Petunias are popular flowering annuals, known for their trumpet-shaped blooms and long flowering season. While many gardeners purchase established seedlings, growing petunias from seed offers access to a much wider array of colors and forms. Petunia seeds are small and require light to germinate, but they sprout reliably under warm, moist conditions. Finding the right source for quality seeds is the first step in successfully cultivating these vibrant plants.
Online Specialty Seed Companies
Purchasing petunia seeds through dedicated online specialty companies provides the greatest breadth of genetic diversity. These seed houses often carry hundreds of varieties, including heirloom types and the newest, patent-protected F1 hybrid varieties not yet available in physical stores. Gardeners seeking rare color combinations or specific growth habits, like miniature or unusual double-flowered types, will find these catalogs the most comprehensive resource. The detailed growing information provided online often includes specifics on ideal germination temperatures, light requirements, and necessary hardening-off procedures before transplanting outdoors.
Reputable specialty seed companies typically maintain higher standards for seed viability, which refers to the percentage of seeds expected to germinate. They store seeds in carefully controlled environments, ensuring the delicate embryos remain dormant and protected until planting. This rigorous quality control usually results in better success rates compared to seeds stored in less controlled retail settings.
When buying online, factor in shipping costs and delivery time. Specialized seed companies usually ship year-round, but order well in advance of the desired sowing date, as processing delays are common during peak spring periods. While large e-commerce marketplaces offer convenience, they may feature third-party sellers whose storage conditions and viability guarantees are harder to verify. Choosing a dedicated seed retailer often minimizes the risk of receiving older, less vigorous seed stock.
Local Nurseries and Retail Stores
Independent local nurseries and garden centers provide an immediate source for petunia seeds, often curated specifically for the regional climate. Staff can offer valuable, localized advice regarding the best varieties suited for microclimates or specific soil conditions, sometimes recommending types with earlier bloom times. While the selection might be narrower than an online catalog, the seeds sold are often from trusted national suppliers and are typically rotated to ensure freshness. The ability to ask targeted questions about cultural practices is a distinct advantage of shopping locally.
Large chain home improvement stores and discount retailers also stock petunia seeds, offering convenience and generally lower prices. Their inventory is usually limited to the most popular and commercially successful varieties, such as standard Grandiflora or Multiflora types. The primary benefit of these physical locations is the ability to purchase and plant seeds immediately without waiting for shipping.
Gardeners purchasing seeds in person can inspect the seed packets directly for packaging or “packed for” dates. Choosing the freshest possible seed stock is important because petunia seed viability naturally declines over time, even under good storage conditions. Checking the date helps ensure that the seeds have not been sitting on a shelf for multiple seasons, which can significantly reduce germination rates.
Key Considerations When Selecting Petunia Varieties
Flower Structure
Petunia seeds fall into distinct categories based on their resulting flower structure and growth habit, which should guide the selection process. Varieties are commonly grouped into single-bloom types, which have five fused petals, or double-bloom types, which feature ruffled, layered petals resembling small carnations. Double blooms tend to require slightly more care and may struggle in heavy rain, but they offer a denser, more luxurious appearance in containers.
Growth Habit
Plant architecture differentiates between upright and trailing forms. Grandiflora types are traditional upright growers, producing large flowers excellent for containers and garden beds. Spreading or trailing types, often marketed under names like Wave or Surfinia, aggressively sprawl up to four feet and are ideal for hanging baskets or groundcover applications. These spreading varieties are generally more tolerant of heat and adverse weather conditions than the larger-flowered Grandiflora types.
Seed Type
Note whether seeds are raw or pelleted, as this affects the ease of sowing. Petunia seeds are tiny, resembling fine dust, making them difficult to space properly. Pelleted seeds are encased in a clay coating, making them larger and easier to handle and sow individually, although this pellet must remain moist after sowing to dissolve and allow germination. Always confirm the seed viability date printed on the packet, as this estimate directly correlates with the expected germination success rate.