Indoor Seed Starting

The first seeds I ever started indoors grew inside one of those plastic salad boxes from the grocery store that I had repurposed and poked some holes into the bottom. I then tried egg cartons and even literal eggshells.

Since then, my supplies have gotten a little upgrade, and I've learned what you really need to successfully start healthy seeds indoors. If you don't have all these supplies, don't worry. It's better to just get started than to wait till everything's perfect.

I just got started with my sad little plastic container years ago, and I want you to just get started too, so I'm including budget-friendly options along with my recommendations mentioned below.

Just get started. Once you get your hands a little dirty and watch your first seed babies grow, you'll be hooked on starting your own seeds at home and can add to your toolkit as you go along. Our number one priority with starting seeds indoors is to imitate nature indoors (sunlight, wind, water, etc.), and you can do that with all different kinds of supplies.

Overview of the supplies and tools you'll need to begin starting your seeds indoors

Supplies:

• Seed starting mix
• Container with a drainage hole
• Container that holds water
• Dome or system that will create humidity
• Grow light
• Water
• Bowl
• Plant tags or painter's tape to label
• Permanent marker
• Gloves
• Dibber or something to make a hole in the soil
• Seeds

Seed starting mix vs potting soil

It's important to use a special seed starting mix rather than regular potting soil when starting seeds indoors. Seed starting mix is a bit finer and lighter than regular potting soil to give baby roots room to push out of the seed and grow. Regular potting soil (pictured below) is heavier and denser to support roots, provide nutrients, and hold soil in place.

You can purchase mixes that are ready to go or you can make your own.

The best seed starting soil mixes

The easiest way to get started is to buy an organic seed starting mix from the store. I generally try to stay away from peat moss and other nonrenewable resources due to their lack of sustainability, but peat can be found in almost all seed starting mixes. A good alternative option to look for are mixes made of coco coir.

• This seed starting mix from Espoma does contain peat moss, but I like that it has mycorrhizae to promote good root growth (price: $25.50 for 8-qt. bag on Amazon).
• This organic mix from SunGro helps keep seeds moist for better germination rates (price: $27.86 for 1.5 cu. ft. on Amazon).
• This Purple Cow Organics mix is compost-based (price: $25.99 for a 12-qt. bag on Amazon).
• This blend from Coast of Maine contains mycorrhizae, worm castings, kelp, and compost ($18.79 for 8-qt. bag on Amazon).
• This Whitney Farms mix is a bit cheaper than other organic options but does not have moisture control (price: $15.96 for 8-qt. bag on Amazon).

In lieu of shopping on Amazon, you could stop by your local nursery or garden center to find an organic seed starting mix recommended by growers near you.

Seed starting mix on a budget

Rather than skimp and buy a non-organic mix (which might contain chemicals or synthetic agents), make your own. I give you my exact specifications for what I call the 103, a mix of compost, topsoil, and coarse sand, in my book, Kitchen Garden Revival, and in our course, Kitchen Garden Academy.

For seed starting, you'll avoid using as much sand as you would when making soil for your garden. The ideal seed starting mix consistency will hold together better than the soil you'd use in your garden when wet. That's why you'll see common seed starting mix ingredients including things like vermiculite, perlite, and coco coir.

The best seed starting trays and containers

The most important thing here is that whatever container you use has drainage. Don't even bother starting seeds in anything that doesn't have a hole in the bottom, as seeds do not like to sit in water.

You'll start one seed per cell, so keep in mind how many seeds you want to start each season for your garden when purchasing a product.

Draining containers

These containers should have holes in the bottom of each cell and should be placed inside a larger container to hold water.

Biodegradable seed starting trays

You can purchase these trays, which are made of wood fiber, for fairly cheap, like these 2"-trays from Gardener's Supply, which cost $5.95 for 36 cells.

The benefit is that you can just put these plants right in the soil and avoid transplant shock (in other words, damaging a plant's roots when moving it to its new home in the garden), but I've found that these degrade too quickly. The sides will warp after exposure to water, so I prefer using plastic.

plastic seed starting trays

I usually try to avoid using plastic, much less going out of my way to buy plastic, but I use my plastic trays again and again and again. Between batches of seeds, I simply give my trays a good cleaning. I love that my trays have lots of cells and, again, are reusable season after season.

