How to Start Strawberry Seeds Indoors
Strawberry plants are perennials that can produce fruit year after year, beginning the second year after starting them from seeds. You can start strawberry seeds indoors six to eight weeks before the last frost in your area. Some strawberry seeds need to be cold treated prior to germination, so make sure to check the specific requirements of the type of strawberries you plan to grow before you plant them indoors. Most strawberry plants germinate within 21 days and will be ready to transplant into the garden or into containers within two months.
Cold treat strawberry seeds by wrapping them in plastic wrap and placing them in the freezer for 30 days. Remove them from the freezer and place them in the refrigerator for several days. Remove them from the fridge and place them in a slightly warmer location such as an unheated garage or basement.
Gradually increase the temperature around the seeds over the next several days until they reach room temperature. Not all species need to be cold treated. Skip this step for those cultivars or if the nursery has already cold-treated the strawberry seeds.
Fill the seed trays 3/4 full with a sterile, soil-less planting medium such as vermiculite or another commercial seed starting mix. Look for seed trays and soil-less planting medium at your local garden supply or discount store.
Spread two to three strawberry seeds on top of the planting medium in each tray section. Cover the seeds lightly with a layer of soil-less medium. Water the seeds and cover them with a sheet of plastic wrap.
Place the tray in direct sunlight or beneath fluorescent grow lights. Flip the plastic wrap every day to avoid condensation build-up. Keep the seeds moist.
Watch for the second set of true leaves on the strawberry seedlings. Thin out the weakest plants and move the seedlings into larger containers. Wait until all threat of frost has passed to plant your strawberry plants in your garden. Plant them anytime in containers that have good drainage and filled with slightly alkaline soil.