Walk into any garden center in May and you can have a full garden planted by afternoon — no seed trays, no grow lights, no schedule to keep. Or you could have started seeds in February for a fraction of the cost and twice the variety. Both approaches work. Which is better depends on your situation, your crops, and how much you enjoy the process.
The True Cost Comparison
A 6-pack of tomato transplants at a garden center costs $5–10 and gives you 6 plants of one variety. A packet of tomato seeds costs $3–4 and contains 25–50 seeds — enough for years of planting with dozens of variety choices. The savings are real, especially for crops where you want quantity. But there's overhead: a basic seed-starting setup (trays, seed-starting mix, grow lights) costs $50–150 upfront. Grow lights in particular are the main cost. If you're starting just a few trays per year, transplants can be more cost-effective until the equipment pays for itself.
What Benefits from Indoor Starting
Tomatoes, peppers, and eggplant need 6–10 weeks of indoor growing before they're ready to transplant after your last frost. Without indoor starting, you'd lose 6–10 weeks of your growing season — and in colder climates (Zones 5–6), that can mean the difference between a harvest and none at all. Other crops that benefit from a head start: broccoli, cauliflower, cabbage, celery, and leeks, which also need 6–8 weeks indoors.
What Prefers Direct Sowing
Root vegetables — carrots, beets, radishes, parsnips, turnips — must be direct sown. Their roots are the crop; any transplanting disrupts root development and causes forking or deformity. Beans, peas, corn, squash, cucumbers, and melons also germinate so quickly outdoors that there's minimal advantage to indoor starting. These crops can go directly in the ground after your last frost. Check succession planting schedules to know exactly when to direct sow each crop in your garden.
When to Start by Zone
Your last frost date is the anchor. Work backward from it. In Zone 5 (last frost around May 15), start tomatoes in early to mid-March — 10 weeks before transplant date. In Zone 7 (last frost around April 15), start tomatoes in late January to early February. Peppers need an extra 2 weeks over tomatoes — add those to your starting date. Find your exact last frost date from your local extension service or USDA frost date maps. See our growing by zone guide for a breakdown by region.
Hardening Off: The Critical Bridge
This step is where many indoor-started seedlings are lost. Plants raised indoors haven't experienced direct sun, wind, or temperature swings. Moving them directly to the garden causes sunscald, wind damage, and transplant shock. Hardening off means gradually exposing seedlings to outdoor conditions over 7–10 days. Start with 2 hours of morning shade on day one. Add more time each day, gradually introducing direct sun. By day 10, plants can stay out all day. Skip or rush this process and you can lose weeks of growth to stressed or dead transplants.
The Variety Advantage of Seed Starting
Garden centers carry 5–10 popular varieties of each crop. Seed catalogs carry hundreds. If you want Brandywine tomatoes, Armenian cucumbers, Dragon Tongue beans, or any heirloom variety with particular flavor or growing characteristics, you'll likely need to grow from seed. This is the argument that converts most gardeners to seed-starting after their first season — not cost savings, but access to varieties that simply aren't sold as transplants.
Frequently Asked Questions
- Can I start seeds without a grow light?
- You can, but results are usually poor. A south-facing window provides 3–4 hours of useful light in winter and early spring — not enough for most seedlings. Without supplemental light, seedlings become leggy (elongated, weak stems) reaching for insufficient light. A basic 2-bulb fluorescent or LED shop light suspended 2–4 inches above seedlings makes an enormous difference.
- What soil should I use for starting seeds?
- Use seed-starting mix, not garden soil or potting mix. Seed-starting mix is finely textured, sterile, and drains well — conditions ideal for germination. Garden soil compacts in trays and may carry pathogens. Potting mix is often too coarse and nutrient-dense for fragile seedlings.
- How do I know when transplants from a store are ready to plant?
- Look for stocky stems (not leggy), healthy green color, and no signs of disease or pest damage. Check the root ball — it should be well-developed but not massively root-bound. Avoid transplants already in bloom if you can; they've been pushed to flower too early and need time to establish roots before focusing on fruit.
- What's "damping off" and how do I prevent it?
- Damping off is a fungal disease that collapses seedling stems at soil level. It's caused by overwatering, poor airflow, and contaminated soil. Use sterile seed-starting mix, water from below (set trays in water and let soil wick it up), and run a small fan near seedlings for airflow.
- How many seeds should I plant per cell?
- Two or three seeds per cell, then thin to one seedling once germination is confirmed. Thinning means snipping the extras at soil level, not pulling — pulling can disturb the roots of the seedling you're keeping.