Master Seed Starting: A Complete Guide for Flower Farmers
I don’t know what I would do with my life during the winter months if I didn’t have seed sowing to look forward to! The dark, bleak days of winter leave lots of room for dreaming of the season to come, and seed starting is the beginning of making those dreams a reality.
This post will throw a lot at you—seed starting can get pretty complicated! For the sake of not overwhelming you, I’m going to focus on the basics while offering tips for aspiring professionals. Just know: that flowers want to grow. That’s always in our favor.
Note: This post contains affiliate links. If you make a purchase through these links, I may earn a small commission at no additional cost to you. Thank you for supporting our farm!
Dreaming of blooms: A glimpse of the seed varieties ready to start the season.
When to Order Seeds and Why You Should Be Seed Starting
Though seed catalogs begin pouring in come December and January, many of these are impulse purchases. For professional flower growers, most seeds should already be planned, ordered, and stored by November. Ordering in late summer and early fall ensures you have hard-to-find varieties on time and aligned with your sowing schedule. Winter can be reserved for refining plans and ordering trial varieties.
Seed starting is practical and economical for most flowers. Some varieties, like lisianthus, are exceptions due to their long growing cycles or specialized needs. For others, like sterile hybrids, starting from cuttings, tubers, or corms is preferable. But for the majority of crops, learning to grow from seed is essential.
To start successfully, think like a seed:
When does it typically germinate?
What conditions does it thrive in?
Does it prefer direct sowing or transplanting?
Seed packets and catalogs often provide this information. For seeds without instructions, such as those from Geoseed, I recommend taking detailed notes: sowing dates, conditions, germination timelines, transplanting, and bloom periods. Building your own data will allow you to refine your processes season by season.
Want to optimize your flower farming? Explore my blog on Advanced Crop Planning for strategies on succession planting, crop rotation, and efficient tracking systems.
To Direct Sow, Soil Block, or Start in Trays?
This decision depends on your setup and crop requirements. Some seeds, like sunflowers, thrive when directly sown. These plants often have taproots and resent disturbance or grow quickly enough that transplanting isn’t efficient. For small spaces, starting everything indoors may be necessary.
Direct Sowing: This saves time and materials but requires diligence in keeping the soil moist. Examples of flowers we direct sow include bachelor buttons, chamomile, larkspur, and bells of Ireland. Tools like the Jang seeder or handmade contraptions can speed up the process.
Soil Blocking vs. Trays: Soil blocking minimizes transplant shock and is excellent for sensitive varieties. It can be time-consuming and soil-intensive, so we’ve adopted a mixed approach. We use trays for faster-growing or less sensitive crops and soil blocks for those requiring a gentler touch.
For a deeper dive into soil-blocking, check out our Nitty Gritty Guide to Soil-Blocking, and explore our recommended soil-blocking kit here.
Preparing for success: Filling trays with Pro-Mix HP in our DIY propagation house.
Selecting the Right Substrate for Seed Starting
Seed starting requires a substrate, typically a soilless mix of peat moss or coconut coir with added perlite for drainage. A soilless mix reduces the risk of soil-borne diseases and pests, ensuring a healthier start for seedlings. It’s also light and fluffy, allowing young roots to establish easily. While many products are marketed as “seed-starting” mixes, we’ve found that high-quality substrates like ProMix HP perform excellently and are more versatile. ProMix HP, enriched with mycorrhizae for robust root development, is one of our top choices for seed starting. It’s typically easy to find at local nurseries, garden centers, or if you are looking for bulk you can find that here.
Peat Moss vs. Coconut Coir
Peat Moss: Affordable and widely available, peat moss retains water exceptionally well but is naturally acidic and less sustainable. It may require pH adjustments with lime and is more prone to mold and fungal growth if overwatered or used in poorly ventilated conditions.
Coconut Coir: Neutral in pH, eco-friendly, and a byproduct of the coconut industry, coconut coir drains well and rehydrates easily. It is pricier and may be harder to find locally but is less prone to mold compared to peat moss. However, it tends to retain salts, which can accumulate over time. To mitigate this, a yucca flush is beneficial to reduce salt buildup and support healthy root growth.
