Starting pansies (Viola × wittrockiana) from seed is a more economical way to grow a wide variety of cultivars than purchasing individual plants. Pansies are easy to start indoors in either the spring or fall. These short-lived, evergreen perennials will bloom in cool weather as long as the temperature stays above freezing.
When to Plant
Pansies are cold-hardy in U.S. Department of Agriculture plant hardiness zones 6 through 10 but they rarely survive the summers in USDA zones 8 through 11. Mature pansies grow in sun or part shade, but choosing a partially shaded location will extend their bloom time in warm weather. In most zones, pansies grow as cool-weather annuals.
Start pansy seeds indoors six to eight weeks before you plan to transplant them outside. In zones 8 and warmer, time seeding so you can plant pansies in the fall once the weather cools. The plants will flower during the fall, winter and spring before the summer heat kills them. In zones 5 and cooler, start seeds so you can set plants out two to four weeks before the last frost date in the area. In these areas, plants will flower through the spring, summer and fall until winter kills them. For zones 6 and 7, you can plant in the spring or fall.
Seed Starting Basics
Seed flats divided into cells or small individual pots work best for starting seeds. This gives each plant room to grow without getting the roots tangled with neighboring seedlings. Make sure all containers have drainage holes.
Fill each cell or pot with a soil-less seed-starting mix. These are usually a mixture of vermiculite and peat. Once the pots are filled, water them to thoroughly moisten the seed starting mix. Add more potting mix if it settles after watering, and water enough to make sure there are no dry pockets in the mixture.
Place one pansy seed in each pot and cover with a 1/8 inch layer of potting mix or clean sand. Cover the pots with plastic or damp burlap to keep in moisture. Remove this cover as soon as the seeds start to sprout. At temperatures between 65 and 75 degrees Fahrenheit, pansy seeds will germinate in 10 to 14 days.
Pansy seedlings are sensitive to sunlight, so keep new plants in the shade until they develop their second set of leaves. After that, they can stand direct sunlight as long as the soil is kept moist. Use a spray bottle to gently mist the soil while seeds are germinating and for the first few weeks of growth. Keep the soil moist, but not soggy.
When the seedlings have several sets of true leaves, begin fertilizing with a water-soluble fertilizer at 1/4 strength. For an all-purpose plant food with an N-P-K ratio of 24-8-16, mix 3/4 teaspoon of fertilizer with 1 gallon of water. Apply this fertilizer solution to the soil once a week in place of a regular watering. The rest of the week, water with plain water in the mornings often enough to keep the soil moist but not waterlogged.
When you are ready to move the pansies into the garden or pot them into a larger container, space plants 6 to 12 inches apart. The seed packet will have spacing recommendations for individual cultivars. Plant pansies in nutrient-rich, well-drained soil at the same depth they were previously growing. Water the seedling thoroughly. Mature pansies require 1 inch of water per week.