Galtonia candicans: expert tips for growing summer hyacinths

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Galtonia candicans brings a cool, elegant note to the late-summer border, sending up metre-tall spires hung with waxy, pure white bells that nod gently in the breeze. Sometimes called the summer hyacinth, it flowers from midsummer into early autumn, precisely when many perennials are beginning to tire. Its greatest charm is the way those luminous white flowers glow at dusk, lightly scented and perfectly at home among grasses, dahlias and late salvias.

Growing conditions

Give Galtonia candicans the sunniest spot you can spare. A full day of sun produces sturdy, upright stems, whilst shade encourages floppy growth that leans towards the light. A sheltered position matters too, since the tall flower spikes catch the wind badly in exposed gardens.

Soil should be deep, fertile and rich in organic matter, yet free-draining enough that the bulbs never sit in cold, stagnant wet. A neutral to slightly acidic pH suits it best, though it grows perfectly well on mildly alkaline ground. Heavy clay is the main enemy: winter waterlogging rots the bulbs far more reliably than frost kills them.

Native to the damp summer grasslands of the Drakensberg in South Africa, it enjoys moisture whilst in growth and dryness when dormant. In mild coastal and southern gardens it can stay in the ground year-round; in colder inland areas, lift the bulbs or mulch generously.

How to plant Galtonia

Plant bulbs in spring, from March to early May, once the worst of the winter wet has passed. Autumn planting is possible only in mild, very well-drained gardens.

• Spacing: set bulbs 20–30 cm apart, in groups of five to seven — clustered planting looks far more natural than a line, and the stems support one another.
• Depth: plant 15–20 cm deep, with the pointed nose upwards; deeper planting anchors the tall stems and gives extra frost protection.
• Soil preparation: fork in well-rotted compost or leaf mould, plus a bucket of horticultural grit per square metre on heavier soils.
• Watering in: water thoroughly after planting to settle the soil, then keep just moist until shoots appear in six to eight weeks.
• Propagation: lift established clumps when dormant and detach the offsets forming around the parent bulb; seed also works, but expect three to four years to flowering.

Care through the seasons

Spring: Strap-shaped grey-green leaves push through from April onwards, later than many bulbs, so mark the position to avoid accidental digging. Apply a balanced general fertiliser or a mulch of garden compost as growth begins. Watch for slugs, which adore the soft emerging foliage.

Summer: This is the plant’s active season and it is thirstier than most bulbs — water deeply in dry spells, especially as the flower spikes extend. A high-potash feed such as tomato fertiliser every fortnight from June improves flower size and count. Stake individually in windy gardens, and remove faded spikes unless you want seed.

Autumn: Allow the foliage to yellow naturally so the bulb can recharge, then cut it away at ground level. In mild regions, cover the crown with 10–15 cm of dry mulch — bark, bracken or straw. In colder gardens, lift the bulbs in October, dry them off and store in barely damp sand somewhere frost-free.

Winter: The plant is fully dormant and disappears completely below ground. Its chief need is dryness: excess winter moisture, rather than cold alone, causes most losses.

Best varieties to grow

The genus is small, so the choice runs to a handful of species and one or two named selections — all worth growing.

• Galtonia candicans — the classic species, holds an RHS Award of Garden Merit for its pure white, green-throated bells on metre-high stems.
• Galtonia candicans ‘Moonbeam’ — a softer form with creamy, faintly green-tinged flowers that blend beautifully with silver foliage.
• Galtonia viridiflora — shorter at around 70 cm, with cool pale-green bells and broader, glaucous leaves; slightly more drought-tolerant.
• Galtonia princeps — earlier flowering, from late June, with greenish-white bells held in a denser, more compact spike.

Pests, diseases and common problems

• Slugs and snails: ragged holes in young leaves and chewed flower stems, worst in April and May. Use wildlife-safe ferric phosphate pellets, wool pellets or evening hand-picking around the emerging shoots.
• Bulb rot: shoots that fail to appear, or soft, foul-smelling bulbs when lifted, caused by cold waterlogged soil. Improve drainage with grit, plant on a slight mound and lift bulbs in wet-winter gardens.
• Flopping stems: spikes that lean or snap after summer storms, usually a sign of too much shade, over-rich nitrogen feeding or an exposed site. Plant deeper, feed with potash rather than nitrogen, and provide discreet ring supports early in the season.