Hardiness: USDA Zone 3a: to -39.9 °C (-40 °F) USDA Zone 3b: to -37.2 °C (-35 °F) USDA Zone 4a: to -34.4 °C (-30 °F) USDA Zone 4b: to -31.6 °C (-25 °F) USDA Zone 5a: to -28.8 °C (-20 °F) USDA Zone 5b: to -26.1 °C (-15 °F) USDA Zone 6a: to -23.3 °C (-10 °F) USDA Zone 6b: to -20.5 °C (-5 °F) USDA Zone 7a: to -17.7 °C (0 °F) USDA Zone 7b: to -14.9 °C (5 °F) USDA Zone 8a: to -12.2 °C (10 °F) USDA Zone 8b: to -9.4 °C (15 °F) USDA Zone 9a: to -6.6 °C (20 °F) USDA Zone 9b: to -3.8 °C (25 °F)
On Aug 8, 2011, auriculalady from Hoquiam, WA wrote:
I grew a Lythrum hybrid in Minnesota. It was not the least bit misbehaved. When I dug it up, it did not regrow from bits of root left in the soil. To this day I consider it an irreplaceable perennial in the garden. The invasion by Lythrum on the Minnesota river did not happen overnight. If you ignore a problem plant for fifty years, it is going to run amok. Some gardener planted it directly on the riverbanks. I don't know of any lakes overrun with it in Minnesota, so apparently birds don't carry the seed significantly.
On Oct 23, 2007, susybell from Vancouver, WA (Zone 8a) wrote:
WAC 16-752-400 - 415
purple loosestrife Lythrum salicaria
wand loosestrife Lythrum virgatum
It is prohibited to transport, buy, sell, offer for sale or to distribute plants, plant parts or seeds of Lythrum salicaria or L. virgatum into or within the state of Washington. It is also prohibited to transplant wildplants and/or plant parts of these species in the state of Washington.
The Lythrum quarantine applies to all Lythrum species including any hybrid cross and all named cultivars, including but not limited to plants with the horticultural names: morden pink, morden gleam, morden rose, the beacon, fire candle, brightness, lady sackville, Mr. Robert, Robert’s happy, roseum superbum, purple spire, rose queen, the rocket, dropmore purple and tomentosum.
On Jun 16, 2003, RubyStar from Madison, WI (Zone 5a) wrote:
Lythrum salicaria, L. virgatum, and all of their hybrids are responsible for a devastating amount of damage to North American wetlands. As stated above, even self-fertile hybrids can contribute hugely to the problem, by pollinating wild-growing stands.