Plant problems

Why Are My Veltheimia Leaves Curling?

Q: Why are my veltheimia leaves curling?

Veltheimia (forest lily or sandlelie) leaves curl and yellow most commonly in UK cultivation because of overwatering during the summer dormancy period (veltheimia is a winter-growing bulb from South Africa that is actively growing from autumn to spring and is fully dormant in summer; watering during summer dormancy causes the bulbs to rot, producing yellowing and curling of the leaves when the plant re-emerges in autumn), cold damage when grown as a greenhouse or house plant (veltheimia is frost-tender and is typically grown in the UK as a cool greenhouse or conservatory plant; exposure to temperatures below about 2 to 5°C causes the attractive, glossy, strap-like leaves to curl, go limp, and develop soft, water-soaked patches), or summer overwatering causing bulb rot (the same overwatering that kills during dormancy can also cause the roots to rot even during the growing season if the soil is kept too wet without adequate drainage). Veltheimia is a small genus of just two species of winter-growing, bulbous perennials from South Africa; Veltheimia bracteata (forest lily) is the more commonly grown species in the UK, producing a basal rosette of broad, glossy, strap-like, wavy-edged leaves in autumn and then a striking, upright flower spike of densely packed, hanging, tubular flowers in pink-purple, cream, or yellow from December to March. The flowers are produced in midwinter and make veltheimia an exceptionally valuable pot plant for a cool greenhouse, conservatory, or frost-free porch, producing its flower spike when almost nothing else in the garden is in flower.

Q: Is veltheimia hardy in the UK?

Veltheimia is frost-tender and is not hardy in the UK outdoors; it is grown as a cool greenhouse or conservatory plant, or as a house plant in a cool, bright room. The minimum temperature for veltheimia is approximately 2 to 5°C; exposure to lower temperatures, particularly if the compost is wet, causes damage or death. A frost-free greenhouse, unheated conservatory, or cool porch that remains above 5°C through the winter is ideal; the plants thrive in cooler conditions than most tropical house plants and perform best in a temperature range of about 5 to 15°C during the winter growing season. Temperatures that are too warm (above 15 to 20°C) during the growing season can reduce the quality and number of flowers; veltheimia flowers best when the winter growing period is cool and bright. Some UK gardeners in very mild coastal areas have successfully kept veltheimia in sheltered, south-facing positions outdoors under a south-facing wall with generous mulch protection from November to March, but this is very much an exceptional situation; in the vast majority of UK gardens, greenhouse or conservatory growing is required.

Q: How do I grow veltheimia in the UK?

Veltheimia is grown in the UK as a bulb in a container in a cool greenhouse, conservatory, or frost-free porch; plant the bulb in late summer (August to September) in a pot about 15 to 20 cm in diameter with freely draining, loam-based compost (John Innes No. 2 or 3 with 20 to 25% additional grit); the upper third of the bulb should be above the compost surface. Position in the brightest available light in the greenhouse or conservatory from September to May; bright light is essential for compact leaf growth and a good flower spike. Begin watering gradually from September as the leaves start to emerge; water moderately throughout the winter growing season (from autumn to spring) allowing the compost to partially dry between waterings. In December to March, the flower spike emerges; this is the showpiece of the plant. As the leaves begin to yellow and die back naturally from April to May, gradually reduce watering to none by June; keep the compost completely dry from June to August. The bulbs can remain in the same pot year after year; repot every three to four years in late summer when fresh compost is needed. Feed monthly with a balanced or high-potash liquid fertiliser from October to March; do not feed during dormancy (June to August).

Q: Why is my veltheimia not flowering in the UK?

Veltheimia fails to flower in the UK most commonly because of one or more of the following: insufficient light during the winter growing season (veltheimia needs maximum available winter light to build the energy reserves needed to produce a flower spike; a poorly lit indoor position or a greenhouse with dirty glass significantly reduces flower production), insufficient summer dormancy (the bulbs need a completely dry rest period from June to August to reset the growth cycle; watering through summer prevents the dormancy that triggers autumn re-growth and flowering), temperatures that are too warm during the winter growing season (veltheimia flowers best in cool conditions of 5 to 15°C; a warm, centrally-heated conservatory or living room may be too warm, promoting leaf growth at the expense of flowering), or bulbs that are too young or too small (veltheimia bulbs need to reach a minimum size before they are able to flower; bulbs grown from offsets or seeds may take two to four years to reach flowering size). For the best flowering: maintain maximum winter light, ensure a completely dry summer rest, grow in cool conditions of 5 to 15°C through winter, and feed monthly from October to March with a balanced or high-potash fertiliser. A bulb that has flowered well in previous years but fails to flower in the current year should be checked for the above conditions and for congestion in the pot (repot and remove offsets if the pot is crowded).

