Growing strawberries from seed is a patient undertaking, often taking a full year before the first harvest. This method provides access to a wider selection of unique and heritage varieties than is possible with traditional crowns. Careful planning, starting with the correct planting density, is essential for ensuring a successful crop and establishing strong, singular plants.
Preparing Seeds and Starting Medium
Strawberry seeds possess dormancy, a natural mechanism preventing premature germination. To bypass this, seeds must undergo cold stratification, which mimics cold, moist winter conditions. Achieve this by sealing the seeds in a plastic bag with a lightly damp medium, such as peat moss or a paper towel. Place them in a refrigerator for four to six weeks at temperatures between 33 and 41°F.
This exposure breaks dormancy, signaling that it is safe for the seeds to sprout. Once stratification is complete, sow the seeds into a suitable starting mix. The ideal medium is a sterile, fine-textured, and well-draining seed-starting mix. This type of mix prevents disease and allows tiny roots to establish easily.
Precise Sowing: Depth and Quantity per Container
The primary purpose of sowing multiple seeds is to account for the naturally uneven and sometimes low germination rate. For small seed-starting cells, sow two to three seeds per cell. This density maximizes the chance of success, ensuring that each container yields at least one viable seedling without creating severe competition.
Strawberry seeds are “light-dependent germinators,” meaning they require light exposure to sprout. Do not bury them deeply. Instead, lightly press the seeds directly onto the surface of the pre-moistened seed-starting mix. They can be covered with a fine dusting of vermiculite or a light layer of soil, but the seeds must remain near the surface.
Maintaining the correct environmental conditions is necessary for germination, which can take anywhere from one to six weeks. The soil temperature should be consistently warm, ideally within the range of 65–75°F. Providing at least 12 hours of light daily helps encourage the seeds to break dormancy and begin growth.
Thinning for Stronger Growth
Since multiple seeds were planted to guarantee germination, the resulting cluster of seedlings must be reduced to a single, strong plant. Thinning removes the weaker seedlings to eliminate competition for light, water, and available nutrients within the small container space. Failure to thin results in multiple spindly, weak plants that will struggle to thrive when transplanted.
The optimal time to thin is once the seedlings have developed two to three sets of true leaves, which are the second set of leaves to emerge. Use small, sharp scissors or tweezers to snip the weaker seedlings at the soil line. Avoid pulling unwanted plants, which risks disturbing the delicate roots of the keeper plant. This action leaves the strongest seedling undisturbed, allowing it to utilize all resources and develop a vigorous crown.
Hardening Off and Transplanting
Before the young strawberry plants can be moved into their permanent garden location, they must undergo “hardening off.” This gradual process acclimates them to the harsher outdoor conditions. Sudden exposure to direct sun, wind, and temperature fluctuations can cause severe shock or death. This transition process should span seven to fourteen days.
Start by placing the seedlings outdoors in a sheltered, shaded location for just one to two hours on the first day. Gradually increase the duration each day, incrementally exposing them to more direct sunlight and wind. Ensure they are brought back inside if temperatures drop below 45°F. Once fully hardened off and the danger of frost has passed, they can be transplanted into the garden bed.
The final location should have well-drained soil with plenty of organic matter, and a slightly acidic pH between 5.5 and 6.8 is preferred. Proper spacing is determined by the variety. June-bearing plants are typically spaced 18 inches apart, while day-neutral varieties can be planted 10 to 12 inches apart. This spacing allows for adequate air circulation and root development, helping the plant establish and produce fruit the following season.