How to Grow Eupatorium from Seeds

Fill a seed flat, to within a half inch of the rim, with sterile, soilless seed starting mix. Seeds and seedlings have a tendency to rot when germinated in mixes that include soil.

Moisten the mix thoroughly, and scatter the eupatorium seeds across the surface. Sprinkle more of the soilless mix over the seeds to lightly cover them, and spray the top layer with water.

Place the seed flat in an area with indirect sunlight. Keep the mixture moist at all times during eupatorium's germination. Use water from a spray bottle to keep from disturbing the seeds. Eupatorium seeds germinate within 30 to 90 days, depending on species.

Transplant the seedlings into individual pots four to six weeks after germination. Fill the pots with a mixture of three parts of pine bark and one part each of peat moss and sand. Begin gradually moving them into full sun over the course of one week.

Plant the eupatorium seedlings into the garden after the last frost date. Amend the soil by digging in 3 inches of manure before planting. Dig the planting holes, fill them with water and when they drain, set the seedlings at the same depth as they've been growing in the individual pots. Plant them at least 2 feet apart.

Water the soil to a depth of 6 inches, and keep it slightly moist at all times. The most commonly cultivated eupatorium species wilt when they don't receive enough water so keep an eye on the plant during hot, dry weather.

Pinch 1 inch from the tips of the eupatorium stems to promote more flowering and to keep the plant compact. If you want the plant to remain small, cut each stem to half its length. Make the cut immediately above a set of leaves.

Dig up the eupatorium each fall. Drive a shovel through the rootball to divide the plant into pieces that each have one stem. Replant the divisions in a sunny area of the garden.

Allow the eupatorium's foliage to remain on the plant over the winter. Cut it back to 4 inches in height in early spring.