The No-Brainer Guide to Starting Seeds Indoors

Seedlings started indoors in newspaper pots

Exactly as the title says — this is an easy and foolproof guide to starting seeds indoors.

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. Growing seedlings 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.

This simple step-by-step 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.)

We’ll start with the basics of what you should gather:

If you’ve already made your recycled newspaper pots, you’re all set. If you’ll be using other seedling pots, make sure they’re clean.1 You can also repurpose household items like egg cartons, Dixie cups, and yogurt cups — just wash them out and poke a few drainage holes in the bottom.

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

Place two or three seeds on the surface, and gently press the seeds down so they’re nestled into the mix. If your seeds are very small, like basil or peppers, you can leave them uncovered.3 If your seeds are larger, like beans or peas, or they require darkness to germinate, cover them with a layer of vermiculite or seed starting mix equal to their height, usually 1/4 inch to 1/2 inch.

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

Label all your seedlings

Mist your seeds with water from a spray bottle.4

Assemble your pots in a seed tray (or reuse a disposable aluminum roasting pan, a baking pan, even that plastic container that your cookies came in) and cover with a clear 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.

Cover seedlings with a dome to simulate a greenhouse effect

Keep your plastic dome vented for air circulation

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

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 or a couple of weeks, the seedlings will start to emerge. They’ll look like they’re wearing little seed hats.

Seedlings emerging

Now, they need light. Remove the clear dome or plastic wrap, and move the seedlings to a sunny spot in your house, such as a south-facing window. Continue to keep the mix moist, but not waterlogged.

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

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 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 to avoid the “leggy” look.10

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 full sun, and for longer periods of time, until it’s finally kept outside all night.

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!

Footnotes For the Curious
1 This seems obvious, but laziness gets the best of us. Clean pots are key. That dirt from last season, or the leftover soil in the nursery container you brought home, may house weed seeds and bacteria. Cleanliness keeps damping off at bay (an unexplainable fungal disease that causes seedlings to suddenly keel over and die at the soil line). The simplest prevention is to just swish your pots in hot water and a little soap. 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. back

3 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 75-90°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 central wall heater. 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 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 by which you gradually acclimate the seedling to its future environment outdoors… getting it acquainted with the breeze, the birds and the bees. back

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March 19 2011      44 comments     Linda Ly
Jardín   Semillas   Verduras

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  • Jaycee Bridges

    This is such a great site! Absolutely loving it and I’ve already started pinning your blogs.

    Quick question regarding light. Historically I’ve started my seeds next to a large wall of windows, unfortunately they’re north facing. The last few years my seedlings have been pretty leggy. They did fine in the garden, and eventually produced more than I could handle, but I think they got really late starts on fruit production. So, this year I added a grow light to the mix. I typically only use the grow light in the evenings for a few hours. Basically, I’m just curious what you do for the light component at this stage.
    Also, when do you first fertilize?

    • http://www.gardenbetty.com/ Linda Ly

      Thank you!

      I have my seedlings in a south-facing window, so I have enough natural light available until they go in the garden. At minimum they should get 12 hours of light a day, but if you’re using a grow light, 14-16 hours would be even better. I don’t fertilize until they’re transplanted outside, but if I repot them into 4-inch pots, I add compost to the potting soil and that will feed them for a few weeks.

  • Blair

    I love your blog! You don’t often find a blog where it’s all about getting dirty. I love it!

    • http://www.gardenbetty.com/ Linda Ly

      Thanks Blair!

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  • Carlos

    Very useful advice, thank you! I also starting from seed indoors for the first time. I’m attempting to grow Coastal Redwood trees which have a low germination rate apparently… I’ve placed the seed trays inside propogation trays and in the hot water cupboard. Fingers crossed!
    Thanks again :-)

    • http://www.gardenbetty.com/ Linda Ly

      I hope you have a big yard to plant them in! ;-)

      • Carlos

        I do luckily! :) I’m actually aiming to grow them into bonsai trees. If I manage to get a few to germinate, one will be going in the yard.

        I’ve read stories about redwood trees… won’t be planting close to the house, that’s for sure.

  • Lauren

    This is going to be my first year attempting to starting seeds indoors, thanks for all the information! I know you said that there are many options for seed trays, but I was wondering what you use? Thanks!

    • http://www.gardenbetty.com/ Linda Ly

      I just use the generic black trays you can find in any nursery (what you see in the pictures).

      • Lauren

        Thank you. I’m going to try Filius Blue peppers!

  • Melina

    What if I fill the newspaper pots with potting soil, make a well in the center and fill it with seed starting mix, and start my seeds in it? That way, I won’t have to transplant my seedlings into bigger pots, and I can just plant the whole lot in the ground when they’re big enough. Is that a bad idea? I’m a brand new gardener, and I don’t know anything about this stuff. I’m just wondering if this will streamline the process and reduce the risk that I’ll kill my seedlings when they grow beyond their little starter pots.

    • http://www.gardenbetty.com/ Linda Ly

      Transplanting just means to either move the seedlings into a larger pot, or move them into the ground (if it’s warm enough by the time they’re ready). If you don’t thin out your seedlings, they’ll outgrow their seed starting pots quickly and you’ll have to transplant them somewhere regardless.

      • Melina

        Thanks, Linda–I guess what I really meant, was this:

        I started a bunch of seeds in egg cartons. For some of them, it was okay, because they didn’t grow that fast, and I’ll be moving them into pots before putting them into the ground. But my peas, for example, grew really fast, and their roots were growing through the egg carton within a few days. They weren’t ready to go into the ground, but they couldn’t stay in the egg carton.

        I ended up breaking some of their roots, trying to detach them from the cardboard egg carton to move them into pots.

        Might I have avoided that problem if I’d started them in a pot to begin with?

