Flower · Asparagaceae
When to sow lily of the valley
Intensely scented white bells in late spring, and one of the very few plants that will colonise dry shade under trees. Spreads by underground runners, thoroughly, which is either the point or the problem.
Hardy in USDA zones
2a to 7b
Winter cold sets the limit here, not the calendar.
Frost tolerance
Very hardy
How much cold the plant itself will take.
Those weeks become real dates once you name a place.
Timing, in frost-relative terms
Nothing about a standing crop is sown to a calendar. Once planted, lily of the valley stay in the ground for years, so the question is not when to sow but whether your winter is survivable and your planting window is open. Both answers come from your frost dates.
- Hardy in USDA zones 2a–7b.
Getting the timing right
Plant the pips - single-budded root divisions - while dormant in autumn or very early spring, 3cm deep with the bud just below the surface. Site it where spreading is welcome; it is difficult to remove once established and will out-compete smaller shade plants.
Frost tolerance
Hardy to about -35C and needs a cold winter to flower, which is why it performs poorly in mild-winter climates. All parts are seriously poisonous, including the water in a vase of cut stems.
Classified as very-hardy, with damage expected below -35°C (-31°F)-31°F (-35°C).