From our perspective as Digitalis plants, yes, we absolutely spread, and we have evolved a highly effective strategy to do so. We are primarily biennials. In our first year, we focus our energy on establishing a low rosette of leaves, building up strength in our roots. In our second spring, we send up our magnificent flower spire, which is not just for your admiration but is a powerful beacon for bees. After pollination, each flower can produce a seed capsule containing hundreds, even thousands, of microscopic seeds. This prolific seed production is our primary method of colonizing new territory and ensuring our genetic lineage continues.
Our seeds are engineered for travel. They are tiny, dry, and lightweight, perfect for being carried by the slightest breeze. A gentle wind can shake our ripe seed capsules and send our offspring sailing several feet, or even meters, away from the parent plant. This is how we naturally spread to find new, uncrowded patches of soil to germinate in. Furthermore, you, the gardener, are an unwitting accomplice in our spread. When you brush against our dry seed stalks, walk past us, or especially when you dig or cultivate the soil near our base, you help scatter our seeds far more effectively than the wind alone ever could.
If you wish to control our enthusiastic self-seeding, you must interrupt our reproductive cycle. The most effective method is to remove our flower spike before we complete our mission. As soon as the majority of flowers on our spire have faded and begun to drop, you should cut it down. This is known as deadheading. If you do this before the lowest seed pods form and ripen, you prevent us from producing any viable offspring. Simply snipping off the spent flower spike and disposing of it (do not compost it if you wish to prevent spread) halts the entire process. If you wait too long and the pods have formed, you must be very careful; place a bag over the seed head before cutting to capture all the seeds.
It is important to understand that the new plants that sprout from our scattered seeds, often called "volunteers," will not always be identical to their parent. If the original plant was a hybrid cultivar, its seedlings may revert to a different color, size, or habit. They will be the native species, often Digitalis purpurea, which is typically a lovely shade of pinkish-purple. Therefore, to ensure you get exact copies of a specific variety, you will need to purchase new plants or sow purchased seeds. Allowing us to self-seed provides a charming, naturalized look but comes with the trade-off of unpredictability.
