Phlox species, including garden phlox (Phlox paniculata) and creeping phlox (Phlox subulata), are mainstays in many landscapes, offering vibrant color throughout the growing season. Saving seeds allows gardeners to propagate their favorite varieties or share them with others. Successfully preserving these seeds requires careful timing and specific handling methods to ensure their viability for future germination. This guide covers collecting, processing, and storing phlox seeds to help secure the next generation of blooms.
Recognizing Phlox Seed Maturity
The correct timing for seed collection is crucial, as the window of opportunity is quite narrow. Phlox plants typically produce viable seeds in late summer or early fall, following the completion of their blooming cycle. After the petals drop, a small, round seed pod develops at the base of the former bloom.
Initially, this casing is pale green, but maturity is signaled by a color change to a dry, light brown or tan. The most significant challenge is the seed pod’s tendency for explosive dehiscence, meaning the pod can spontaneously burst open, scattering the seeds. This rapid expulsion is the plant’s natural method of seed dispersal, and it must be anticipated to prevent loss of the harvest. To maximize collection, harvest the pods when they are fully dry and brown but before they have cracked open.
Techniques for Harvesting Seeds
To prevent seeds from being scattered, a protective measure can be employed before the pods are fully mature. As the seed pods begin to swell and turn pale, a small mesh bag, such as a nylon stocking, can be gently tied around the entire spent flower head. This enclosure contains any seeds that are explosively ejected from the pod.
A more common method involves cutting the mature seed heads directly from the plant once they have dried to a brown color but remain intact. Use sharp, clean snips to cut the stem several inches below the seed head. The collected flower structure should then be placed into a clean paper bag. This container acts as both a drying vessel and catches any seeds that may burst out during the final stages of drying indoors.
Processing and Cleaning the Seeds
Once collected, the seed heads must be allowed to dry completely to ensure long-term viability. The open paper bag containing the plant material should be stored for several days in a cool, dark, and well-ventilated area. Adequate airflow is necessary to pull moisture from the pods and stems, preventing the growth of pathogens.
After a week or two, the material will be completely desiccated, and the seeds can be separated from the chaff (dried petals, stems, and pod casings). Pour the contents onto a flat surface and gently crush the dried seed pods to release the small, black seeds inside. Winnowing is an effective technique where the mixture is lightly tossed in front of a fan or breeze, allowing the lighter debris (chaff) to blow away while the heavier seeds fall straight down. Remove all residual plant matter, as remaining organic debris can retain moisture, leading to mold and rot during storage.
Proper Storage for Germination
The cleaned phlox seeds require specific conditions to maintain their germination potential until the next planting season. The ideal environment for seed storage is cool, dark, and dry, which slows down the seed’s metabolic processes. A sealed glass jar or a small paper envelope placed in a refrigerator provides a suitable environment, with temperatures consistently between 33°F and 40°F.
Before sealing, ensure the seeds are completely dry and label the container clearly with the phlox variety and the date of harvest. Perennial phlox seeds, such as those from Phlox paniculata, often benefit from cold stratification, which involves sustained exposure to cold temperatures to break dormancy. While annual phlox varieties generally do not require this, storing all phlox seeds in the refrigerator mimics the natural winter conditions that prepare seeds for spring germination.