You can start seeds indoors for under $20 using stuff you probably already own, like yogurt cups and a shop light. Here's the exact setup, timing by frost date, and the one mistake that kills most beginner seedlings.
You don't need a grow tent or heated mats to start seeds indoors. Save yogurt cups, egg cartons, or yogurt containers and poke 3-4 drainage holes in the bottom, or buy a 72-cell plastic tray for $3-5 at any garden center. Fill with seed-starting mix, not garden soil or regular potting soil, because garden soil compacts in small cells and often carries fungus that causes damping off, a disease that rots seedlings right at the soil line within days of sprouting.
Light is where most cheap setups fall apart. A sunny windowsill rarely gives enough light, and the seedlings respond by stretching tall and pale, called getting leggy, which weakens them permanently. Instead, hang a basic shop light (LED or fluorescent, around $10-15) just 2-3 inches above the seedlings, raising it as they grow, and run it 14-16 hours a day on a $10 outlet timer so you don't have to remember.
Timing depends on your last spring frost date, which you can look up for your zip code through your local cooperative extension office. Tomatoes, peppers, and eggplant need the most lead time: start them 6-8 weeks before your last frost. Lettuce, basil, and other quick herbs only need 4-6 weeks. Squash, cucumbers, and melons resent having their roots disturbed, so either direct-sow them outdoors after frost or start them in individual pots just 2-3 weeks before your transplant date.
Water from the bottom by setting the whole tray in an inch of water for 10-15 minutes, then let it drain, rather than pouring water over the top where it pools around stems and invites damping off. Keep soil moist but never soggy, and run a small fan nearby for an hour a day once seedlings emerge; the air movement strengthens stems and cuts down on fungal problems. If you're starting tomatoes, keep in mind the foliage is mildly toxic to cats and dogs, so set trays somewhere curious pets can't nibble.
Key Takeaways
- ✅ Reuse yogurt cups or buy a 72-cell tray for $3-5, always with drainage holes
- ✅ Use seed-starting mix, not garden soil, to avoid damping off fungus
- ✅ Hang a $10-15 shop light 2-3 inches above seedlings, 14-16 hours a day
- ✅ Start tomatoes/peppers 6-8 weeks before last frost; basil/lettuce 4-6 weeks
- ✅ Bottom-water in a shallow tray instead of soaking soil from above
- ✅ Tomato and pepper foliage is mildly toxic to cats and dogs
Timing in this guide is counted from the average last frost date. Frost dates are averages, so check your local date before you plant.