Verbena is a hassle to start from seed as it needs cold stratification before planting and it has a fairly low germination rate. But a stand of verbena in bloom well makes up for the work that goes into preparing the seed for planting. Verbena comes in many forms: trailing, low-growing and back of the border tall. Flower colors are usually blue or purple, although red, pink and white cultivars are available. All verbena seeds need cold stratification to germinate. Stratification is to soften or penetrate the seed coat so the plant embryo can emerge. Not all seeds need stratification.
Use cold stratification to prepare verbena seed for planting. Start this process two weeks before your last predicted frost date.
Dampen two paper towels.
Sprinkle verbena seeds on one paper towel. It doesn't matter if the seeds touch, but they should form a single layer.
Place the second paper towel on top of the paper towel sprinkled with verbena seeds.
Place the paper towels in a plastic storage baggie. It's okay to fold the paper towels to make them fit inside the plastic storage baggie. The seeds need some air circulation so don't seal the baggie closed.
Place the baggie containing the paper towels in a freezer for 2 weeks. The temperature of the freezer doesn't matter as long as it is below freezing (32 degrees Fahrenheit).
Prepare the planting bed two to three days before the verbena seeds are ready to plant.
Work 3 to 4 inches of compost or well-rotted manure into the top 6 inches of soil. Rake the bed smooth.
Remove the verbena seeds from the freezer after two weeks of cold stratification.
Plant the seeds immediately by sprinkling over the prepared planting bed. Firm into the soil by gently pressing the back of a rake's tine over the seeds.
Water the seeds regularly until they germinate in 14 days. Allow the top ¼ to ½ inch of soil to dry between watering.