Garden of Eatin' / How-To / Seeds & Seedlings

The Beginner’s No-Fail Guide to Starting Seeds Indoors

The no-brainer guide to starting seeds indoors

Exactly as the title says — this is an easy, no-fail guide to indoor seed starting.

You don’t need to read any gardening books first. You don’t need any fancy equipment. You just need your seeds (these are the best garden seed catalogs that I order from every year) and a few basic supplies to get started.

Whether you have a dedicated vegetable bed in your backyard, or a cluster of containers on your patio, it all starts out the same way. You have to plant your seeds, and germinating seeds inside your home (where you have the most control) is the best way to do so.

Starting seeds indoors is ideal if you want to get a head start on the season, or if the weather is still too hot or too cold to put anything in the ground.

Related: Know When to Grow: A Planting Calendar for Your Garden

This simple step-by-step tutorial will take you from seed to seedling with a minimum of fuss. Just the stuff you need to know, and none that you don’t. (But if you’re the really-need-to-know type, I’ve added footnotes at the end to explain why you’re doing what you’re doing.)

This post contains links to products from one or more of our advertisers. We may earn a commission if you buy something through one of our links. How this works.
Legume seedling started indoors

How to start seeds indoors: a step-by-step guide

Step 1: Gather your seed starting supplies.

  • Seeds
  • Seed starting pots or cell trays
  • Plant markers
  • Seed starting mix (homemade or store-bought)
  • Seed tray with humidity dome (often called a 1020 plant tray or propagation tray, or use any DIY drainage tray with plastic wrap)
  • Spray bottle or squirt bottle filled with water

If you’ve already made your recycled newspaper pots, you’re all set. If you’ll be using other seed starting pots or cell trays, make sure they’re clean.1

You can also repurpose household items into seed starting containers, like egg cartons, Dixie cups, and yogurt cups. Just wash them out and poke a few drainage holes in the bottom with a nail or an awl.

Step 2: Fill your pots or trays with seed starting mix.

Dump your seed starting mix into a large tub or bucket, pour in a generous amount of water, and stir it up with your hands or a trowel.

As the seed starting mix starts to absorb the moisture, add more water as needed. (This will take several minutes, as peat-based seed starting mixes are slow to absorb.) You want the mix to be uniformly damp, like wet sand.

Fill your seedling pots with this pre-moistened seed starting mix.2

Step 3: Sow your seeds.

Place two to four seeds on the surface of the seed starting mix, and gently press the seeds down so they’re nestled in nicely.

If your seeds are very small, like basil or mustard, you can leave them uncovered.3

If your seeds are larger (like beans or peas) or they require darkness to germinate (check the instructions on the seed packets), cover them with a layer of vermiculite or seed starting mix equal to their height, usually 1/4 inch to 1/2 inch.

Step 4: Label your newly planted seeds.

Label each pot. Trust me, you will never remember what you planted where, as most seedlings look the same at birth.

At this early stage, cheap plastic plant markers work very well and stay out of the way, so save your big and beautiful metal plant markers for the garden.

Step 5: Keep your seeds moist and warm.

Mist your seeds with water.4

Assemble your pots in a seed tray (or reuse a disposable aluminum roasting pan, a baking pan, even that plastic clamshell that your salad greens came in) and cover with a humidity dome (or just plain old plastic wrap).5

If your dome has vents, keep them open to help with air circulation during the sprouting period.

Now, you need to add heat. Since sunlight is not essential at this point, your seed trays can be placed wherever it’s warmest in your house, such as an attic, bathroom, laundry room, or kitchen.6

Seedlings gaining warmth from their mini greenhouse by the window

If your seedling pots stay covered in a warm nook, the low humidity will keep your seeds happy until they sprout. High humidity will make them sad. Only spritz the seeds with more water if the mix feels dry to the touch.7

Within a couple of days to a couple of weeks, the seeds will germinate. As your seedlings start to emerge, some of them will look like they’re wearing little seed hats.

