Tomato Seed Starting & Planting Garden Guide

Our Store

Tomato Seed Starting

  • Start with fresh, sterile starting mix (Do Not use potting soil. It is too dense).
  • NOTE: Other good starting options: Jiffy-7® starter wafers, Coco Coir mats, or Coco Coir expandable pellets.

  • Pre-moisten the mix. It should not be soggy, and not dry.
  • Place trays onto proper heat mat with temperature setting at 75° to 85°F.
  • Pre-soak the seeds for 8 hours, which enhances germination results.
  • NOTE: Use warm water from the tap. Start soaking at night for sowing the next morning.

  • After soaking, rinse seeds with clean tap water, then sow at 1/4 inch deep.
  • NOTE: Tomato seeds do not need light to germinate. But seedlings require direct light.

  • Cover seeds lightly with additional mix or use vermiculite and spritz with water to moisten the top.
  • NOTE: Cover the tray with plastic wrap or a clear plastic dome.

  • Keep the mix moist with good air circulation.
  • Germination typically in 7 to 14 days. The warmer the soil, the quicker seeds can germinate.

After Germination

  • Once seeds are germinating:
    • Remove trays or pots from the heat mat.
    • Remove plastic wrap or dome.
    • Keep soil consistently moist by spritzing or applying water as needed.
    • Move trays or pots into bright light locations.
  • Room air temperature should be reduced by 8-10°F.
  • Rotate 180° each day to help prevent leaning & stretching.
  • NOTE: Tall, stretched seedlings mean they do not have enough light, the temperature is too high, or both.

Hardening Off Seedlings

  • 1 week to 10 days prior to planting outside, slowly adapt young plants to outside conditions.
  • During the nicest part of the day, set plants outside for 4 to 6 hours in a sheltered location with dappled sun.
  • Keep trays or pots up off the ground and out of strong breezes.
  • Maintain moist soil conditions during hardening off. Check for moisture when they go out and again when they come back in.

Garden Soil Prep

  • Vegetables, including tomatoes, prefer well-drained, organically rich, amended soils.
  • Apply low nitrogen (N), higher in phosphorus (P) & potassium (K) fertilizer to the garden beds, 2-4 weeks prior to planting out.
  • Add ample amounts of leaf compost or aged manure at the same time and work well.
  • Also work in 3 to 5 pounds of appropriate fertilizer per 100 square feet.
  • NOTE: Espoma Tomato-Tone 3-4-6 and Organic Healthy Grow Tomato & Veg. 3-3-6 both have additional micronutrients tomatoes need like calcium (CA).

Proper Plant Spacing

The most important aspect of proper spacing is to help prevent disease disasters.

  • In cages, indeterminate plants should be planted 2.5 to 3 feet apart with 4 feet between rows.
  • Determinate should be planted 2 to 2.5 feet apart with 3 feet row spacing. May or may not require cages.