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Seed Starting on soil

soil with seed starting

What's Happening

Seedlings require consistent moisture for germination but are highly vulnerable to damping-off disease—a fungal condition (Pythium, Rhizoctonia, Fusarium) that attacks the stem at soil level and causes collapse. Standard potting mix contains fungal spores and lacks the fine, light texture needed for delicate root penetration. Dense soil also creates anaerobic conditions around germinating seeds that inhibit cellular respiration required for embryo development and early root growth.

How to Fix It

  1. 1

    Prepare sterile mix: Combine 5 parts fine peat, 3 parts perlite, 2 parts vermiculite

  2. 2

    Sterilize medium: Bake at 180°F for 30 minutes or microwave in covered container until steaming

  3. 3

    Fill shallow trays: Use 2-3 inch deep containers—excess soil depth is unnecessary for seedlings

  4. 4

    Sow and cover: Plant seeds at depth 2x their size, mist surface lightly, cover with humidity dome

  5. 5

    Bottom-water only: Place tray in 1 inch water until surface glistens—prevents surface fungal growth

  6. 6

    Provide bottom heat: Maintain 70-75°F for warm-season crops, 60-65°F for cool-season varieties

How to Prevent It

Formulate seed starting mix with 50% fine peat or coco coir (moisture retention), 30% perlite (aeration), and 20% vermiculite (nutrient holding). Sterilize mix by baking at 180°F for 30 minutes or microwave until steaming to kill fungal spores. Use shallow trays with clear domes to maintain 80-90% humidity. Bottom-water only to prevent surface saturation that promotes damping-off.

Related Problems

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Frequently Asked Questions

What causes seed starting on my plant?
Seedlings require consistent moisture for germination but are highly vulnerable to damping-off disease—a fungal condition (Pythium, Rhizoctonia, Fusarium) that attacks the stem at soil level and cause...
How do I fix seed starting?
Prepare sterile mix: Combine 5 parts fine peat, 3 parts perlite, 2 parts vermiculite. Sterilize medium: Bake at 180°F for 30 minutes or microwave in covered container until steaming.
How do I prevent seed starting from happening again?
Formulate seed starting mix with 50% fine peat or coco coir (moisture retention), 30% perlite (aeration), and 20% vermiculite (nutrient holding). Sterilize mix by baking at 180°F for 30 minutes or mic...