Coreopsis, commonly known as Tickseed, is a versatile plant favored for its cheerful, daisy-like flowers and vibrant color. Including both annual and perennial varieties, it is generally easy to grow from seed. The optimal timing for sowing is not a single date but a choice between starting seeds early indoors or planting them directly into the garden soil.
Starting Coreopsis Seeds Indoors
Starting seeds indoors approximately six to eight weeks before the average last spring frost date provides the earliest blooms. This method gives young plants a head start, allowing them to develop a strong root system before being exposed to outdoor conditions.
Use a sterile, well-draining seed-starting mix in trays. Lightly press the small seeds onto the surface, as Coreopsis requires light to germinate and should not be covered with soil. Maintaining a consistent soil temperature between 65°F and 70°F is beneficial; germination typically occurs within two to three weeks. Once seedlings develop their first true leaves, they must be gradually acclimated to the outdoor environment through hardening off. This transition involves slowly increasing their exposure to sun and wind over seven to ten days, preparing them for transplanting after the danger of frost has passed.
Direct Sowing for Same-Season Blooms
Direct sowing is a viable option for many Coreopsis varieties, especially annual types, to produce flowers in the current season. This method should be performed once the threat of frost has ended and the soil has begun to warm up.
Optimal germination occurs when the soil temperature stays within the 55°F to 70°F range. Select a site that receives full sun and has well-drained soil, then loosen the top few inches of the planting area. Scatter the seeds lightly across the prepared surface and press them gently into the soil, ensuring they remain exposed to light. Maintaining continuous moisture is necessary until the seeds sprout, allowing the young plants to establish themselves quickly.
Direct Sowing for Perennial Establishment
A different timing is recommended for establishing perennial Coreopsis varieties. Sow these seeds in late summer or early fall, ideally eight to ten weeks before the first anticipated hard frost. This timing sets the stage for robust growth the following spring.
This fall timing utilizes cold stratification, where winter temperatures break the seeds’ dormancy. The seeds overwinter in the soil and germinate naturally once the ground warms in spring, resulting in stronger, more established perennial plants. After scattering and pressing the seeds onto the soil surface, apply a light layer of organic mulch for winter protection, especially in colder climates. This protects the seeds until their natural spring emergence.
Essential Care After Germination
Once Coreopsis seeds have germinated, specific care steps are required to ensure the seedlings mature into healthy plants. The first action is thinning, which involves removing weaker seedlings to provide adequate space for the strongest individuals. Seedlings should be spaced approximately 12 inches apart to allow for proper air circulation and root development.
Consistent moisture is important for young Coreopsis plants during their establishment phase. Keep the soil lightly moist, but never waterlogged, to encourage deep root growth. Although Coreopsis is generally not bothered by pests, monitor for issues like slugs, which can damage tender annual seedlings.