Plant Spreads Into Other Plantings - Invasive Variety
If a purple loosestrife plant vigorously spreads into other plantings in the yard, and young seedlings are found popping up everywhere, this indicates that the wild, invasive form of this plant is on the property. As early in the season as possible, cut off all flowering stems and put them in a bag for the trash. Try to prevent any seeds from falling on the ground. Then dig up all existing plants, and discard them. Replant with one of the recommended varieties above.
Purple loosestrife has no significant disease and insect problems.