Natural Height Control of Container Grown Eupatorium fistulosum

Eupatorium fistulosum, Joe-Pye Weed, is a tall [up to 3 m (10 ft)], upright, native perennial that produces large panicles of rosy purple flowers in the summer. However, its height limits its production in containers because tall plants easily blow over and can be difficult to ship. Rooted liners were transplanted into 3.8 liter (#1) containers on two different dates in the spring to shorten the period of vegetative growth before plants initiated flowers in late spring/early summer. Height increase was essentially halted when flowers were initiated, shortly before plants would be shipped. While plants were at least 64% taller than the maximum acceptable height of 61 cm (24 in), it was evident that manipulating the transplant date could be used to reduce the natural height of this species for container production. Moreover, it was shown that a low rate of controlled release fertilizer could be used in production, thereby reducing nutrient runoff. There was no strong evidence that fertilizer rate affected plant height or quality.