These trays are sold ten per pack for $21.96 on Amazon, and each tray has 72 cells, each with a drainage hole.

root trainers

These come flat but then fold together like a clam shell to give your plants more space to develop roots and avoid roots spiraling around each other.

The Deep Rootrainer from Gardener's Supply has 32 cells and comes with a holding frame, all reusable, for $24.95.

Non-draining containers

You'll need something that holds water to go underneath your draining container.

These non-draining trays from Amazon come in a set of 10 and cost $24.50.

Seed starting kits

You can buy non-draining trays together with draining trays as kits, like this five-pack kit for $27.99 on Amazon.

If you don't like the idea of using plastic, check out this six pack of galvanized seed starting trays, each with nine metal holes, for $34.99 on Amazon. You can watch me fill them in the video below.

Seed starting domes

Most seed starting kits will usually come with a dome. You'll only use the dome at the very outset of starting your seeds to help keep moisture inside until the seeds germinate. Once your seeds germinate, you'll want to remove the dome (and also pull the seedlings off any warming mats, should you decide to use them).

Seed starting containers on a budget

Use plastic containers or thoroughly washed egg cartons with holes added to the bottom of each cell. Place inside a larger plastic container. If you don't have a plastic dome, you can use wet burlap or a wet kitchen cloth to drape over your seeds.

The best seed starting LED lights

An artificial source of light is critical for growing healthy seeds indoors. Ideally, your light source can be raised and lowered because you'll want your light source very close to the seeds as they're just starting to germinate. As the seeds grow, you'll want to be able to raise the light source to give the leaves more room.

Also, look for a full spectrum light.

My new favorite type of LED lights are these clip-on lights from Amazon for $19.89, or similar versions (pictured below). I love that the clips can easily attach to the side of a shelf or tabletop. The lights are on a coil, which means you can maneuver them over plants and control their angle and height. You can even extend two lights over one large tray or split two heads between two separate trays.

There are also floor lamp versions for $31.99 on Amazon.

Look for lights with a timer or remote to simplify your life.

Seed starting lights on a budget

If you're not ready to invest in artificial lights, then you'll use free solar light, and by that, I mean the sun.

I've grown seeds in a window sill and even using ambient light in my kitchen before. However, I've found that seedlings grown without artificial light tend to be leggy or lean over too much because they're looking for sunlight. It's rare for baby plants to get enough light to be fully healthy and robust from just sunlight indoors. 

Other recommended supplies for seed starting

• water
• a large bowl to combine your seed starting mix and water before planting out your seeds
• sticks to label (you can do plant tags like these or these, or use a marker to write on popsicle sticks or tape to stick on the outside of your trays)
• a marker to write the type of seed, the name of the seed company, and the date you planted it
• gardening gloves if you don't like getting your hands dirty (I highly recommend this pair)
• a dibber to easily make a hole in the seed starter mix (budget options: your finger or a chopstick)

And last but definitely not least, you're going to need some seeds. In fact, you're going to need a lot of seeds! Look for organically sourced, non-GMO seeds, and when possible, shop local. I caution you against ordering any seeds, however, until you have at least some basic equipment to get them started.

Here are links to some of my favorite seed companies:

• Baker Creek
• High Mowing Organic Seeds
• Botanical Interests
• Territorial Seed Company
• Southern Exposure
• Seed Savers Exchange

To learn more about what to prioritize when shopping for seeds, watch our Seed Starting course in Gardenary 365. This article comes from just one of the 11 lessons waiting inside your 365 membership.

It might seem like there's a lot to buy right now to start your own seeds indoors, but just remember that you don't have to have everything to get started. Next time you go to your local nursery, you can buy some more seed starting supplies and skip right past all of those super expensive starter plants, a self-satisfied smile on your face. Because now you know how to start your own from seed!

Remember, don’t feel like you have to start big or it’s not worth it. One tray could help you start loads of big plants that will fill your garden beds in the months to come. Though these seeds are tiny now, they’ll soon grow into huge plants.

So, don’t wait till you can start big to start... start small and grow from there.

Happy seed starting!

Some of the links in this article are Amazon affiliate links, which means I receive a small commission at no extra cost to you if you click on the link and purchase the item. The links to stores outside of Amazon are not affiliated—they're just products I really like. All opinions remain my own.