Germination (the process of a seed sprouting) is highly variable, so don’t stress if it feels like it’s taking forever to happen. In most cases, seeds will germinate within three weeks (after that, try starting a new round of seeds).

Newly sprouted seed
One-day-old seedling
Bean seedling

Step 6: Give your new seedlings light.

At this stage, the newly germinated seedlings need light. Remove the humidity dome or plastic wrap, and move the seedlings to the sunniest spot in your house (preferably a south-facing window).

Continue to keep the mix moist, but not overly wet. Seedlings should be watered once a day or every other day, depending on how much sun and heat they get.

Remember that seedling roots are fairly close to the surface and they’re growing in a small amount of media, so they don’t need a deep soak the way larger plants do.

I like using spray bottles or squirt bottles, as the gentle streams of water won’t displace seeds or damage seedlings.

Give your new seedlings plenty of light and warmth for fast growth
Carrot seedlings
Keep seedlings moist

Step 7: Moving day! Transplant the strongest seedlings when they’re ready.

After your seedlings develop their first “true set” of leaves, they are ready to be transplanted.8

Wait for seedlings to develop their first true leaves before transplanting

If more than one seed sprouted, choose the strongest one and pinch or snip off the others. You can even keep all of them, but be careful separating the roots if the seedlings are close together.

Transplant the seedling into a larger container filled with potting mix. Hold it by the cotyledons (the first leaves that appear) and try not to manhandle the tiny roots.

Transplant seedlings into larger pots once their true leaves have emerged

At this stage, you can lightly drench the potting mix using a diluted solution of compost tea or all-purpose fertilizer. Keep it simple, keep it organic, and don’t obsess too much over the nutrients.9

Give the seedling plenty of sunlight each day (at least 12 to 16 hours is optimal for most vegetable seedlings) to avoid the “leggy” look. (Learn how to fix leggy seedlings if this is happening to you.)10

Step 8: Harden off those seedlings.

To get your seedling prepped for a good life outside, you can start to harden off the seedling11 by moving it outside under diffused light for a few hours and bringing it back inside each night.

Over the next week, move it from diffused sun to partial sun to full sun, and for longer periods of time, until it’s finally kept outside all night.

Step 9: Transplant your seedlings outdoors.

After the hardening off period, you can transplant your seedling to its final destination, whether straight into your garden or into a larger container.

And then, in a couple of months, you can enjoy the fruits (and veggies) of your loving labor!

More Ways to Start Seeds Indoors

There's more than one way to start your seeds and make sure they sprout!

Footnotes

1 This seems obvious, but laziness gets the best of us. Clean pots are key and help keep damping off at bay (an untreatable fungal disease that causes seedlings to suddenly keel over and die at the soil line).

Discard or thoroughly wash any pots that previously housed diseased plants. Avoid using leftover soil from the nursery container you brought home, as it might harbor weed seeds and bad bacteria.

If you have a healthy garden, you can skip washing your pots and simply dump out the dirt from your pots before using again.

I’ve put countless seed trays and humidity domes to the test over the years, and found these trays and domes to be the thickest and strongest on the market — they don’t bend, flex, or crack as easily as other brands, and can be reused for many seasons. back

2 It’s easier to start with pre-moistened mix, as peat-based mixes are harder to wet down uniformly if they dry out in pots. Although peat has a very high water-holding capacity once it’s wet, it actually repels water when it’s dry. Go figure.

If you’re not using homemade seed starting mix, this is a reputable brand that I like. You do not need anything fancy; seeds just need a basic mix of perlite, vermiculite, and peat moss (or coco coir) to germinate and grow into healthy seedlings. back

3 For certain varieties of plants, light will often speed up germination (the process of a plant sprouting from a seed). back

4 The moisture will help the seeds shed their protective coating and eventually sprout. back

5 This creates a greenhouse effect to keep your seeds moist and warm, the key to germination. Most annual vegetables germinate best in temperatures of 75°F to 90°F. A few, such as radish, will germinate at lower temperatures.

