How to Start Plants from Seeds - Complete Tutorial

Here's an easy step-by-step guide for how to start plants from seeds to save money and have the varieties you want - and when you want - to plant them in your garden. It's the best thing you can do for your garden!

You can find even more seed starting information in our Seed Starting Guide.

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Let's start some seeds!

In this installment of the Vegetable Garden 101 series I'm going to share how to start plants from seeds indoors, weeks or even months before your planting season.

Growing your own plants from seeds is how you can have seedlings ready when it's time to plant in your area, saving money and by-passing the stores.

Even more importantly, they will be available when you are ready to plant on your timetable, throughout the whole season, not just in spring.

Is this seed starting tutorial only for vegetable seeds?

Even though this is part of a vegetable gardening series, the basic steps outlined here to grow plants from seeds work for any seeds, whether they are vegetables or flowers.

In fact, I often grow flower seedlings right along with my vegetables. My favorite flowers to grow indoors from seed include:

• marigolds
• cosmos
• snapdragons
• zinnias (they get a head start on blooming when planted early indoors)

Whether you're growing vegetables or flowers, it's so rewarding to see those first sprouts, knowing they will become the food your family will be eating in a few months, or blooms gracing your table.

Why should I start plants from seed?

I explained this more fully in this article about the big four reasons why it's a great idea, but the brief recap is:

• To save money.
• For control and selection.
• To have the best growing dates for your garden.
• It's fun!

It's not hard to start seeds, but it always helps to have pictures, so I'm sharing this complete tutorial on how to start plants from seeds, step by step, using the simple technique that I've used for years.

And, I don't leave you hanging - the other parts of this series include how to take care of your seedlings and how to plant them.

So yes, lets grow some plants from seeds!

How to Start Plants From Seeds

Basic Supplies To Start Seeds

• Seeds. Buying from online catalogs will give you the best selection and quality, but there's nothing wrong with buying from the store, as long as it's from a quality seed brand. Another benefit of catalogs: there's a TON of growing information in them, so you can learn a lot, too. Go here to see a list of catalogs I like to buy from.
• Grow light or a basic shop light with 2 fluorescent lights, one warm & one cool. I've always used the basic shop light set up at about half the price of 'official' grow lights and it's worked great. Make sure they have chains or ropes so you can raise and lower to lights to be right over the seedlings as they grow.
• Plastic planting tray unit with a clear dome which last a number of years. I  find planting in cells much easier than just laying the seeds in flat trays filled with soil - there's less thinning needed and less root disturbance when planting. You can buy the trays without the 6-cell pots, too, and fill them with reused 4-inch nursery pots (18 fit perfectly) to fill them (you can see this pictured above in the back left tray). The larger pots are great for peppers and tomatoes which need to grow pretty big before being planted - it means one less transplant to do.

PRO TIP: To reused plastic pots and cells, wash them out yearly with a good spray of water. Some say to use bleach, but I don't like using it and have never had a problem with fungus issues since I use sterilized potting soil.

PRO TIP 2: I don't recommend the "Jiffy Pots" type of trays or pots you may see in stores - they dry out faster and actually stunted the growth of some of my plants when I planted them directly into the garden as instructed. The roots weren't able to grow through the membrane and became root-bound. If you do use them, tear off the pot before planting.

• Sterilized seed starting potting mix. This is usually a soil-less mix that's made especially for starting seeds. I've never skimped by trying to reuse old soil since that's one of the ways to introduce a fungus to your seedlings. A quality seed starting mix is the basis of great seedlings, so it's worth the (slight) extra cost. Some potting mixes even include extra nutrients or fertilizers (though I recommend organic) to give your seeds a boost.
• Plastic garden labels - this link is to my favorite labels- not too big so they fit in the trays, easy to read, and last a number of years.
• Garden marker pen (while you can use a Sharpie pen if it's all you have, it probably won't last the season outside, though it will do fine while inside). Every time I think I will save time by not labeling every single plant cell, I am sorry. You will want to know what you loved so that you will be sure to grow it again AND you will want to know what not to plant again!
• Old mixing bowl or container for wetting soil.
• Large spoon or soil scoop for mixing and filling cells.
• Chopstick or small tool for making shallow indentations, plus small spoon for planting small seeds.

How to Plant Seeds Indoors

1. Gather seeds to plant.

Read the backs of the seed packets to find when to start indoors according to your last frost date and when you want to plant out in your garden (it may be different if you are using covers in the garden and you can plant earlier - again, another great reason to start your own seeds).

Plan how many of each seed variety you want and have room for. (HUGE TIP: start small - you probably don't want 12 heads of broccoli all at once...)

2. Wet the seed mix.

If you put it directly in the cells and then try to wet it, the centers will still be dry and you'll have to stir each individual pot, which is not easy. I have learned this the hard way - always wet the seed mix first.

(Update: Even though I see a lot of online tutorials showing the dry mix being planted in and just misted with water - don't do it! It will dry out inside and you won't get good germination. You will need to have drainage.)

