Successful cultivation starts with high-quality, viable seeds. A “good” seed has the internal resources and genetic integrity needed to germinate quickly and develop into a healthy plant. Assessing viability before planting saves cultivators time, effort, and resources that would otherwise be wasted on non-starters. Evaluation moves from simple observation to active testing to confirm the seed’s potential.
Visual and Physical Assessment
Determining a seed’s quality begins with a visual inspection that requires no special tools. Mature, viable seeds typically display a dark coloration, ranging from deep brown to black, often featuring distinctive mottling or “tiger stripes.” This dark pigmentation indicates the seed has fully matured and hardened on the parent plant.
Pale white or green seeds are usually immature and lack the energy reserves needed for growth. A healthy seed should have a hard, smooth outer coating. This protective shell should feel firm when gently pressed, resisting pressure.
A soft, brittle, or cracked shell suggests the seed is underdeveloped or physically damaged, exposing the embryo. Seeds that feel hollow or easily crush are non-viable, lacking the dense internal structure required for germination. While size varies by strain, plump, rounded seeds are generally more likely to possess necessary nutrients than shriveled or misshapen ones.
Practical Viability Testing Methods
After a visual inspection, active testing provides a stronger indication of a seed’s potential to sprout. The float test involves placing seeds in room-temperature water for one to two hours. Seeds that sink are typically considered viable, as their density suggests a healthy, well-developed embryo inside.
Seeds that float are often dismissed as non-viable, but this test is not definitive; some viable seeds float due to trapped air pockets. Therefore, floating seeds should not be discarded but should proceed to the definitive germination test. The most reliable method for confirming viability is a germination trial, such as the paper towel method.
The paper towel method involves placing seeds between two sheets of moist paper towel, sealed in a container to maintain humidity. This setup should be kept in a warm, dark environment, ideally between 70°F and 85°F (21°C to 29°C). The paper towel must remain consistently damp, like a wrung-out sponge, but never soaking wet, which causes rot by depriving the seed of oxygen. A successful test is confirmed by the emergence of a tiny white taproot, typically within 24 to 72 hours, though some seeds may take up to a week.
Understanding Why Seeds Fail
Even physically sound seeds can fail germination due to underlying issues related to history and storage. Pale or soft seeds often indicate maturity issues, having been harvested before fully developing the energy needed for sprouting. These underdeveloped seeds may lack a fully formed embryo or the necessary protective hard shell.
Age and storage environment are major factors that degrade viability over time, even for initially high-quality seeds. Seeds are living organisms, and their internal components break down faster when exposed to heat, light, or excessive humidity. Improper storage, such as temperature fluctuations or moisture exposure, can trigger a stalled germination process that kills the embryo without visible external signs.
Physical damage, while sometimes visible as cracks, can also be internal, resulting from rough handling during harvesting or transport. This internal trauma can destroy the embryo or the connection points needed for the root to emerge, even if the shell remains intact. While visual checks and the float test offer preliminary screening, failure to sprout under ideal conditions confirms the seed’s internal mechanism has been compromised, usually by poor storage or immaturity.