A seed-starting setup on a budget: what you need and the true cost per plant

By FarmerTested · a network of working growers based in Waxhaw, NC

Links marked "on Amazon" in this guide are affiliate links. As an Amazon Associate I earn from qualifying purchases, at no extra cost to you. True Leaf Market and Botanical Interests links are affiliate links through Awin. Links to other stores are coming as those programs approve us. Commissions never change what I recommend, and I haven't tested these specific products. Full disclosure

Walk into a garden center in February and you'll find seed-starting kits with domes, pellets, little greenhouses and lights shaped like spaceships. Most of it works. A lot of it isn't necessary. Starting seeds is one of the cheapest ways to grow your own food, as long as you buy the few things that matter and skip the rest.

This guide covers what each piece does, what you can skip, and what a basic setup costs per seedling once you spread it over a few seasons. That's the same true-cost approach I use for the hydroponic systems on this site.

A note on the prices

The prices below are round example numbers, not quotes, and not Amazon prices. They're there so you can follow the math. If you follow one of our Amazon links, check the current price there before you buy. Prices change every season. When I swap in real product links, I'll replace these with sourced, dated prices the way I do on the comparison table. Plug in what you actually pay and the method still works.

What you actually need

1. Trays and cell inserts

The standard is a "1020" flat (about 10 by 20 inches) with a cell insert dropped inside. A 72-cell insert is a good all-purpose size for lettuce, brassicas and onions. Tomatoes and peppers are happier with bigger cells or a later move into small pots. Buy sturdy trays. Thin ones crack after a season and spill water every time you lift them, and the heavy-duty kind lasts for years. (see heavy-duty 1020 trays with 72-cell inserts on Amazon)

A clear humidity dome helps hold moisture until seeds germinate. Take it off once most of the tray has sprouted, or you'll invite damping-off, the fungus that topples seedlings at the soil line. (see humidity domes for 1020 trays on Amazon)

2. Seed-starting mix (not garden soil)

Use a soilless seed-starting mix, usually peat or coir with perlite or vermiculite. It's fine-textured, drains well and starts out free of weed seeds and most disease. Garden soil and bagged topsoil pack down in a cell, stay soggy and bring problems with them. On the farm I care a lot about building soil, but a seedling tray is not the place for it. (see soilless seed-starting mix on Amazon)

Wet the mix before you fill the cells. Dry peat repels water, and a dry-filled tray will float your seeds away on the first watering.

3. A light

This is the one piece you can't skip. A sunny windowsill in a Carolina February doesn't give seedlings nearly enough light. They stretch toward the glass and end up tall, pale and floppy. An inexpensive LED shop light hung a few inches above the tray beats the brightest window in the house. I wrote a separate guide on how much light seedlings need and how far away to hang it. (see full-spectrum LED shop lights on Amazon)

4. An outlet timer

Seedlings want a steady day length, usually 14–16 hours. You will forget to turn the light off, so a cheap plug-in timer pays for itself in plants that don't get cooked or starved. (see plug-in outlet timers on Amazon)

5. A heat mat (for some crops)

Peppers, eggplant and tomatoes germinate faster and more evenly in warm mix. A seedling heat mat under the tray raises the mix temperature above a cool room. Lettuce, onions and brassicas don't need it, and lettuce can germinate poorly when it's too warm. Move the tray off the mat once seeds are up. (see seedling heat mats on Amazon)

6. Labels and a pencil

You think you'll remember which tray is which. You won't. Write the variety and sow date on every label, in pencil, because marker fades under lights. (see plant labels on Amazon)

7. Seed

Buy from a company that dates its packets and lists germination info. A packet of lettuce or tomato seed holds far more seed than one household will sow in a season, so seed is a small line item per plant. True Leaf Market is one option with dated packets and a wide organic garden seed list. Botanical Interests organic seeds is another.

Nice to have, but skip at first

• A small fan. A gentle breeze makes stems sturdier and helps against damping-off. Any desk fan on low works.
• A shelving rack. Useful once you're running more than two trays.
• Peat pellets and all-in-one kits. Convenient, but you pay for that convenience every season.
• A thermostat for the heat mat. Worth it if you start a lot of peppers. Otherwise, just watch the tray.

The true-cost math

Here's a basic two-tray setup with example prices. The durable gear lasts several seasons. The consumables get bought again every year.

Electricity (estimate): a 40 W light for 16 hours a day uses 0.64 kWh a day. Over about 60 days of seedling season, that's 38.4 kWh. A heat mat drawing an example 20 W for two weeks of germination adds about 6.7 kWh. That's about 45 kWh in total, or about $7 at $0.15/kWh. Your mat's wattage is on its label.

Spread over 3 years: $88 of durable gear ÷ 3 = about $29 a year. Add $40 of consumables and $7 of power, and the setup runs about $76 a year.

Per plant: two 72-cell inserts hold 144 seedlings. Assume you run a spring round and a fall round and end up with 200 transplants you actually use (my assumption, since not every cell germinates or gets planted). That comes to about $0.38 per transplant. Even in year one, with all the gear bought at once, it's about $0.68 per transplant ($135 ÷ 200).

Formula: true cost per year = durable gear ÷ years kept + yearly consumables + electricity. Per plant = true cost per year ÷ transplants you actually use. All prices here are labeled examples.

Compare that with what you pay for a single potted vegetable transplant at a garden center this spring, and the trays pay for themselves quickly. They also let you grow varieties the garden center doesn't carry.

How this compares with a home hydroponic system

A seed tray and a hydroponic tower solve different problems. Trays make cheap transplants for the garden. A tower is meant to produce the food itself, indoors and year-round. Still, the per-plant comparison is useful. Pod-based systems charge roughly $2 to $5 per pre-seeded pod (see our countertop garden breakdown), while open systems let you start your own seed for pennies. If you already have a tray setup, an open system that takes your own plugs is much cheaper to feed. I'll be testing that myself once I buy my first system.

A farmer's checklist

• Pre-moisten the mix. Fill the cells, tap the tray down, and sow at the depth on the packet.
• Dome on and heat mat on for warm-season crops until germination. Then take the dome off and move the tray off the mat.
• Light on a timer, 14–16 hours, hung close.
• Water from below once the surface dries. Don't keep the mix soaking wet.
• Start a gentle feed once true leaves appear, and pot up anything that outgrows its cell.

Not sure when to sow what? Start with the Piedmont seed-starting calendar.

More seed-starting guides

• When to start seeds in the NC Piedmont: a calendar for zone 7b
• A seed-starting setup on a budget: what you need and the true cost
• Grow lights for seedlings, explained: PPFD, hours and distance
• Starting seeds for hydroponic towers vs soil: rockwool, plugs and sponges