Regardless of the base, prioritize mixes with visible, quality perlite for improved drainage and aeration. Avoid lower-quality retail soils like Miracle-Gro, which often suffocate seedlings. If making your own mix, consider the trade-off in time, cost, and quality. Mixing soil incorrectly can lead to nutrient imbalances or drainage issues that harm your seedlings.
For growers interested in using coconut coir to create their own mix, check out this high-quality coconut coir here.
Versatile and durable: Filling Bootstrap Farmer Airprune trays to start the next round of seedlings.
Choosing Propagation Trays
Tray sizes (e.g., “72s” or “200s”) indicate the number of cells per standard 10”x20” tray. Tiny seeds, like snapdragons, fare better in smaller cells (128 or 200), while larger seeds like zinnias or cosmos benefit from larger cells (72 or 50).
Investing in durable trays reduces waste and saves money long-term. We’ve found deep root trays indispensable for sweet peas and other crops needing extra space.
For our favorite seed-starting trays, we recommend Bootstrap Farmer’s options—durable, versatile, and long-lasting. Check them out here.
For a comprehensive guide to essential seed-starting supplies, visit our blog for all the details.
How Stratification Impacts Germination Success
Some seeds require special treatments to germinate, as they are adapted to specific environmental triggers like cold temperatures or physical breakdowns. These treatments, known as stratification or scarification, help replicate the conditions seeds need to break dormancy and germinate successfully.
Cold Stratification: Mimics winter by exposing seeds to cold for 2-3 weeks. Larkspur and bells of Ireland often benefit from this but may germinate naturally in cool conditions.
Physical Stratification: Scarifying or soaking seeds can help break hard shells. Sweet peas, for example, can benefit from soaking to promote better germination.
For a comprehensive guide to stratification and how to time your seed starting effectively, visit our blog When to Plant: Frost Dates, Soil Temps, and Timing for Flower Farmers.
A peaceful sunrise illuminates the promise of a productive growing season in the propagation house. Over the years, we have upgraded it with vents, fans, and more- you can start simple!
Optimizing Your Seed Starting Setup: Greenhouses, Heat Mats, and Grow Lights
Starting seeds indoors often requires specialized equipment like grow lights, heat mats, and careful monitoring. If a greenhouse isn’t an option, a DIY germination chamber with proper lighting and ventilation can work effectively. Grow racks are another excellent, affordable solution for maximizing vertical space while ensuring seeds get the warmth and light they need. You can find reliable grow rack options here.
Grow Lights: Full-spectrum grow lights, which provide both red and blue light, are ideal for seedling development. These wavelengths support healthy growth and prevent legginess. Standard LEDs or fluorescent lights may not provide the same benefits, so investing in proper grow lights is worth considering.
Heat Mats: Using heat mats with a thermostat ensures consistent soil temperatures, which are especially beneficial for heat-loving crops like tomatoes or basil. A thermostat allows you to fine-tune the heat mat to the optimal range for each type of seed.
DIY Germination Chambers: You can create an effective DIY germination chamber using a shelving unit covered with plastic sheeting to trap warmth and humidity. Pair this with grow lights and heat mats for a compact and functional setup.
Ventilation: Proper air circulation is critical for preventing mold and damping-off. A small fan placed near your seedlings or regularly removing covers can help maintain airflow and reduce moisture buildup.
While we initially couldn’t afford a professional-grade propagation house, building our own was not only more affordable but also more durable than many pre-made kits. It proved to be a worthwhile investment, significantly improving our seed-starting process by saving time, reducing losses, and producing healthier seedlings.. However, the most important takeaway is to work with what you have—many successful growers begin with simple setups like grow racks or small chambers and upgrade as their resources grow.
Precision sowing: Iceland poppy seeds find their home with the help of simple tools.
Seed Starting Workflow
Sanitize trays/pots: Use warm water with a small amount of bleach, distilled vinegar, or dish soap to clean thoroughly. Rinse well and allow to air dry. This step is crucial to prevent disease and ensure healthy seedlings.
