Salvia is a diverse and popular genus that includes both ornamental flowering plants and the culinary herb, sage. These plants are known for their vibrant, often spiky blooms that attract pollinators like hummingbirds and butterflies. Growing Salvia from seed is a cost-effective strategy, allowing gardeners to cultivate numerous plants for far less than purchasing individual nursery starts. This process provides control over the plant’s early development, leading to robust specimens ready for the garden.
Gathering Supplies and Timing the Sowing
Starting Salvia seeds indoors is the most reliable method for most varieties, especially when aiming for blooms in the first year. Sow seeds six to ten weeks before your area’s average last expected frost date, allowing time for seedlings to mature before transplanting. While some annual varieties can be direct-sown outdoors after the danger of frost has passed, indoor starting ensures earlier flowers and a higher germination rate.
Before sowing, gather all necessary materials. Use a lightweight, sterile seed-starting mix that drains well and prevents fungal issues. Containers should be seed trays, cell packs, or peat pots with adequate drainage holes. A clear plastic dome or plastic wrap is needed to create a humid environment, and a seedling heat mat is highly recommended to maintain consistent soil temperature. Note that some perennial types may benefit from cold stratification to break seed dormancy.
The Step-by-Step Sowing Process
Begin by preparing your starting containers, filling them with pre-moistened seed-starting mix. The mix should be damp but not saturated, and you should gently firm the soil surface. Many Salvia varieties require light to germinate, meaning they should not be buried deeply beneath the soil.
Gently scatter two or three seeds over the surface of each cell, then lightly press them into the soil. Avoid covering the seeds with more than a thin dusting layer of soil or vermiculite. Water the cells gently using a fine misting bottle or, preferably, by bottom-watering the tray to avoid displacing the small seeds.
Immediately place the clear plastic dome or plastic wrap over the containers to lock in humidity and maintain a stable microclimate. Use clear labels to mark each tray with the specific Salvia variety and the date sown. This practice is important for tracking germination times and managing different varieties.
Nurturing Seedlings Until Transplant
Germination and Light Requirements
The initial condition for germination is warmth, with an ideal soil temperature range between 70–75°F (21–24°C). This temperature is best achieved by placing the trays on a heat mat. Maintain consistent soil moisture, being careful not to let the mix dry out, as this can quickly kill the delicate emerging root embryo. Germination typically occurs within a range of five to twenty-one days, depending on the specific variety.
As soon as the first sprouts appear, remove the humidity dome and immediately place the seedlings under a strong light source. Providing intense light is necessary to prevent the young plants from becoming tall and spindly, a condition known as “legginess.” Position a dedicated grow light two to four inches above the tops of the seedlings, providing 14 to 16 hours of light daily. Insufficient light is the most common cause of weak starts.
Thinning and Potting Up
Once the seedlings develop their first set of true leaves, you should thin them by snipping off all but the strongest plant in each cell to give the survivor space to thrive. If the seedlings outgrow their initial cells before the last frost, move them into slightly larger pots, such as three or four-inch containers. This step allows for continued, healthy root development before they are moved outdoors.
Hardening Off
About one to two weeks before the planned outdoor planting date, begin the process of “hardening off” the young plants. This involves gradually exposing the seedlings to outdoor conditions. Start with a few hours in a sheltered, shady spot and slowly increase the time and intensity of light and wind exposure over a seven to fourteen-day period. This crucial step prepares them for the garden environment and minimizes transplant shock.