Treated vs. Untreated Seeds: What's the Difference and Which Should You Choose?
by Paramount Seeds on Aug 04 2026
Understanding Seed Treatments
When you browse the Paramount Seeds catalog, you'll notice that each product listing specifies whether the seed is treated, untreated, or untreated and primed. This isn't just fine print — it's important information that affects how you handle, germinate, and grow your crop. Understanding the difference helps you make the right choice for your operation, your growing environment, and your market.
Disclaimer: Seed treatments are determined and applied by the original breeder or supplier — not by Paramount Seeds. We supply seed in the treatment form provided to us by the breeder. Growers are responsible for conducting their own research on any chemical seed treatments and ensuring compliance with local regulations, certifications, and safety requirements before use. The information in this article is provided for general guidance only and does not constitute agronomic or legal advice.
What Are Treated Seeds?
Treated seeds have been coated with a fungicide — most commonly Thiram (TMTD) or Fludioxonil — before packaging. The treatment is applied to the seed surface to protect it during germination and early establishment, when seedlings are most vulnerable to soil-borne fungal pathogens such as Pythium, Fusarium, and Rhizoctonia (damping-off).
Benefits of Treated Seeds
- Protection during germination: The fungicide creates a protective zone around the seed in the soil, reducing the risk of damping-off and early seedling loss.
- Better stand establishment: Particularly valuable in cool, wet, or high-humidity conditions where fungal pressure is elevated.
- Reduced need for soil drenches: The seed-applied treatment can reduce or eliminate the need for additional fungicide applications at germination.
- Consistent results: Growers in challenging environments often see more uniform germination and stand establishment with treated seed.
When to Choose Treated Seeds
Treated seeds are a strong choice when you are growing in conditions with high disease pressure, cool or wet soils, or when you have experienced damping-off problems in the past. They are commonly used in commercial greenhouse cucumber, pepper, and tomato production where consistent stand establishment is critical.
Examples from our catalog that are supplied as treated seed include Caiman F1 Beefsteak Tomato, Socrates F1 Mini Cucumber, and Bologna F1 Long Dutch Cucumber.
Important Handling Notes for Treated Seeds
Treated seeds are not suitable for organic production and should be handled with care. Always wear gloves when handling treated seed, avoid contact with skin and eyes, and keep treated seed away from food, feed, and water sources. Do not save or replant treated seed. Dispose of unused treated seed and packaging according to local regulations.
What Are Untreated Seeds?
Untreated seeds have not been coated with any fungicide or chemical treatment. They are the natural seed as harvested, cleaned, and processed — nothing added. The vast majority of tomato varieties in the Paramount Seeds catalog are supplied as untreated seed as standard.
Benefits of Untreated Seeds
- Suitable for organic production: Untreated seeds can be used in certified organic growing systems (always verify with your certifier).
- No chemical residues: Preferred by growers who want to minimize chemical inputs or who are growing for markets that require clean-label production.
- Safe handling: No special precautions required beyond standard good hygiene practices.
- Flexibility: Can be used with any seed treatment or biological seed dressing of your choice if additional protection is desired.
When to Choose Untreated Seeds
Untreated seeds are ideal for organic growers, growers with well-managed, disease-free growing media, and operations using sterilized or pasteurized substrates where soil-borne pathogen pressure is low. They are also the right choice when your certifying body requires untreated seed.
The majority of our specialty tomato varieties — including Darkmoon F1, Snow Sweet F1, Tobrossa F1, and many others — are supplied as untreated seed as standard.
What Is Primed Seed?
Primed seed is a third category that often causes confusion. Priming is a pre-germination treatment — not as such, a chemical fungicide treatment — in which seeds are hydrated to a controlled level that initiates the early stages of germination, then carefully dried back before packaging. The result is a seed that is physiologically "ready to go" and will germinate faster and more uniformly than non-primed seed.
Benefits of Primed Seeds
- Faster germination: Primed seeds typically emerge 1–3 days earlier than non-primed equivalents.
- More uniform stands: Tighter germination windows mean more uniform seedling size, which simplifies transplanting and crop management.
- Better performance in stress conditions: Primed seeds often show improved germination under suboptimal temperature or moisture conditions.
- Still untreated: Primed seed carries no fungicide coating and is compatible with organic production (verify with your certifier).
Many of our tomato rootstock varieties and high-performance beefsteak tomatoes are supplied as untreated, primed seed as standard — including Maxifort F1 Tomato Rootstock, Estamino F1 Tomato Rootstock, Geronimo F1 Beefsteak Tomato, and Torero F1 Beefsteak Tomato.
What About Pelleted Seeds?
Some seeds in our catalog are also available as pelleted seed — where the seed is coated in an inert clay or similar material to create a uniform, round pellet. Pelleting makes small or irregularly shaped seeds easier to handle and sow, especially with mechanical seeders. Pelleted seed can be either treated or untreated. Examples include Maxifort F1 Rootstock (Pelleted) and Versai F1 Red Oakleaf Lettuce (Pelleted).
Quick Comparison
| Feature | Treated Seed | Untreated Seed | Primed Seed (Untreated) |
|---|---|---|---|
| Fungicide coating | ✅ Yes (Thiram/TMTD or Fludioxonil) | ❌ No | ❌ No |
| Organic compatible | ❌ No | ✅ Yes* | ✅ Yes* |
| Faster germination | Standard | Standard | ✅ Yes (1–3 days faster) |
| More uniform germination | Standard | Standard | ✅ Yes |
| Special handling required | ✅ Yes (gloves, disposal) | ❌ No | ❌ No |
| Best for high disease pressure | ✅ Yes | Depends on conditions | Depends on conditions |
*Always verify organic compatibility with your certifying body.
How to Know What You're Getting
Every product listing on the Paramount Seeds website states the seed treatment status in the product description. Look for phrases like:
- "Seed from this supplier is untreated as standard" — plain, untreated seed
- "Seed from this supplier is untreated, primed as standard" — untreated but physiologically primed
- "Seed from this supplier is fungicide treated as standard" or "Thiram treated (TMTD) as standard" — chemically treated seed
- "Untreated, primed and pelleted" — primed seed in pellet form
If you have questions about the treatment status of a specific variety or need guidance on which option is right for your growing system, don't hesitate to reach out to us. We're here to help you make the best choice for your crop.
Shop by Seed Type
Browse our full catalog to find the right variety and seed treatment for your operation. Whether you need the protection of a treated seed for a challenging environment, the clean-label appeal of untreated seed for an organic market, or the performance advantage of primed seed for a commercial greenhouse — Paramount Seeds has you covered.
Important Notice: Seed treatments are determined and applied by the original breeder or supplier, not by Paramount Seeds. Paramount Seeds supplies seed in the treatment form as received from the breeder. Growers are solely responsible for conducting their own due diligence regarding any chemical seed treatments, including reviewing safety data sheets, verifying regulatory compliance, and ensuring suitability for their specific growing system, market, and certification requirements. This article is intended for informational purposes only.