Geraniums, in their various forms, do produce seeds, though this fact is often obscured by the common practice of propagating them through cuttings. The confusion stems from the fact that two different groups of plants are commonly called “geraniums,” and both generate seeds, but their seed pods and propagation methods are distinct. Understanding how these seeds develop and are dispersed is the first step toward successfully collecting and growing them at home. The process requires careful timing due to the unique way many of these plants spread their seeds once they reach maturity.
The Distinction Between True Geraniums and Garden Geraniums
The name “geranium” refers to plants in two different genera within the family Geraniaceae. True geraniums belong to the genus Geranium and are commonly known as cranesbills, referencing the shape of their seed pod. These are hardy, herbaceous perennials that thrive in temperate climates, often used as groundcover or border plants.
The plants most people buy in garden centers, with showy, clustered flowers, are in the genus Pelargonium and are often called garden or zonal geraniums. Pelargoniums are native to South Africa and are tender perennials, grown as annuals in most regions because they cannot tolerate frost. While both types produce seeds, Pelargoniums are overwhelmingly propagated from vegetative cuttings to ensure the new plant is an exact clone, especially for hybrid varieties. True geraniums are often grown from seed, though many sterile hybrids must be divided or grown from cuttings.
How the Crane’s Bill Seed Pod Develops
The characteristic seed pod structure, known as the cranesbill, is a defining feature of the genus Geranium. After the flower is successfully pollinated and the petals drop, the base of the style begins to lengthen and thicken, forming a beak-like structure known as the rostrum. This rostrum contains five distinct fruit segments, called mericarps, each holding a single seed.
As the seed pod matures, it changes color, transitioning from green to dark brown, gray, or tan. As the rostrum dries, five strips attached to the mericarps curl back and spring away from a central column. This action explosively flings the ripe seeds away from the parent plant, often catapulting them a considerable distance. This ejection mechanism is why finding a mature seed pod that still contains its seeds is challenging for the home gardener.
Collecting and Germinating Geranium Seeds
The success of collecting geranium seeds depends on identifying the narrow window between ripeness and explosive dispersal. To collect seeds from true geraniums, you must monitor the crane’s bill pod daily as it darkens. The perfect time to harvest is just as the mericarps begin to slightly lift away from the central column, signaling imminent release. To prevent losing the seeds when the pod springs open, one effective method is to loosely cover the developing pods with small mesh bags or fine netting.
Once collected, many perennial cranesbill seeds require cold stratification to break dormancy, mimicking the natural winter cycle. This is achieved by placing the dried seeds in a labeled envelope in the refrigerator for up to 60 days before sowing. For both true geraniums and Pelargoniums, the hard outer seed coat may also benefit from scarification, which involves lightly scratching or nicking the coat to allow water penetration.
Seeds should be sown in a sterile, well-draining seed-starting mix and pressed lightly into the surface, as many geranium seeds need light to germinate. An ideal temperature range for germination is between 70 to 75 degrees Fahrenheit (21 to 24 degrees Celsius). While germination can be slow, taking several weeks for some varieties, consistency in moisture and temperature is important for success. Young seedlings should be transplanted into individual containers once they have developed their first set of true leaves, then gradually acclimated to outdoor conditions before planting.