        Because I’m so inexperienced, I don’t know which seedlings grow too quickly for the little egg carton wells. So, I thought that if I start them in a pot with potting soil, I can plant them in the ground when they’re ready, and be less likely to traumatize them.

        • http://www.gardenbetty.com/ Linda Ly

          Sure, you can start seeds in any kind of container you have. But if your peas grew that quickly, you should just start them later, or start them directly in the ground when it’s warm enough (which is what I do, since the vines get so long and straggly). I only start seeds indoors for plants that take a long time to grow.

  • Josh McKibben

    I really like the design of and information provided on your site, so thanks for keeping it going! I live in TX and last night I sowed several seeds in peat containers. I’ve added heat pads under each seed tray but here is where it gets tricky. I’m lighting one with compact fluorescent lights and the other with LED’s. Do you think the output of each light will vary much? Meaning…should I adjust one to be on longer than the other? Thanks!

    • http://www.gardenbetty.com/ Linda Ly

      I honestly have no idea, as I don’t use grow lights. But, I do know that you should use full-spectrum fluorescent bulbs if you want to simulate the sun. As neither type of bulb gives off much heat, you’re probably safe setting them at the same distance from your pots. Just don’t forget to adjust them as your seedlings grow.

  • DebH

    I have used plastic salad containers & rotisserie chicken containers for little greenhouses. If just write on the container with a marker as to what I planted. I put labels in the pots when I take the lid off

    • http://www.gardenbetty.com/ Linda Ly

      Great idea!

  • Joie Anne

    I have been looking and looking for this kind of information and I am so happy I stumbled upon yours. OMG!

    I’m doing a campaign for a university project and I’m making a poster regarding this, which means that I will have to actually create this and take a photo of it.

    I have a question..when I was reading info about seed starting indoors, I’m sort of confused if you do water them.. cuz the paper will fall apart once you do.?

    Cheers,

    Joie Anne

    • http://www.gardenbetty.com/ Linda Ly

      Good luck!

    • Penny in Colorado

      Don’t worry – the pots will hold together well enough until it’s time to pot the little seedling up into the next size pots, paper pot and all. After that, the newspaper/toilet paper tube pot will just quietly disintegrate in the new pot of potting mix. Be prepared to pot up several times until it’s the best time to harden off and plant outdoors.

  • Riley Huggins

    Stumbled upon your blog a few days ago and it’s been similar to Christmas every day since! Beyond the gardening (which is how I initially stumbled upon your blog) I love the adventure that you share. I’m from the coast of NC and love to be on the beach and surf but after spending the winter in Aspen, CO I have a new love for snowboarding as well. Your blog encompasses a lot of what I love!

    After finally finding out that my local newspaper used soy-based inks i’ve made my seed starting mix according to your recipe and I’ve planted my seeds for my fall garden – and first garden!

    Your blog is informative, easy to follow, and a great read!
    Here’s to hoping my seeds sprout!
    Cheers from Eastern NC!

    Riley

    • http://www.gardenbetty.com/ Linda Ly

      So happy that you’re here, Riley! It’s thrilling to find out that a lot of people share a similar lifestyle, even though at first glance, gardening and adventuring don’t seem to go together LOL.

      Best of luck with your new garden! I’m sure you/it will do great!

  • Nia

    Thank you for making this process incredibly easy to understand. Lol for days I’ve been *googling* trying to determine the right time to take off the cover and it was never clear. I know this thread is a bit older but I have a question for you. I know in the footnotes you say that you simulate a breeze by brushing your hand over the seedlings. My question is when do you start this process? My seedlings only have their first set of leaves… is this too soon?

    • http://www.gardenbetty.com/ Linda Ly

      I start brushing my hand over the seedlings as soon as they sprout leaves… so, it’s not too soon for you! You’re just trying to mimic the same environment as outside, and seedlings (even new ones) deal with breezes right away.

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  • lifeonbonita.wordpress.com

    Awesome post (and I love your blog)! I hope my seeds come up as pretty as yours! Cheers.

    • http://www.gardenbetty.com/ Linda Ly

      Thank you!

  • Guest

    Love your

  • Duen_tmb

    gardening seems difficult until i read this blog. It made me more confident to grow vegetables..thanks.

  • http://www.berkeycleanwater.com Jeff Wise

    I’m really wanting to get my family started growing our own organic vegetables.  This is great info for me.  I didn’t even know you could start indoors.  I’ll keep browsing your blog because I want to know how much it costs to get started.

    • http://www.gardenbetty.com/ Linda Ly

      The biggest expense of a garden are the soil and amendments. If you don’t have good soil, you’ll have to invest in compost, minerals and fertilizers. The good thing is that the costs diminish over time. Seeds are inexpensive (you can even save your own from plants you’ve grown), and you can make do with very few tools and recycled containers. Good luck!

  • http://www.cicsirvingpark.org/apps/pages/index.jsp?uREC_ID=91793&type=d Ann Kauth

    First of all — I LOVE your site. I’m the garden coordinator for my son’s school (CICS – Irving Park in Chicago: http://www.cicsirvingpark.org/apps/pages/index.jsp?uREC_ID=91793&type=d). Though an avid outdoor gardener, I’ve never done seedlings and am going to attempt this year so the students can see the process from beginning to end. Your step-by-step guide is wonderful. 

    I have a quick question about transplanting — if you use the homemade newspaper cups do you have to transplant seedlings into a larger container?

    • http://www.gardenbetty.com Linda Ly

      Thank you Ann!

      If you start seedlings in newspaper pots, you do not have to transplant again before they go in the garden. Just wait until they grow at least three full sets of leaves, and plant them right in the ground. You only need to transplant into a larger container first if your garden soil is still too wet/cold for your seedlings.

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