21-28 days to emergence
Store verbena seeds in a plastic bag inside the refrigerator for one week prior to sowing. Do this approximately 10 to 12 weeks before the last hard frost in spring.
Sow the verbena seeds in individual 3-inch peat pots filled with potting soil. Place two seeds on the surface of the soil. Cover them with a 1/16-inch-thick layer of potting soil since the seeds require darkness to germinate.
Pour 5 to 6 tbsp. of water into each peat pot to moisten the top 1/2 inch of soil. Maintain moisture at that level until the plants mature, but let the surface of the soil dry out slightly between waterings to keep the soil from becoming waterlogged.
Place the potted verbena seeds in a warm and bright location where temperatures stay between 65 and 70 F at all times. Limit direct sun exposure on the pots to less than two hours each day.
Watch for germination in three to four weeks. Thin the seedlings as soon as they grow to 1 inch in height. Remove the less developed of the two verbena seedlings from each pot.
Keep the verbena seedlings near a large window or outdoors on a sunny, sheltered porch until all danger of frost has passed. Plant the young verbenas — peat pot and all — in a sunny bed with draining soil. Space the plants 12 inches apart.
Place verbena plants in locations providing full sun and well-draining soil. Allow enough space between each plant for the verbena to spread, which can vary from 12 to 24 inches or more. Dig planting holes the same depth of the containers holding the verbena plants. Place the plants in the hole, backfill the hole and soak with water to settle the soil around the plants.
Water the growing verbena plants with an inch of water weekly throughout the growing season, unless rainfall provides this. Apply a fertilizer, each month to the verbena flowers for the duration of the growing season.
Use pruning shears to cut away spent verbena blooms on the plants. Trim the top fourth of the stems to stimulate branching and additional blooms.