How to Grow Ageratum From Seed

Commonly known as floss flower, plants of the genus Ageratum have long been grown in gardens for their dense, frilly flower clusters and attractive, lightly serrated leaves. The flowers appear in late spring and persist until autumn before fading and being replaced by clusters of brownish, oblong seed clusters. If gathered and stored in a cool, dry spot until spring, the seeds will germinate reliably and quickly grow into mature plants. For best results, sow seeds indoors six to eight weeks before the last frost.

3 1/2-inch starter pots
Potting soil
Medium-grit sand
Spray bottle
Propagation warming mat

Instructions

- 1
  Store ageratum seeds in a resealable plastic bag out of direct sunlight until early spring. Prevent mold by keeping seeds protected from temperature fluctuations and moist conditions.
- 2
  Sow the ageratum seeds in starter pots filled with a mixture of equal parts potting soil and sand. Place two seeds in each pot and press them into the surface. Spread a scant layer of sand over the seeds to hold them in place.
- 3
  Mist each starter pot with five or six spritzes from a spray bottle to moisten the soil a quarter-inch deep. Maintain moisture at that level for the duration of germination.
- 4
  Place the starter pots on a propagation warming mat near a large window with bright, direct sunlight. Set the propagation warming mat to 75 degrees Fahrenheit. Decrease the temperature to 58 at night.
- 5
  Watch for germination in five to 10 days. Thin seedlings to one per pot. Remove the weaker or less vigorous of the two ageratum seedlings from each pot.
- 6
  Continue watering the ageratum seedlings as described in step 3 until all danger of frost has passed. Plant them out in a partially shaded bed with moist, fertile soil once daytime temperatures rise above 70 degrees Fahrenheit.

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