Seeds will sometimes sprout in less than ideal temperatures, but the germination period will be longer. back

6 I like to put my seed trays next to my heating vent on the floor. Some gardening guides suggest placing your tray on top of a refrigerator, but most appliances these days are energy-efficient and do not give off much heat. back

7 Too much water will make the seeds rot. If your makeshift greenhouse is looking a bit too wet inside, remove the cover or plastic wrap for a few hours during the warmest part of the day to allow air circulation. Mold is no good for seeds, either. back

8 The true leaves are actually the second set of leaves that appear; the first leaves that initially unfurl are not leaves at all, but cotyledons. These leaf-life structures are part of the embryo of the seed, and supply food to the seedling until its true leaves begin the process of photosynthesis. back

9 I like to use home-brewed compost tea or liquid sea kelp. No fertilizer is fine, too, especially if you start with good soil. I have grown healthy vegetables with no fertilizer through a whole season, and could barely keep up with the harvests. back

10 It sounds sexy, but it makes your seedling tall and weak as it channels its energy into straining for sunlight. I also like to gently run my hands across the top of my seedling to simulate a breeze; this slows down initial growth and strengthens the stem. A few brushes a day is all it needs. back

11 Hardening off is the process in which you gradually acclimate the seedling to its future environment outdoors… getting it acquainted with the breeze, the birds, and the bees. back

Where to buy indoor seed starting supplies

The Beginner's No-Fail Guide to Starting Seeds Indoors 5
Bootstrap Farmer Multi-Color Extra Strength Seedling Trays | Bootstrap Farmer Extra Strength 1020 Propagation Trays | Bootstrap Farmer 32-Cell Seedling Starter Tray | Bootstrap Farmer 32-Cell Seedling Starter Tray with Inserts | Bootstrap Farmer Humidity Dome | Koram Seed Starter Trays with Lid and Base | Behrens Galvanized Steel Pail | Black Gold Seedling Mix | Hoffman Canadian Sphagnum Peat Moss | Hoffman Horticultural Vermiculite | Hoffman Horticultural Perlite | Kinglake 4-Inch Plastic Plant Marker | Staedtler Lumocolor Permanent Garden Marker

The Beginner’s No-Fail Guide to Starting Seeds Indoors

Use cheap paper pots from the dollar store for starting seeds

If you're new to seed starting, this foolproof beginner's guide to starting seeds indoors will take you step by step from seed to harvest, quickly and easily.

Materials

  • Seeds
  • Seed starting pots or cell trays
  • Plant markers
  • Seed starting mix (homemade or store-bought)
  • Seed tray with humidity dome (often called a 1020 plant tray or propagation tray, or use any DIY drainage tray with plastic wrap)
  • Spray bottle or squirt bottle filled with water

Tools

  • Large bucket or tub
  • Trowel

Instructions

  1. Gather your seed starting supplies. Instead of seed starting pots, you can also use recycled newspaper pots, or repurpose household items into seed starting containers, like egg cartons, Dixie cups, and yogurt cups. Just wash them out and poke a few drainage holes in the bottom with a nail or an awl.
  2. Fill your pots or trays with seed starting mix. Dump your seed starting mix into a large tub or bucket, pour in a generous amount of water, and stir it up with your hands or a trowel.

    As the seed starting mix starts to absorb the moisture, add more water as needed. (This will take several minutes, as peat-based seed starting mixes are slow to absorb.) You want the mix to be uniformly damp, like wet sand.

    Fill your seedling pots with this pre-moistened seed starting mix.
  3. Sow your seeds. Place two to four seeds on the surface of the seed starting mix, and gently press the seeds down so they’re nestled in nicely.

    If your seeds are very small, like basil or mustard, you can leave them uncovered.

