"The creation of a thousand forests is in one acorn." - Ralph Waldo Emerson
Winter is winding down and spring is just around the corner! The absence of cold temperatures triggers the awakening of plants and stimulates the early stages of seed growth. A seed contains the genetic material (DNA) for future generations—whether it becomes a diminutive violet or a mighty oak! At Midwest Groundcovers, we propagate approximately 80% of our native species by seed. In order for seeds to wake from a state of dormancy and germinate, the temperature, moisture, air and light conditions must be acceptable. Our growers are well-versed in the optimal conditions needed, for each of the many native plant species that we propagate using this method, to ensure rapid and uniform germination.
Propagation begins each year in late summer/early fall, when we hand collect ripening seed from our mature plant stock at the Midwest Natural Garden and St. Charles nursery. Our native stock plants represent local ecotypes that are genetically adapted to our local growing conditions. A crew of 2-3 growers harvest and clean the seed using various sizes of screens to separate out the chaff and dust. The seed is collected in large plastic bags, labeled with the date and genus/species and then stored in the cooler until needed. Then starting in November, our growers begin a process called stratification that involves mixing the seed with fine silica sand and water following a species-specific ratio based on seed size. For example, a very fine seed like Lobelia is mixed using a ratio of a pinch of seed to 4 cups of moist sand, while a large seed like Silphium is mixed using a ratio of ½ cup of seed to 4 cups of moist sand. Once mixed, these bags are returned to the cooler for 10-120 or more days to allow for the water to break down the seed coating and activate growth. Some seeds with an extremely hard coat, such as Baptisia australis, benefit from scarification, which may involve using sandpaper to help break down the outer coating to allow water inside. Other seeds, such as Callirhoe involucrata benefit from a hot water treatment to open the seed coat. Woodland ephemerals, such as Asarum, may require two dormancy periods. Dormancy helps to ensure the survival of a plant species by allowing some ungerminated seeds to survive a natural catastrophe.
Germination may take several days to several weeks depending on the species and time of year sown. Some crops, such as Sporobolus heterolepis, do not require stratification and can be sown immediately into trays. Antonio Betocourt, one of our growers in St. Charles, sows Sporobolus seed using a 50/50 mix of peat moss and perlite (produced by our sister company, Midwest Trading). The seeds are then lightly covered with a fine layer of vermiculite to promote water retention. Once planted, the trays are hand misted every 1-2 days to encourage germination. Growing conditions are carefully monitored and maintained using heaters, fans and high-pressure sodium grow lights. Before long the seedlings are transplanted into plugs and eventually into larger #1 and #3 containers. Thanks to Mother Nature and the skill of our knowledgeable and attentive growers, a 1-gallon plastic bag of S. heterolepis seed (approx. 3.5 kg) may produce over 80,000 #1 size plants in one season!