Examples › Gardening
🌱 Gardening

How to Start Tomatoes from Seed Indoors (6-Week Plan)

6–8 weeks seed to transplant $25–$50 (reusable supplies last for years) Beginner via YouTube Shorts

Summary

Starting tomatoes from seed is far cheaper than buying transplants (seeds cost $3–$5 for 30 plants vs $5–$8 per plant at a nursery) and gives you access to 300+ heirloom varieties. This 6-week plan covers: timing, soil mix, sowing depth, bottom heat, lighting, first transplant, hardening off, and garden planting.

Goal

Produce healthy, stocky tomato transplants ready to go into the garden after all frost risk has passed — with multiple varieties and zero damping-off.

Step-by-step Guide

1

Timing — count back from your last frost date

2

Gather your supplies

3

Fill cells and sow seeds

4

Germinate with bottom heat

5

Move under lights immediately after sprouting

6

Water correctly

7

Thin to one plant per cell at true-leaf stage

8

Pot up to 4" pots at 3–4 weeks

9

Harden off for 1 week before planting out

Tools & Materials

Item Estimated Cost
72-cell seed tray with dome $8
Seed-starting mix $8
Seedling heat mat $20
LED grow light (T5 or full-spectrum) $30–$60
Outlet timer (for grow light) $8
Tomato seeds (1–3 varieties) $3–$10
Estimated total $25–$50 (reusable supplies last for years)

Safety & Legal Warnings

Damping-off is a fungal disease that kills seedlings at the soil line. Prevention: bottom water only, good air circulation, don't overwater, use sterile seed-starting mix.
Do NOT plant tomatoes outside until all frost risk has passed — even a light frost will kill them.
Hardening off is mandatory. Tender indoor plants placed directly into full sun will sunscald and stall.

Troubleshooting

Problem

Seedlings are tall and floppy (leggy)

Fix

Light was too far away or hours too short. Lower the light to 2" above canopy. You can pot up and bury the leggy stem to compensate.

Problem

Seedlings dying at the soil line (damping-off)

Fix

Fungal. Remove affected seedlings immediately. Improve air circulation (small fan), reduce watering frequency, water from the bottom only.

Problem

No germination after 2 weeks

Fix

Check soil temperature — may be too cold. Verify seeds aren't too old (most seeds are viable 3–5 years). Try a fresh seed batch or check germination rate by placing 5 seeds on a damp paper towel.

What the Video Didn't Cover

Fertilizing seedlings: seed-starting mix has no nutrients. Start a diluted liquid fertilizer (half strength) once seedlings have their first true leaves.
Determinate vs indeterminate varieties behave differently in the garden — indeterminate types need caging or staking.

Related Resources

  • Old Farmer's Almanac frost date tool (almanac.com)
  • Epic Tomatoes by Craig LeHoullier — definitive heirloom variety guide
  • r/vegetablegardening — seed starting megathread (pinned each January)

Turn your video into a guide like this

Paste any TikTok, Reel, YouTube Short, Facebook, X, or Pinterest link. FullStep generates the full guide in about 30 seconds.

Get founder pricing Join the waitlist

← Browse all example guides