The Germination of Bellflower Seeds

Seed Collection and Preparation

• Campanula species produce seeds within dehiscent capsules, meaning that the capsules open when the seeds are mature and must be harvested from the plant before the seeds are shed. Dry the capsules on a screen with a sheet underneath to catch the seeds. Campanula seeds must be stratified for three weeks in a cold refrigerator or a similarly chilly environmental that will imitate cold winter weather.

Germination Medium and Requirements

• Sow the small Campanula seeds on top of a suitable germinating medium indoors. Do not cover them with soil and provide the seeds with adequate light, a requirement for germination. Keep the temperatures around 75 degrees Fahrenheit. Provide the seeds with even, constant moisture until they germinate. If the formation of mold atop the germinating medium is a potential problem, use bottom watering. Campanula seeds can also be sown directly outdoors once the soil warms up in the spring. Cover the seeds with no more than one-eighth inch of soil and space them 12 to 18 inches apart. Campanula seeds take 14 to 21 days to germinate.

Cold Germination Exceptions

• Certain species of Campanula germinate best at a cool temperature, so maintain a germination environment at about 41 degrees Fahrenheit for best results. These species include spreading bellflower, or C. patula, C. saxifraga, C. aucherri, C. cochlearifolia, C. punctata, C. rubriflor and others.

Additional Temperature Exceptions

• Some types of bellflower seeds require multiple temperature changes to germinate. Keep the seeds of these species at 68 degrees Fahrenheit for a month, move them to an environment kept at 32 degrees Fahrenheit for six weeks, and then keep them at 50 degrees Fahrenheit until germination. Species that require this temperature-adjusting regimen include C. allionii, C. latifolia "Alba", C. cenisia, C. barbata, C. raineri and C. waldsteiniana.