There are about twenty species of Digitalis and of those about four a good garden plants. One of these, common foxglove (D. purpurea), is the most popular and the one most people envision when foxgloves are mentioned. It is a tall biennial, four to five feet in height, and has two to three inch long flowers that are usually lavender with purple and white spots. Foxgloves are cross-pollinated by insects so only one variety should be planted at a time to maintain the purity of a strain if the seeds are going to be collected. Purple flowers are dominant to white and plants bearing them can be recognized before the flowers open by the purple streaks on the stems. Most hybrids will not breed true the exception being the short lived perennial, strawberry foxglove (D. x mertonensis), a cross between D. purpurea and D. grandiflora. It is 3-4 feet tall and has rose colored flowers. Foxgloves like cool temperatures, some shade especially in hot climates, and fertile moist soil.
When collecting seed choose plants that have an early bloom time and resistance to crown rot. Since all parts of the plant are toxic, the use of gloves is recommended.
Foxgloves produced capsules containing an abundance of small seeds. Since the flowers bloom from the bottom of the stalk upward, the first seed capsules will be seen below the flowers. After the petals wilt and die, the seed capsules ripen, turn brown, and split to release the seeds. They can be harvested individually as they dry and open or when the entire stalk bears dried capsules.
Directions for Collecting Seed
1. Snip the dried, splitting seed capsules off the plants catching them in a white container.
2. Crush the pods gently to release the seeds and shake the container to facilitate seed release from the capsules.
3. Separate the seeds from the chaff by using a fine gauge strainer (a tea strainer is a good choice) shaken over a white plate or into a white bowl.
4. Dry the seeds well for several days on paper towels.
5. Store in a labeled plastic bag placed in a small jar and put in a dry, dark, cool place like the refrigerator.