Why Are My Galanthus Leaves Curling?

Narcissus eelworm

Narcissus stem and bulb eelworm (Ditylenchus dipsaci) is the most serious pest of galanthus in UK gardens. The microscopic nematode lives inside the bulb and leaf tissue, causing characteristic distortion of the emerging leaves. Infested snowdrop leaves are twisted, curled, and often show yellow blotching or uneven colouration. The leaves may be stunted and the plant may produce no flower, or the flower stalk may be distorted. When you cut through an infested bulb, you can see characteristic brown ring markings in the white flesh. Eelworm spreads through infected bulbs, through contaminated soil, and on tools. There is no chemical treatment available to gardeners and the damage is irreversible.

What to do

• Dig up and destroy all plants showing characteristic twisted, curled, blotched leaves. Do not compost eelworm-infected material or move soil from infected areas.
• Do not replant galanthus in an infected area for at least six years. The eelworm can survive without a host in moist soil for several years.
• Purchase only certified, eelworm-free stock from reputable galanthus specialists. Eelworm spreads readily on imported bulbs.
• Disinfect tools between working in different areas. A diluted garden disinfectant solution is effective.
• Do not divide and replant from infected clumps, as this spreads the eelworm to new areas.

Waterlogging

Waterlogging is a common cause of galanthus decline. Snowdrops prefer moist, humus-rich, well-drained soil that does not dry out in summer. While they tolerate and even prefer consistently moist conditions, persistently waterlogged, anaerobic soil causes the bulbs to rot. The narrow leaves emerge yellow, curl, and the plant collapses. This is most common in heavy clay soil during a wet winter or in low-lying positions that collect water. It is particularly damaging when waterlogging occurs during the summer dormant period when the bulbs have no active growth to resist infection.

What to do

• Plant galanthus in moist but free-draining soil. The ideal position is in dappled shade under deciduous trees, where the soil is humus-rich, retains moisture through spring, and dries somewhat in summer under the tree canopy.
• Improve drainage in heavy clay by incorporating generous amounts of leaf mould or garden compost combined with coarse grit.
• Avoid low-lying, waterlogged positions. If the garden is predominantly heavy clay, raise beds slightly to improve drainage, or grow galanthus in containers in a free-draining but moisture-retentive compost.

Grey mould (Botrytis)

Grey mould (Botrytis galanthina) is a specific snowdrop disease that can cause significant losses in dense plantings during mild, wet winters. The fungus attacks the leaves, flowers, and stems, covering affected tissue in a characteristic grey, fuzzy mould. Infected leaves curl, darken, and collapse. The disease spreads rapidly between plants in dense, damp conditions with poor air circulation. Botrytis galanthina also produces sclerotia (small, hard resting bodies) that persist in the soil and infect bulbs in subsequent years.

What to do

• Remove and bin affected plant material immediately at the first signs of grey mould. Do not compost botrytis-infected material.
• Improve air circulation around dense plantings by thinning and dividing overcrowded clumps.
• Avoid planting snowdrops in very densely humid positions with no air movement. Good air flow significantly reduces botrytis risk.
• A copper-based fungicide applied at the first signs of infection provides some protection, though established botrytis is difficult to eradicate completely.

Overcrowding

Overcrowding reduces the vigour and flowering performance of galanthus over time. As clumps build up over many years, the bulbs compete for water and nutrients and individual bulbs produce progressively smaller leaves that may curl outward as they lack the space to grow normally upright. The flowers become smaller and less numerous. This typically becomes a significant problem after ten or more years in undivided clumps. Dividing and replanting refreshes the colony and restores full flowering performance.

What to do

• Divide overcrowded galanthus clumps every three to five years, immediately after flowering while still in full leaf (in the green). This is the most important maintenance task for keeping snowdrops healthy.
• Separate gently into individual bulbs or very small groups and replant immediately at 8 to 10 cm apart. Do not allow the bulbs to dry out between lifting and replanting.
• Enrich the replanting area with leafmould to restore humus content depleted by years of bulb growth.

Dry bulb failure

Galanthus bulbs sold dry in autumn in bags, like many other spring bulbs, perform very poorly compared to plants lifted and replanted in the green. Dry snowdrop bulbs lose viability rapidly and many fail to establish or produce only weak, curling leaves in their first year. This is the most common reason newly purchased snowdrops disappoint. The bulbs are not adapted to summer desiccation in the way that tulip or narcissus bulbs are.

What to do

• Wherever possible, purchase galanthus as container-grown plants or as in the green divisions in late winter and early spring, when they establish with much greater success than dry-planted autumn bulbs.
• If you must plant dry bulbs in autumn, do so immediately on receipt and do not allow them to dry out further. Soak for two to three hours in lukewarm water before planting.
• Plant dry bulbs slightly more shallowly than recommended (4 to 5 cm rather than 8 to 10 cm) and in a position with consistent soil moisture to maximise establishment success.

Frequently asked questions

Why are my snowdrop leaves curling?

Snowdrop leaves curl most often from narcissus eelworm (Ditylenchus dipsaci) or waterlogging. Eelworm infestation causes the narrow, strap-like leaves to emerge twisted, curled, and distorted, often with characteristic yellow blotching. Waterlogging in heavy clay or poorly drained soil causes the leaves to yellow and curl as the bulb base deteriorates. Both problems are common in established UK snowdrop colonies.

Why are my snowdrops not flowering?

Snowdrops that produce leaves but no flowers are most often overcrowded and need dividing, have been planted dry (as dried bulbs in autumn, which perform very poorly), or are suffering from eelworm damage. Divide overcrowded clumps immediately after flowering, while still in leaf (in the green), replanting individual bulbs at 8 to 10 cm apart. Never plant dried snowdrop bulbs if you can avoid it: in the green divisions or pot-grown plants establish far more reliably.

When should I divide snowdrops?

Divide snowdrops immediately after flowering while they are still in leaf, a practice known as dividing in the green. This is typically from late February to April, depending on the variety and season. Dig up the clumps, separate gently into individual bulbs or small groups, and replant immediately at 8 to 10 cm apart and 5 to 8 cm deep. Do not allow the bulbs to dry out between lifting and replanting.

Do snowdrops spread on their own?

Yes, snowdrops spread in two ways: by producing daughter bulbs (offsets) which gradually enlarge the clump, and by self-seeding where the seeds are dispersed by ants attracted to the elaiosome (a fatty appendage on the seed). Both processes are slow, so the most effective way to establish a large colony quickly is to divide existing clumps in the green and replant more widely spaced. Well-established snowdrop colonies can be self-sustaining for many decades.