    If your seeds are larger (like beans or peas) or they require darkness to germinate (check the instructions on the seed packets), cover them with a layer of vermiculite or seed starting mix equal to their height, usually 1/4 inch to 1/2 inch.
  4. Label your newly planted seeds. Label each pot. At this early stage, cheap plastic plant markers work very well and stay out of the way, so save your big and beautiful metal plant markers for the garden.
  5. Keep your seeds moist and warm. Mist your seeds with water.

    Assemble your pots in a seed tray (or reuse a disposable aluminum roasting pan, a baking pan, even that plastic clamshell that your salad greens came in) and cover with a humidity dome (or just plain old plastic wrap). If your dome has vents, keep them open to help with air circulation during the sprouting period.

    Now, you need to add heat. Since sunlight is not essential at this point, your seed trays can be placed wherever it’s warmest in your house, such as an attic, bathroom, laundry room, or kitchen.

    If your seedling pots stay covered in a warm nook, the low humidity will keep your seeds happy until they sprout. High humidity will make them sad. Only spritz the seeds with more water if the mix feels dry to the touch.

    Within a couple of days to a couple of weeks, the seeds will germinate. Germination (the process of a seed sprouting) is highly variable, so don’t stress if it feels like it’s taking forever to happen. In most cases, seeds will germinate within three weeks (after that, try starting a new round of seeds).
  6. Give your new seedlings light. At this stage, the newly germinated seedlings need light. Remove the humidity dome or plastic wrap, and move the seedlings to the sunniest
    spot in your house (preferably a south-facing window).

    Continue to keep the mix moist, but not overly wet. Seedlings should be watered once a day or every other day, depending on how much sun and heat they get. Remember that seedling roots are fairly close to the surface and they’re growing in a small amount of media, so they don’t need a deep soak the way larger plants do.
  7. Moving day! Transplant the strongest seedlings when they're ready. After your seedlings develop their first “true set” of leaves, they are ready to be transplanted.

    If more than one seed sprouted, choose the strongest one and pinch or snip off the others. You can even keep all of them, but be careful separating the roots if the seedlings are close together.

    Transplant the seedling into a larger container filled with potting mix. Hold it by the cotyledons (the first leaves that appear) and try not to manhandle the tiny roots.

    At this stage, you can lightly drench the potting mix using a diluted solution of compost tea or all-purpose fertilizer.

    Give the seedling plenty of sunlight each day (at least 12 to 16 hours is optimal for most vegetable seedlings) to avoid the “leggy” look. (Learn how to fix leggy seedlings if this is happening to you.)
  8. Harden off those seedlings. To get your seedling prepped for a good life outside, you can start to harden off the seedling by moving it outside under diffused light for a few hours and bringing it back inside each night.

    Over the next week, move it from diffused sun to partial sun to full sun, and for longer periods of time, until it’s finally kept outside all night.
  9. Transplant your seedlings outdoors. After the hardening off period, you can transplant your seedling to its final destination, whether straight into your garden or into a larger
    container.

Did you make this project?

Please leave a comment on the blog or share a photo on Instagram

What to know after your seeds germinate

This post updated from an article that originally appeared on March 19, 2011.

Linda Ly About Author

I'm a plant lover, passionate road-tripper, and cookbook author whose expert advice and bestselling books have been featured in TIME, Outside, HGTV, and Food & Wine. The No-Waste Vegetable Cookbook is my latest book. Garden Betty is where I write about modern homesteading, farm-to-table cooking, and outdoor adventuring — all that encompass a life well-lived outdoors. After all, the secret to a good life is... Read more »

67 Comments

  • Avatar
    Yolonda Fortunato
    July 21, 2017 at 12:47 am

    Hello, I am a beginner indoor herb grower. Unknowingly, I placed my basil, thyme, parsley pots in the window sill for two days before they sprouted. After reading this blog, I immediately removed them to the closet covered with clear plastic wrap. Do you think those two days in the window sill with sun will prevent them from germinating properly?