Use a large bowl or container, fill it with starting mix, and add water. It takes awhile to get it thoroughly mixed, depending on your mixture. Which is why some people add the mix dry to the cells - it's easier to spread. But don't do that - trust me on this, okay?

3. Push the wet mix into the potting tray cells, tamping down to firm.

The soil will probably be somewhat clumpy, and may not go into the cells nicely for you, so don't be afraid to get dirty!

Fill the cells/pots full, because when you water them the dirt will sink a bit and you want as much soil as possible for your little seedlings.

4. Make labels and place in trays.

Use the marker to write what seed variety will be in the cell on a plastic label and place them in the trays where you'll want the seeds to go before planting.

Doing this first helps map out your placement, determine the amount of room you have AND helps avoid the mystery plant syndrome.

5. Use a chopstick or other small tool to make a shallow indentation, then sprinkle in 2 or 3 seeds.

You'll eventually thin to 1, but this allows for different rates of germination. Flat, bigger seeds are easy to add to the indentations with your fingers, but for those tiny seeds like onion and broccoli, a small spoon makes it easy to add only a couple.

PRO TIP: plant more than 2-3 seeds if using older seed packets because the germination rate goes down as it ages. Yes, it means there may be more thinning involved which seems wasteful, but believe me, it's no fun to do all this and have only two seeds germinate in a 6-cell and then have to do it all again, only this time much later!

6. Gently cover the seed.

Most of the seeds we start inside are not big ones that need to be deep in the soil, so just barely cover the seed.

You can use a bit more of the dry mix or push some of the moist soil back over the seed.

PRO TIP: Wait until you've added all the seeds to the tray before covering them, just to make sure you've filled all the cells.

7. Plant all cells and water with a gentle WARM spray.

The warmth will give the seeds a little head start, but the real key is to gently water.

You can use a sink faucet spray on low or fill a watering can to water with. Be careful not to flood the cells too much as that will displace the seeds.

8. Place a cover over the tray.

You don't technically have to use a cover, but it does help retain moisture until the seeds sprout. If you don't have an official cover, use some plastic.

You only want the seedlings covered until they sprout so you will need to remove the cover as soon as you see sprouts, even if there are not some in every the cell.

The extra moisture that was great for germination can cause fungus problems on the newly germinated seedlings.

9. Set the tray under your grow light.

BUT don't turn them on yet - the seeds don't need light at this point (while there are a few seeds that need light to germinate, it's mostly flowers that do - check the seed package).

10. Turn on the lights when there are sprouts.

Adjust the light fixture as close to the tops of the sprouts as possible. Like right above the tallest leaves.

This close light is key to stocky, healthy seedlings.

Then as the plants grow, move the light fixture up (this is why the light needs to be on chains or ropes).

11. Keep moist by watering from the bottom.

Always add water to the plastic tray (another reason I like using the cells) - lift a pot/cell and fill tray with water to keep the cells all evenly moist.

Watering from the bottom encourages deep roots, and eliminates any chance of harming the tender seedlings with a spray of water.

It's also a good way to ensure the seedlings will have enough water if you're not able to water for a few days. They will take up what they need from the bottom reservoir.

12. What about fertilizer?

If the seed mix you used has some included, you won't need to add any for most plants grown for 4 to 6 weeks indoors.

For longer growing plants like tomatoes and peppers, I add a no-odor diluted fish emulsion to the water at the halfway mark. You'd do the same thing at about the 3 week mark if using a soil mix that didn't have fertilizer added.

Where to Grow Your Plants Indoors

Windows or Lights?

The most basic source of light is windows, of course, but it's usually not strong enough to produce strong, stocky seedlings.

The seedlings will strain towards the light, growing tall and leggy, especially if you're growing a large tray like I show.

That's why your plants will do best with a light source that can be placed directly over the pots like the options listed in the supplies section.

The light can be attached to a shelf or under a cabinet or you can build a simple stand to hold the light.

You just need to have the ability to raise and lower the light source as the plants grow.

Options for Where to Start Your Indoor Seedlings

Basically, anywhere you can make a bit of space for a few months!

1. In the Kitchen

For many years, I started seeds in a corner of my kitchen, shown above.

The shop light was hidden most of the year and when I needed the light, I moved the storage jars, set my trays in place and lowered the light for the few months I'd need.

2. Use a Structure

In a previous house we built a simple structure out of 2x4s that we hung the lights from and kept in an office. You can also use an existing shelf you can attach lights to, or buy a metal greenhouse shelf system.

Wherever you keep the light though, it should still be in the house, or at least someplace where it doesn't get too cold.

3. Under a Dedicated Shelf

We planned for a dedicated seed starting area in our previous our mudroom, seen above. It was wonderful not having to move items out of the way when to grow seeds.

Other ideas: an insulated garage, a table in a guest room, or even a corner of the dining room.

More in the Seed Starting Series:

• Vegetable Garden 101: Caring For Seedlings at Week 1
• Vegetable Garden 101: Caring for Seedlings at Week 6
• Vegetable Garden 101: How to Plant Seedlings in the garden

This article has been updated - it was originally published in 2009, updated in 2016 and again in 2022.

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