Seed Handling & Testing Guide

At Sigma Seeds, we treat seeds as living collectibles — genetic archives that require the right conditions to preserve their potential. Seeds can lose viability if they are mishandled, so following best practice is essential.

This page explains the correct way to store and test seeds so you can be confident in their quality.

 Storage Best Practice

  • Cool, Dark, Dry-  keep seeds away from light, heat, and moisture.

  • Airtight Containers-  use vials or sealed bags (with desiccant for long-term storage) to prevent humidity damage.

  • Stable Temperature-  avoid frequent changes (e.g., moving in and out of the fridge daily).

  • Heat is the enemy- For longer-term storage, keeping seeds in a fridge can extend viability, but they must be in a completely airtight container to avoid condensation when taken out.

  • Handle Carefully-  oils and moisture from fingers can reduce longevity; use clean, dry hands or tweezers.

 Testing Seeds for Viability

We batch-test seeds before release, but if you wish to test viability yourself, it’s important to do so under controlled conditions.

  • Use Distilled or pH-Balanced Water- tap water with chlorine or mineral imbalances can damage seeds.

  • Stable Temperatures-  seeds should be tested at consistent warmth (22-25c). Avoid cold snaps or hot fluctuations.

  • Avoid Over-Soaking- seeds should not be left in standing water for extended periods.

  • Paper Towel Method-  a clean, damp (not wet) medium in a sealed container is the standard way to observe viability.

It is imperative that you use the paper towel method for testing. No other method is supported.
This approach provides a controlled, observable environment that minimises variables such as excess moisture, temperature fluctuations, or contaminants. Using unapproved methods (such as soil or direct water soaking) introduces too many external factors, making results unreliable. For accuracy, claims regarding seed viability will only be considered when the paper towel method has been followed correctly.

–> [If unsure follow this step by step guide]

Unsupported Testing Methods

  • Direct Soil Planting
    Planting seeds straight into soil introduces uncontrolled variables (moisture levels, fungi, pests, soil compaction) and cannot provide reliable results for viability testing.

  • Glass of Water Method
    Leaving seeds submerged in water beyond the initial soak can drown or damage them, and results are inconsistent.

  • Peat Pellets / Peat Pots / Jiffy Pellets
    These hold too much water and create anaerobic conditions, leading to rot rather than a fair test of seed viability.

  • Rockwool Cubes
    pH instability and oversaturation make rockwool unsuitable for reliable viability testing.

  • Direct Outdoor Testing
    Exposure to fluctuating light, temperature, and humidity outdoors makes any test invalid.

  • Cotton Wool or Tissue (Non-Paper Towel)
    Cotton wool and some tissues stay too wet or break down, causing seeds to suffocate or rot rather than germinate.

 Why This Matters

Our Germination Guarantee is based on seeds being stored and tested correctly. If you raise a claim, we may ask for details about how the seeds were handled. This helps us determine whether the issue lies in the batch itself and ensures that no future collector faces the same problem.

By following the correct steps, you’ll be able to test viability fairly — and Sigma will always stand behind you when the protocol has been respected.

⚠️ Disclaimer

Claims regarding seed viability will only be considered valid if the approved paper towel method has been followed exactly. Any results obtained using unsupported methods (such as soil, water glasses, peat pellets, rockwool, or outdoor testing) cannot be accepted as evidence of non-viability.