After more than 30 years starting seeds indoors—from tomatoes and peppers to brassicas and herbs—I’ve learned that you don’t need fancy equipment, but you do need the right foundational supplies. The right tools make seed starting easier, more consistent, and far more successful.

Here are the seed-starting supplies I rely on every year in my Sonoma Valley garden, along with my tips for choosing the best options.

Seed-Starting Mix

A fine-textured, sterile seed-starting mix is essential. Avoid heavy garden soil indoors—it compacts and harbors disease.

What I use: A peat- or coir-based mix with added perlite for drainage.

Why it matters:

Prevents damping-off
Holds moisture without getting soggy
Allows delicate roots to grow freely

Seed Trays & Containers

You can start seeds in just about anything, but reusable seed trays and cell packs make the process cleaner and more efficient.

Best options:

Cell trays (40, 50, or 72 cells) for most vegetables
3–4 inch pots for large seeds (squash, cucumbers) or potting up
Soil-block makers if you prefer plastic-free

My experience:
I use 72-cell trays for my early sowings because they fit easily under lights and transplant well.

Humidity Domes

Humidity domes hold moisture and warmth during germination.

Tips:

Remove the dome as soon as seedlings sprout
Vent daily to prevent fungal issues

Humidity domes give consistent germination—especially helpful for slow sprouters like parsley or peppers.

Heat Mat

A heat mat is one of the few “optional” tools I consider essential for warm-season crops.

Why I use it:

Speeds germination dramatically
Improves consistency for tomatoes, peppers, eggplants
Keeps soil at 70–75°F—ideal for most seeds

Cool-season crops (lettuce, brassicas) often germinate fine without it.

Grow Lights

Windows alone rarely provide enough light for strong seedlings. After decades of trial and error, high-quality LED shop lights or grow lights offer the best results.

Light placement:

2–4 inches above seedlings
14–16 hours per day on a timer

Good lighting prevents leggy seedlings—one of the most common beginner issues.

Labels

You think you’ll remember what you planted—until everything sprouts at once. Labels save frustration.

What I like:

Plastic tags for trays
A wax pencil or fine-tip marker that won’t fade

Spray Bottle or Fine Watering Can

Gentle watering is key to avoiding seed displacement.

My approach:

Use a spray bottle early
Switch to bottom watering trays once seedlings grow

This keeps stems dry and reduces disease risk.

Fertilizer

Seedlings don’t need fertilizer until the first true leaves appear. When they do, I use:

• A half-strength organic liquid fertilizer
Feed every 10–14 days for steady, healthy growth.

Fan for Air Circulation

A small tabletop fan strengthens stems and reduces fungal pressure.

How I use it:

Low setting
A few hours each day
Pointed near seedlings, not directly at them

Optional But Helpful

Seedling heat mat thermostat for precision
Boot trays under seed trays to collect water
Shelving units to organize large seed-starting setups

Final Thoughts

With the right seed-starting supplies—and just a bit of practice—you can grow vigorous, transplant-ready seedlings every year. Over time, you’ll customize your setup based on the crops you grow most often, but these essentials will give you a dependable foundation.

Seed-Starting Shopping List