    Reply
    • Avatar
      Yolonda Fortunato
      July 21, 2017 at 2:52 pm

      Update: checked on my pots this morning, and four basil seeds have sprouted, and three thyme seeds sprouted, and the parsley seeds are looking healthy. ❤

      Reply
      • Avatar
        Linda from Garden Betty
        August 6, 2017 at 8:17 am

        So happy it worked out for you!

        Reply
  • Avatar
    Tosha Mitchell
    April 12, 2017 at 2:55 am

    I planted my seeds today and instead of lightly covering my seeds I pressed them down in the soil. Will this affect the growth?

    Reply
  • Avatar
    Tiffany Birmingham
    April 4, 2017 at 6:07 pm

    I went big and .. planted everything i could get my hands on last wednesday and thursday. of course some plants took off as others are taking their time. i cracked open 2 or 3 lids this morning and they sit in a dark warm garage right now. I am going to take a leap here and say I might be able to take a bulbed aquarium light and place over my seeds ? They are all on a metal rack in my garage so maybe place the light one row up and it would cover all 5 trays of seeds or should i just take them all to the back door for light all day ? my beans and peas as well as some others are about 2 to 3 inches high.

    Reply
  • Avatar
    VirgoChef
    March 20, 2017 at 3:23 pm

    Hi, I’m a first time gardener and I’m overwhelmed! There is so much information out here it’s hard to know what to do. This article was great! Thank you! I do have a few questions though. I started some seeds in a container with a dome and the seeds sprouted very quickly and were super leggy. Someone told me to put them in a shady spot inside as I do not have a grow light. Most of them died and all of them flopped over and the heads broke off or bent. I bought a new dome and replanted last week, the seeds are already sprouting and your article said to remove the dome and place them in a sunny spot in the house, is this correct? This will keep them from getting leggy? What about the couple that have not sprouted yet? Also, I planted some Dragon’s Tongue beans and okra in yogurt cups and they are growing very quickly. Are they ok in those cups until I plant them outside or should I put them in a larger pot? I’m planting everything in containers on my patio as I live in an apartment, is it ok to direct sow the flowers I will be planting? Morning Glories, Poppies, maybe Sweet Peas too? Will my cat be safe around these things? Thank you!

    Reply
    • Avatar
      Linda from Garden Betty
      March 22, 2017 at 4:52 am

      Unless you have seeds that require darkness to germinate, you can put your seed starting tray in a sunny window. Once they sprout, seedlings need sufficient light for growth. You can learn more about leggy seedlings and how to correct them here: http://www.gardenbetty.com/2017/02/leggy-seedlings-what-causes-them-and-how-to-correct-them/

      Once your seedlings reach 3x the height of their seed starting container, they should be transplanted — or even sooner, if they’re overcrowded and you haven’t thinned them. Leaving them in small cups can cause them to get leggy or rootbound.

      All your flowers can be direct sown (as can the vegetables you mentioned). I’m not really familiar with what type of vegetation is toxic to cats, but as long as your cat doesn’t have a tendency to eat your plants, it’ll be fine.

      Reply
  • Avatar
    Constance
    May 10, 2016 at 2:28 pm

    I was wondering if you could tell me if the room temperature matters to the success of seedlings? My seeds have sprouted, and I have them under floresant grow lights, but the room they are in is quite cool because it’s in the basement. When the timer turns the lights off, do the seedlings need to be kept warm?

    Reply
    • Linda Ly of Garden Betty
      Linda Ly of Garden Betty
      October 17, 2016 at 10:21 pm

      It’s not so much the temperature of the air that affects growth, but the temperature of the soil. Most seedlings do their best in soil that stays on the warmer side, so if yours feels very cold, I recommend getting a heating mat or moving the seedlings to a warmer room.

