Get 15% OFF with code GROWNOW15
My Account Order Lookup Cannabis Guides Beginner Seeds Intermediate Seeds Master Seeds

How can I tell if a cannabis seed is viable?

  • Home
  • How can I tell if a cannabis seed is viable?
How can I tell if a cannabis seed is viable?

Determining whether a cannabis seed is viable—capable of germinating and producing a healthy plant—is an essential step for successful cultivation. Viable seeds lead to strong, productive cannabis plants, while non-viable seeds result in wasted time and effort. Below is a comprehensive guide to identifying cannabis seed viability using visual, tactile, and functional tests.

How can I tell if a cannabis seed is viable?
1. Physical Appearance

One of the most common ways to assess seed viability is by examining its physical characteristics. Healthy cannabis seeds usually share several key visual traits:

  • Color: Viable cannabis seeds are typically dark in color—shades of brown, gray, or even black. Immature seeds often appear pale green or whitish and are unlikely to germinate.
  • Pattern: A viable seed may have tiger-like stripes or mottled patterns. Though not a strict indicator, these patterns are common in mature seeds.
  • Sheen: A slight, waxy sheen often indicates a healthy outer shell. Dull or chalky-looking seeds may be old or underdeveloped.
how can i tell if a cannabis seed is viable appea
2. Size and Shape

Healthy cannabis seeds are generally:

  • Medium to large in size.
  • Oval or teardrop-shaped.
  • Symmetrical.

Seeds that are small, misshapen, or asymmetrical may not be viable, though some exceptions exist depending on the strain.

3. Hardness and Shell Integrity

A gentle squeeze test can help identify a viable seed:

  • Hold the seed between your thumb and forefinger.
  • Apply slight pressure.

A viable seed should feel firm and resist pressure. If it cracks, crumbles, or collapses, it is likely non-viable. However, excessive force can also damage a healthy seed, so be gentle.

4. Float Test (Water Test)

The float test is a practical method, especially if you’re uncertain about a seed’s viability:

how can i tell if a cannabis seed is viable wt
  • Fill a glass with lukewarm distilled water.
  • Drop the seeds in and wait 1–2 hours.

Interpretation:

  • Sinks: Usually a good sign that the seed is dense and viable.
  • Floats: Often indicates low density and possibly non-viable.

Note: Do not leave seeds in water longer than 24 hours, as prolonged soaking may trigger premature germination or rot.

5. Germination Test

If you’re unsure about visual or tactile signs, the most definitive way to check viability is to attempt germination:

  • Place seeds between damp (not soaking wet) paper towels.
  • Store them in a dark, warm (70–85°F or 21–29°C) environment.
  • Check daily.

Viable seeds will usually sprout a taproot within 2–7 days. If a seed hasn’t germinated after 10 days, it is likely non-viable.

6. Age and Storage Conditions

Seed viability diminishes over time, especially if stored improperly. Factors affecting seed longevity include:

  • Temperature: Seeds should be stored in a cool environment (e.g., refrigerator).
  • Humidity: High humidity can cause mold or early sprouting. Seeds do best in dry conditions (less than 10% relative humidity).
  • Light: Exposure to light can degrade seed quality. Keep seeds in an airtight, dark container.

Properly stored cannabis seeds can remain viable for 3–5 years or longer. Old seeds may still germinate, but success rates drop over time.

7. Genetics and Source Quality

Viability also depends on the source. Seeds from reputable breeders or seed banks are far more likely to be viable than random bag seeds (seeds found in purchased cannabis flowers). Breeders selectively choose mature, healthy seeds, often with documented germination rates.

8. Laboratory Testing (Advanced)

Professional cultivators may opt for lab testing, including:

  • X-ray scanning: To visualize internal seed structure.
  • Tetrazolium tests: Chemical staining techniques to assess seed viability.

These are rarely needed for home growers but are used in commercial agriculture and breeding programs.

Summary Checklist

To tell if a cannabis seed is viable:

  1. Color: Dark and mottled.
  2. Shape: Oval, symmetrical.
  3. Hardness: Firm when gently squeezed.
  4. Float Test: Sinks in water.
  5. Germination: Sprouts within 2–7 days.
  6. Storage: Kept cool, dark, and dry.
  7. Source: Bought from reputable suppliers.
Final Thoughts

While no single test guarantees 100% accuracy, combining multiple methods increases your chances of identifying viable cannabis seeds. Experienced growers often rely on a mix of visual inspection, float testing, and germination trials to decide which seeds to plant. Taking the time to check seed viability up front helps ensure a productive and satisfying growing experience.