Veltheimia bracteata (forest lily) is a South African winter-growing bulb producing broad, glossy, wavy-edged leaves from autumn and a striking spike of hanging, tubular, pink-purple flowers in December to March; one of the very few plants that flowers in midwinter. Grown as a cool greenhouse or conservatory pot plant in the UK, it needs a completely dry summer dormancy and a cool, bright winter growing period. Overwatering during dormancy is the most common cause of problems.

Overwatering or summer watering

Overwatering is the most common cause of veltheimia failure in UK cultivation; the bulbs are from a South African winter-rainfall, summer-drought climate and are fully dormant in summer. Any watering from June to August causes bulb rot; the symptoms appear when the plant re-emerges in autumn with reduced, curled, yellowing leaves or fails to emerge at all. Even during the active winter growing season, the compost should be allowed to partially dry between waterings; a constantly wet compost causes root rot even when the plant is actively growing.

What to do

Keep completely dry from June to August; store the pot on its side in a cool, dry, shaded position if possible to reduce the risk of accidental watering. Begin watering gradually in September as new leaves emerge; water moderately through the winter growing season, allowing the compost to partially dry between waterings. Use a very freely draining compost (John Innes No. 2 or 3 plus 20 to 25% grit) and ensure the pot has good drainage holes.

Cold damage

Veltheimia is frost-tender; exposure to temperatures below about 2 to 5°C causes the broad, glossy leaves to curl, go limp, and develop soft, water-soaked patches that later turn brown and collapse. Cold damage is most likely in an unheated greenhouse during a hard UK winter or in a conservatory that is not adequately insulated against severe frost. The actively growing winter leaves are the most vulnerable; a night when temperatures in the greenhouse fall to -2°C can cause significant leaf damage even if the bulbs survive.

What to do

Maintain a minimum temperature of 5°C in the growing space from October to May; a frost-free but unheated greenhouse is usually sufficient in most UK winters but may need a small heater on the coldest nights. A double layer of bubble polythene lining inside the greenhouse significantly improves insulation with minimal cost. Move veltheimia pots to the warmest part of the greenhouse (typically near the glass at shoulder height, not on the cold floor) to maximise warmth from any available winter sun.

Insufficient light

Insufficient light during the winter growing season (October to April) causes veltheimia leaves to become elongated, floppy, pale, and prone to curling; the plant grows toward available light sources and the leaves develop without the compact, upright, healthy form seen in well-lit conditions. Light-starved veltheimia also produces fewer or no flowers; the plant channels energy into leaf growth at the expense of the flower spike when light is inadequate.

What to do

Position veltheimia in the brightest available light from September to May; clean greenhouse glass maximises winter light transmission. In a conservatory or house, use the brightest south or west-facing window. Wipe any residue from leaves (not with a wet cloth, which can cause spotting) to maximise light absorption. Rotate the pot a quarter turn each week to encourage even leaf development rather than one-sided growth toward the light source.

Frequently asked questions

Why are my veltheimia leaves curling?

Veltheimia leaves curl most commonly because of overwatering or watering during summer dormancy (bulb rot; the plant needs to be completely dry from June to August; any summer watering causes rot), cold damage below 5°C (leaves curl and develop soft, water-soaked patches; maintain frost-free conditions; a minimum of 5°C from October to May), or insufficient light (elongated, floppy, curling leaves; position in the brightest available winter light; clean greenhouse glass). A dry summer rest and bright, cool winter growing conditions are the key requirements.

Is veltheimia hardy in the UK?

Veltheimia is frost-tender and is not hardy outdoors in the UK except in very exceptional, very mild coastal gardens. It is grown as a cool greenhouse, conservatory, or house plant. The minimum temperature is about 2 to 5°C; it performs best in a cool range of 5 to 15°C during the winter growing season. Temperatures above 15 to 20°C during growth can reduce flowering quality. A frost-free but unheated greenhouse is usually adequate in most UK winters.

How do I grow veltheimia in the UK?

Plant the bulb in late summer (August to September) with the upper third above the compost surface in a 15 to 20 cm pot of John Innes No. 2 plus 25% grit. Position in maximum winter light (September to May); water moderately, allowing partial drying between waterings. Feed monthly from October to March. Keep completely dry from June to August. The flower spike appears December to March; repot every three to four years in late summer. Minimum temperature 5°C.

Why is my veltheimia not flowering in the UK?

Veltheimia fails to flower most commonly because of insufficient winter light (position in maximum available light; clean greenhouse glass), a warm growing environment (flowers best at 5 to 15°C; avoid a warm heated room), incomplete summer dormancy (keep completely dry June to August; watering through summer prevents the dormancy that triggers flower production), or pot congestion (repot and remove offsets every three to four years). Feed monthly with high-potash fertiliser from October to March to build flowering energy.