Beginner's Guide to Seedlings

1. Gather your supplies


You’ll need:

  • Seeds
  • Containers: seed trays, cell packs, peat pots, or clean yogurt cups (with drainage holes)
  • Seed-starting mix (lighter than regular potting soil)
  • Water (spray bottle or gentle watering can)
  • Light source: grow lights will be needed; sunny windows typically do not have enough light

2. Use the right soil

  • Fill containers with moist seed-starting mix or a light potting mix
  • Gently press the soil down—don’t pack it tightly (again, try to get things light and fluffy)
  • Seed-starting mix helps prevent disease and allows tiny roots to grow easily

3. Plant the seeds

  • Some seeds require stratification before germination.  If your seeds require this, please refer to the instructions here.  Without proper stratification, seeds will have zero or little germination.
  • Check the seed packet for planting depth
    • Tiny seeds: press onto the soil surface
    • Larger seeds: plant about 2–3× as deep as the seed is large
  • Cover lightly with soil,  or not at all if seeds need light to germinate

4. Water gently

  • Mist or water from the bottom to avoid washing seeds away
  • Soil should be moist, not soggy
  • Good drainage is essential

5. Provide warmth

  • Most seeds germinate best at 65–75°F (18–24°C). Determine the temperature at which your seeds germinate best.  The wrong temperature can easily affect germination rates and times.
  • A warm room or a seedling heat mat may be used if additional heat is needed.  We also use our oven-proofing drawer (85°F) as needed.

6. Give plenty of light

  • Once seedlings emerge, ensure seedlings are:
    • Under grow lights 2–3 inches above plants
    • Give seedlings 12–16 hours of light per day

7. Care for seedlings

  • Water when the soil surface feels dry
  • Thin seedlings by snipping extras at the soil level
  • After a few weeks, feed lightly with diluted liquid fertilizer if using a seed-starting mix.
  • Ensure the seedling area has good airflow to prevent damping-off.  A fan or a room with forced-air heating/cooling can make a significant difference.  Basements without airflow are prone to seedlings damping-off.

8. Harden off before planting outside

  • About 1–2 weeks before transplanting:
  • Start with 1–2 hours outdoors in shade
  • Gradually increase sun and time outside each day
  • Protect from wind and frost

Common beginner mistakes to avoid

  • Too little light → leggy seedlings
  • Overwatering → mold, root rot, damping off (also caused by too little airflow)
  • Planting too early → plants outgrow containers and are hard to manage