      Reply
  • Avatar
    Miriam Caccese
    March 27, 2016 at 6:26 am

    I have a question. We bought one of those plastic, shelf like greenhouses with green plastic covering. My seedlings are all doing great inside the house under a grow light and all have sprouted. I’m going to transplant into larger pots and don’t have enough room to keep them under the grow light at that time. Can I move them into the greenhouse with no more grow light? I’m in zone 7 and our last frost date is 3.5 weeks away. Also should I start taking them out of the green house during the day for a few hours to start hardening off since plant date is almost here and then put them back in? Nighttime: inside the house or inside the greenhouse? Can’t find answers to this anywhere. Please help 🙂

    Reply
    • Avatar
      Sandi Whisper-Creations
      April 18, 2016 at 7:26 am

      I would love to know the answer to this also. I’m in zone 6 and running out of space too!!

      Reply
    • Linda Ly of Garden Betty
      Linda Ly of Garden Betty
      April 27, 2016 at 9:05 pm

      Assuming your greenhouse gets enough light, you can certainly keep your seedlings in there until they move outside. As for whether you should start to harden them off now, that depends on your forecasted weather the next couple weeks. If no frost is imminent, you can begin to acclimate your seedlings. I’ve written more about that process here: http://www.gardenbetty.com/2014/03/how-to-harden-off-your-seedlings/

      Reply
  • Avatar
    Jessica Seigner
    March 22, 2016 at 7:16 pm

    I started my seeds inside on my window sill,I usually start them outside where they will live but its been too windy, now the little fellers have sprouted I realized there is no sunny spot inside I live in hawaii so frost or cold arent an issue how do I safley move them outside to the sun before the true leaves come in? a grow light is not an option for me and the little maters are getting quite leggy.

    Reply
  • Avatar
    Mj
    March 22, 2016 at 1:16 pm

    Hello! I’m new to gardening and seeds but I’ve been looking for some information and I just can’t seem to find it. Any help would be greatly appreciated. I started seeds using toilet paper rolls with the ends folded up but I think I may have just barely over watered them because there is light white mold growing on the outside, bottom part of the containers but none on the top of the soil. I tried using cinnamon & giving them plenty of air to stops this but it keeps coming back. A lot of the seeds have already started sprouting, so my question is, would it be okay to move the seeds into different containers? Or since there is mold present do I have to scrap these little guys and start fresh? They’re so cute & healthy looking I would hate to lose them. Again thank you for any help. Newbie here. Also great article, can’t wait to try that compost tea!

    Reply
    • Linda Ly of Garden Betty
      Linda Ly of Garden Betty
      April 27, 2016 at 12:33 am

      Hard to say if the mold will have any effect on the seedlings, since you say it’s only growing on the outside of the containers. Cut back on the watering a bit and try running a fan to increase circulation. You can let the seedlings continue to grow until they form their true leaves, and then transplant them immediately. I’d also recommend a dose of compost tea once they’re transplanted.

      Reply
  • Avatar
    SongeSinger
    March 4, 2016 at 8:44 pm

    aren’t the seeding trays you buy with the plastic domes meant to hold water which wicks up through the individual sections to keep seeds moist? or should I only water lightly from top? additionally I tried for the heck of it putting moist seed start mix and seed in peat pots and set the pots in a tray with water in it. do you have an idea how long peat pots will last before they fall apart in that situation? does this make sense? lol I will save this page in case you answer. thanks

    Reply
    • Linda Ly of Garden Betty
      Linda Ly of Garden Betty
      March 7, 2016 at 2:20 pm

      You can use the plastic trays either way. With seeds, I water from the top since only the surface needs to be kept moist until roots develop. I generally only start watering from the bottom when I’ve transplanted the seedlings into 3-inch pots.

      I’m not sure I’m understanding what you’re doing with the peat pots… are you keeping them in water permanently? I don’t recommend it, as peat pots are designed to decompose with moisture (which is why they’re great for transplanting directly into a garden, pot and all). They’ll survive regular watering until your seedlings are sturdy enough to transplant, but I personally wouldn’t bottom-water them unless you’re starting a very fast-growing crop (like beans or corn).

      Reply
1 2

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.