By replacing the soil with fresh potting soil containing all the vital nutrients, your plant will receive all the sustenance it needs, negating the requirement for fertilizer. It's important to remember that plants get their energy from the sun, not fertilizer.

No verified data on the toxicity of this plant exists within Ploi's records. Should you, someone in your family, or your pet ingest plant material with an unknown toxicity level, it is recommended to seek medical advice.