The small, yellow-green specks on the outer surface of the strawberry are botanical fruits known as achenes. Each achene contains a single seed, making it possible to grow a new plant directly from the fruit you purchase. While this method is slower than using runners or crowns, it offers a rewarding path for gardeners. This process requires careful extraction, a necessary period of chilling to break dormancy, and precise management of the delicate seedlings.
Understanding Strawberry Genetics
Most commercial strawberries are complex hybrids (Fragaria × ananassa) resulting from deliberate cross-breeding. The common garden strawberry is octoploid, meaning its cells contain eight sets of chromosomes, which leads to high genetic diversity. When planting a seed from such a fruit, the resulting offspring will exhibit a mix of traits and will likely not produce fruit identical to the parent.
This genetic variability means growing from seed is a form of experimentation; the fruit produced may be smaller, less sweet, or have a different growth habit. In contrast, propagation using runners produces genetically identical clones. Growing from seed is best suited for genetically stable heirloom varieties or for those who enjoy the unpredictable nature of hybrid genetics.
Step-by-Step Seed Extraction and Preparation
Begin by selecting a fully ripe, healthy strawberry, preferably from an organic source to maximize seed viability. The simplest method is to manually scrape the achenes from the fruit’s surface. Gently shave off the outermost layer of the fruit, taking the achenes along with a tiny amount of pulp.
The achenes must be thoroughly cleaned to remove all traces of fruit pulp, which contains germination inhibitors. Place the extracted material in a small bowl of water and stir gently; viable achenes will sink, while pulp and non-viable seeds will float. Repeat rinsing until the water is clear, then spread the clean achenes on a paper towel to air dry completely for one or two days.
Strawberry seeds require cold stratification to break dormancy, mimicking winter conditions. Place the dry achenes into a sealed container with a slightly moistened medium, such as peat moss, sand, or a damp paper towel. Refrigerate the container at 34 to 41 degrees Fahrenheit (1 to 5 degrees Celsius) for a minimum of three to four weeks. This chilling period signals that the cold season has passed, triggering germination.
Planting and Early Seedling Management
After stratification, the seeds are ready to be sown in a sterile seed-starting mix, which reduces the risk of fungal disease. Use a shallow tray or small pots filled with the dampened mix. Strawberry seeds need light to germinate, so they should be surface-sown by sprinkling them across the soil and lightly pressing them down. Do not cover the achenes with a thick layer of soil; a planting depth of no more than 1/8 inch is sufficient. To maintain high humidity and consistent moisture, cover the tray with a clear plastic dome or plastic wrap. Place the container under bright grow lights or on a sunny windowsill, maintaining a consistent temperature between 65 and 75 degrees Fahrenheit.
Germination is slow, taking anywhere from one to six weeks before the first sprouts emerge. Once the seedlings develop their first true leaves, remove the plastic covering to improve air circulation and prevent damping-off disease. As the young plants grow, thin them out by clipping the weaker ones at the soil line, ensuring the remaining seedlings have adequate space.
When the seedlings have grown for about six weeks and are robust enough to handle, they can be transplanted into individual, slightly larger pots. Before moving the young plants permanently outdoors, they must undergo “hardening off” to acclimate them to the harsher outdoor environment, including direct sunlight and wind. Over a period of one to two weeks, gradually expose the plants to outdoor conditions, starting with an hour in a sheltered, shady spot and slowly increasing the time and intensity of light exposure each day.