Starting vegetables from seed is one of the most rewarding and cost-effective ways to grow a productive garden. With the right timing, tools, and know-how, you can raise strong, healthy seedlings indoors or sow directly outdoors for vigorous plants all season long. After more than 30 years of starting seeds year-round in Sonoma Valley—indoors under lights, in raised beds, mounded beds, and containers—I’ve learned the essential steps that guarantee success.

This guide is the foundation of the entire Seed Starting Learning Hub (see all of the Hub posts listed below). Whether you’re new to gardening or looking to sharpen your skills, start here.

Why Start Vegetables from Seed?

Starting from seed gives you:

More variety: Hundreds of options you won’t find as transplants.
Healthier plants: You control soil, temperature, light, and spacing.
Earlier harvests: Start cool-season crops early indoors and transplant.
Cost savings: A packet of seeds goes much further than nursery starts.

And perhaps most importantly: you gain a deeper understanding of how plants grow.

Seed Starting Indoors: When and Why to Use This Method

Indoor seed starting is ideal when you need a head start on the season—or when weather is too cold for direct sowing.

After decades of starting seedlings indoors for spring planting, here are the crops I consistently begin under lights:

Best Vegetables to Start Indoors

Tomatoes
Peppers
Eggplants
Basil
Broccoli
Cauliflower
Cabbage
Kale
Lettuce
Onions (from seed)
Herbs (most)

Warm-season crops need heat to germinate and time to mature. Cool-season crops benefit from early indoor growth so they’re ready to transplant as soon as the soil can be worked.

What You Need for Indoor Success

From my experience, these essentials make the biggest difference:

Seed starting mix — fine-textured, sterile, moisture-retentive.
Cell trays or pots — with good drainage and bottom-watering capability.
Grow lights — kept 2–4 inches above seedlings to prevent legginess.
Heat mat (optional) — speeds germination for warm-season crops.
Humidity dome — for germination, removed once seedlings emerge.
Consistent moisture — moist, never soggy.

My Indoor Seed Starting Method

Fill trays with moist seed-starting mix.
Sow seeds at the recommended depth (usually 2–3 times the seed’s diameter).
Cover lightly and mist.
Place trays on a heat mat until germination for warm crops.
Move under lights immediately when sprouts appear.
Keep lights close and run them 14–16 hours per day.
Bottom-water to avoid damping-off disease.
Thin seedlings to the strongest plant once true leaves appear.

After 30+ years, this method consistently produces sturdy, compact seedlings ready for transplanting.

Seed Starting Outdoors: When and Why to Direct Sow

Outdoor seed starting—direct sowing—means planting seeds right where they will grow. Many vegetables resent transplanting or simply grow better when started outdoors in native soil.

Best Vegetables to Direct Sow Outdoors

In my Sonoma garden, I always direct sow:

Beans
Peas
Corn
Cucumbers
Melons
Squash (summer and winter)
Beets
Carrots
Radishes
Turnips
Spinach
Swiss chard
Arugula
Cilantro and dill

Direct sowing avoids transplant shock and lets these crops establish strong taproots.

Outdoor Sowing Essentials

Through years of practice, these steps ensure reliable germination:

Prepare the soil well — loose, crumbly, and free of clods or crusting.
Rake smooth and water the bed before planting.
Mark rows or furrows to keep sowing even.
Sow seeds at the correct depth for fast, even germination.
Keep soil moist — a light mulch or row cover helps retain moisture.
Use shade cloth during hot spells to protect emerging seedlings.
Protect from birds and critters with row covers when needed.

My Outdoor Starting Tip

In Sonoma’s dry summers, I often lay a wooden board or shingle over freshly seeded rows for 2–4 days. This prevents crusting and keeps the soil moist. As soon as I see germination, I remove the board.

Should You Start Seeds Indoors or Outdoors?

Use this quick decision guide:

Start Indoors If:

The crop needs a long growing season
The weather is too cold for germination
You want extra-early harvests
You need precise temperature and moisture control

Direct Sow Outdoors If:

The crop grows a taproot
It dislikes root disturbance
Soil warms early in your climate
The crop germinates quickly (radishes, beans, greens)

When in doubt: look at the seed packet’s “indoors/outdoors” recommendations and match them to your climate and frost dates.

Timing: The Critical Key to Seed Starting Success

Starting seeds too early leads to weak, leggy seedlings. Starting too late delays your harvest.

For accuracy:

Know your last spring frost date.
Know your first fall frost date.
Work backward using your seed packet’s recommendations.

I’ve created a complete Seed Starting Calendar to help with timing—linked from this Hub.

Caring for Seedlings: Light, Water, and Airflow

Strong seedlings depend on consistent care.

Light

Keep lights 2–4 inches above seedlings.
Run them 14–16 hours per day.

Water

Bottom-water to reduce disease risk.
Keep soil evenly moist, not saturated.

Airflow

Use a small fan to strengthen stems.
Remove humidity domes after germination.

Good airflow has prevented countless damping-off cases in my own greenhouse.

Troubleshooting: Avoiding Common Seed Starting Problems

Leggy Seedlings

Cause: insufficient light, too much heat, or overcrowding.
Fix: lower lights, reduce temperature, space seedlings.

Damping-Off

Cause: overwatering, poor airflow, contaminated soil.
Fix: bottom-water, improve ventilation, use sterile mix.

Slow or Uneven Germination

Cause: incorrect temperature or planting depth.
Fix: use a heat mat for warm-season crops; recheck depth.

Seedling Collapse or Wilting

Cause: underwatering or overwatering.
Fix: consistent moisture; check drainage.

My Seed Starting Philosophy

After starting thousands of seeds every year in my Sonoma Valley garden, my core belief is this:

Seed starting is simple when you understand what the seed needs.
Warmth → Moisture → Light → Airflow.

Give each in the right balance, and the seed will do the rest.

Seed Starting Basics: A Complete Beginner-to-Advanced Guide for Indoor and Outdoor Seed Starting

Why Start Vegetables from Seed?