France Doucet
Answer: I know this is going to sound weird, but… would it be possible to move your plant to a windier spot? When this plant is constantly moved by gusts of wind since it starts to sprout in the spring, it produces stronger stems. When it is protected from the wind, like with a hedge, a wall or a fence, it produces taller but weaker stems. When a gust of wind suddenly comes barreling through, the weak stems can’t handle it and down they go! Expose it to more wind from the start and your giant fleeceflower will keep on standing tall.
And your soil moist is not a factor as this perennial tolerates both moist soil and dry soils.