Catnip (Nepeta cataria) is a perennial herb in the mint family, known globally for attracting and affecting felines. This plant is also cultivated for herbal teas and as a garden pest deterrent. Harvesting the seeds allows gardeners to propagate new plants, ensuring a continuous supply. Saving these seeds requires understanding the plant’s life cycle and collecting the viable reproductive material for planting in the next growing season.
Identifying When Catnip Seeds Are Ready
The correct timing for harvest is tied to the plant’s visual transition from flowering to seed setting. Viable catnip seeds are found within the spent flower heads, which must be fully mature. Initially, catnip produces dense spikes of small, whorled flowers, often white or lavender in color.
As the season progresses, typically in late summer or early autumn, these flowers fade and dry out. The most reliable indicator of maturity is the color and texture of the calyxes, the cup-like structures that now encase the seeds.
These structures must transition from green to a dark gray or brown, becoming completely dry and brittle to the touch. Collecting the seed heads too early, while they are still pale or soft, will yield non-viable seeds.
Collecting the Seed Heads
Once the flower spikes have dried completely on the plant, the collection process can begin, ideally on a dry, sunny day when residual moisture is minimal. Using a pair of clean, sharp shears, snip the dried flower stems a few inches below the seed heads. Handle the stems gently to prevent the ripe seeds from scattering prematurely.
A practical method to contain the harvest immediately is to hold a large paper bag beneath the stem as you cut it. Placing the snipped material directly into the bag ensures that any seeds that loosen upon cutting are captured.
The paper bag also allows for air circulation, which is necessary to continue the drying process and prevent mold formation.
Processing and Cleaning the Seeds
After collection, the dried flower heads often require a final drying period of a few weeks in a warm, low-humidity location to ensure the seeds are completely desiccated. Catnip seeds are extremely small, and separating them from the remaining plant material, known as chaff, is the most labor-intensive step.
The initial separation involves gently crushing the brittle seed heads inside the paper bag or over a large, shallow container. This action breaks apart the dried calyxes, freeing the tiny, dark brown or black seeds.
The mixture of seeds and chaff can then be cleaned using winnowing, which relies on the difference in weight between the two components. By pouring the mixture slowly in front of a gentle air current, such as a light breeze or a fan on a low setting, the lighter chaff is blown away while the heavier seeds drop straight down. For a more refined separation, the material can be sifted through a fine mesh screen or sieve, allowing the small seeds to pass through while retaining the larger pieces of stem and debris.
Proper Storage for Viability
Successfully saving the seeds requires storing them under specific conditions that maintain their ability to sprout for future seasons. Viability is primarily threatened by high temperatures and high humidity, which can prematurely activate or rot the seed embryos.
The cleaned catnip seeds must be stored in a cool, dark, and dry environment. Airtight containers, such as small glass jars or sealed zipper bags, are effective for preventing moisture from reaching the seeds.
For maximum longevity, the sealed containers can be placed in a refrigerator or a cool, dark cellar where the temperature remains consistently low. Labeling the container with the date and the plant variety ensures accurate record-keeping.