Moisten soil: Mix your substrate with warm water until it has the texture of a wrung-out sponge. Warm water helps activate any beneficial nutrients or mycorrhizae in the mix.
Fill trays: Gently scoop the moistened substrate into trays or pots, ensuring they’re filled to the top. Tap the tray on a hard surface to settle the soil and remove air pockets that can hinder root development. We even use same-celled trays to help slightly compact the substrate and ensure the cells are properly filled.
Label trays: Use durable tags and write with pencil, which won’t fade in the sun or smudge when wet. Include the variety name and sowing date. I like to label the sowing date in week numbers for easier planning and tracking, as discussed in my crop planning blogs.
Sow seeds: Place 1-2 seeds per cell or pot. For tiny seeds, use a bamboo skewer dipped in water to pick up and place seeds. Be careful not to bury seeds too deeply—a good rule of thumb is to plant seeds at a depth about twice their size. Some seeds require light to germinate and should not be covered at all, while others germinate better in darkness and benefit from a thin layer of substrate or vermiculite. Check seed packet instructions for specific requirements.
Cover seeds: Sprinkle a thin layer of substrate or vermiculite on top, depending on the seed’s requirements. Vermiculite helps retain moisture and suppress algae growth.
Place trays: Set trays in drip trays and cover with plastic domes if using. Position them on heat mats set to the appropriate temperature (typically 70°F for most crops) or place them in a greenhouse.
Monitor daily: Check for moisture levels and signs of germination. Bottom water trays to prevent displacing seeds, but avoid overwatering to reduce the risk of damping off. For pelleted seeds, a light misting or gentle overhead watering can help break down the seed coating and improve germination rates. I like using flood trays for bottom watering, as they make the process more efficient and consistent. You can explore high-quality flood trays from Bootstrap Farmer here.
Remove domes: Once about 50-70% of seedlings have germinated, you can remove plastic covers to increase airflow and prevent mold. The remaining seeds will continue to germinate as the optimal conditions have already been met. Ensure seedlings receive adequate light to avoid legginess. If using grow lights, position them close enough to prevent stretching but not so close that they risk overheating or burning the seedlings. A general rule is to keep lights 2-4 inches above the seedlings and adjust as they grow.
Fertilize: After two weeks, begin feeding with a diluted fertilizer. A mix of fish emulsion and kelp meal works well to provide gentle nutrients. Alternatively, you can use a pre-made seedling fertilizer like FoxFarm’s Big Bloom. Be cautious with nitrogen levels to avoid burning delicate seedlings—always dilute your fertilizer to half the recommended strength for young plants.
Harden off: Gradually acclimate seedlings to outdoor conditions by placing them in a shaded, protected area for increasing periods each day. Protect them from strong winds and harsh sunlight during this transition. Use low tunnels or frost cloth for added protection if needed.
When your seedlings are ready to transplant, take the next step with our blog, Transplanting Seedlings: A Step-by-Step Guide to Success, for practical tips and guidance.
Transplant: Once seedlings are strong and the weather permits, plant them out into prepared beds. Sensitive plants may benefit from additional measures like frost cloth or shade to ensure a smooth transition.
Facing challenges? Find solutions in our blog, Troubleshooting Seed Germination: Tips for Overcoming Common Issues.
The joy of the harvest: Golden hour and a bundle of freshly picked yarrow.
Final Thoughts
Seed starting is a foundational skill for every flower farmer, whether you're just beginning or refining your process. While there are many moving parts, the journey from seed to bloom is incredibly rewarding and well worth the effort. Remember, flowers are resilient and eager to grow, so don't be afraid to experiment and tailor techniques to your setup.
Keep detailed notes to track what works best, and don’t hesitate to explore new methods or tools that can enhance your results. Whether you're working with a DIY propagation setup or professional-grade equipment, the key is consistency and adaptability.
Happy growing!
We are looking forward to sharing more blooms with you soon.
Jessica & Graham
