A Step-by-Step Guide To Seed Starting Indoors

If you’re a gardening beginner, seed starting may sound like a challenging task. In some ways, buying fully grown plants sounds like a much safer and logical option.

However, when talking to veteran gardeners, they all praise the advantages of growing plants from seed. The truth is that seed starting — or starting from seed — is easier than it looks. It also comes with great benefits, especially if you want to start an organic garden and have full control of how your plants grow.

When you opt for seeding, a whole new world of options opens up as you can find any plant species your gardening soul dreams of. You also get to pick a high-quality potting mix — or create your own — and select the growing container where your little seeds will start sprouting.

If you have no idea where to begin, we’ve created this step-by-step guide to give you a head start on this type of gardening. You’ll learn how to begin seed starting indoors, including useful tips and tricks that will help you overcome any challenges that might arise.

Basic Equipment for Seed Starting

For gardening newbies, it can be very tempting to opt for a seed starting kit, which is commonly found in the aisles of your local garden center. While these options are convenient for beginners, they tend to be made of plastic and other non-eco-friendly materials.

Creating your own sustainable seed starter kit is easy, affordable, and a great way to make sure you’re giving your plants the healthiest growing environment for them to thrive. A basic seed starter kit should include the following items:


There are plenty of seed options with different price ranges, but they’re generally quite affordable. You should have no issues getting high-quality organic seeds at an excellent price.

If you’re looking for the ultimate super seeds, check out organic heirloom varieties. As the name suggests, heirloom seeds are old types of seeds resulting from open-pollination by insects, birds, wind, and other natural methods. They are always non-GMO and produce plants with superior taste and high nutrition levels.

One of the best things about starting with seeds is the wide variety of species you can add to your garden, which sometimes aren’t easily found as young plants (seedlings). Plus, one seed packet with at least a dozen seeds is cheaper than a single seedling.

If you’re planning to start a veggie garden, there are a couple of things you should keep in mind. While most vegetables can be started indoors, root vegetables — such as potatoes, beets, onion, and garlic — are best started outdoors in the gardening container where they’ll thrive as adult plants.

The reason behind this is that these veggies don’t like having their roots disturbed, and most won’t survive transplanting, which is the act of moving your baby plants to larger pots. All other plants, such as aromatic herbs, leafy veggies, and fruits (like tomatoes and cucumbers) can be seed started indoors.

Seed Starting Trays

Seed starting tray and small pots with seedlings

If you do a quick online search about seed starting trays, you’ll find an abundance of options made from different materials. If an organic garden is your goal, avoid plastic growing trays. They may contain harmful chemicals, such as BPA, which can end up leaching into the potting soil and eventually into your beloved baby plants.

Coconut coir pots or peat pots are an eco-friendlier and healthier option to plastic trays. These products are made of sustainable and biodegradable materials that support your delicate young plants’ growth and avoid the need to pull roots when it’s time to transplant. All you need to do is plant the whole thing inside a bigger pot and add your potting soil mix choice.

A surprisingly efficient (and ultra-low-cost) growing tray option is repurposed cardboard egg cartons. Just make sure you make mini-drainage holes using a needle to avoid water logging your plants. Once germination occurs and the first true leaves appear (i.e., the second set of leaves to pop up), you can use a pair of scissors to separate the egg carton cells.

Transplant your baby plants into a larger container or pot until they grow into young seedlings and then move them outside once the outdoor conditions get warmer.

Growing Medium

Now that you’ve picked the seeds and their housing, it’s time to select the soil where your plants will grow.

If you’re investing in good-quality organic seeds, you’ll want to get an organic potting mix. Specialized gardening brands offer an array of potting mixes explicitly tailored for seed starting.

A high-quality seed starting mix should be:

  • Light soil to allow appropriate (but not excessive) drainage and good air circulation — this supports root growth and prevents damping-off plant disease, which is caused by a fungus that may occur from overwatering and water logging.
  • Rich in organic matter to promote proper plant nutrition. Some things to look out for include earthworm castings, bat guano, or crab meal. Expert gardeners consider these elements to be outstanding plant food.

Note: Most potting soil mixes also include perlite and vermiculite to support proper aeration and moisture retention. These substances are naturally found in nature but are not renewable resources. If you’re trying to introduce sustainability into your garden, you may want to avoid them.

If you’re unsure which soil to go for, reading the back of your seed packets can help you decide. They provide useful information such as sun preferences, water needs, sowing depth, and appropriate spacing between seeds when planting.

Optional Items

Plant grown in a can under a desk lamp

Although you can successfully start seeds with just the three items mentioned above, there are a couple of other things that can speed up the germination rate of your seeds. This is especially true if you live in a cold climate and can’t provide your plants with enough warmth to kick-start the sprouting process.

Be aware that plants need six to eight hours of sunlight daily, and the optimal temperature for seed germination is between 65° to 75°F. If your house cannot provide these conditions, here’s how you can support your plants:

  • Grow lights: If you live in an area with long, dark winters, your plants may suffer from a lack of sun exposure. Consequently, they may end up “leggy”— flopping fragile stems that don’t support the plant properly. Getting a grow light can be a game-changer not only for people who live in colder climates but to any plant owner. Grow lights encourage plants to grow “bushier” and more vigorous.
  • Heat mat: Heat mats are fantastic additions to cold houses. They consist of synthetic sheets embedded with heating components and usually raise the soil temperature by 15°F. As an alternative, you can place your seed starting trays on top of your fridge or water heater, where the temperature is usually warmer.

When To Get Started

The goal of seed starting indoors is to get them ready to move outdoors once the weather begins to warm up. But before you start seeding, consider the following:

  • Your average frost date: When you select the plants you want to grow, you may notice that most seed packets advise you to sow them some weeks before your last frost date. If you have no idea when that is, use the Back to the Roots grow calendar to find out.
  • The plant’s growing season: While some plants, like tomatoes, cucumbers, and peppers, are summer species, others such as Brussels sprouts, onions, and cabbage thrive in colder temperatures. You can find this information on the back of your seed packet.

How To Get Started With Your Seeds

Seed starting tray with other tools on top of a wooden table

Now that you have all the elements to kick off your first seed starting attempt, it’s time to roll up your sleeves and actually get started.

  1. Place your growing tray on a flat surface and add some seed starting mix.
  2. Using your thumb, make a shallow depression in the soil. If you’re wondering how deep you should plant your seeds, a good rule of thumb is two or three times as deep as they’re wide. When in doubt — as always — check the seed packet.
  3. Sow seeds knowing that some may not end up germinating. Adding between two to five seeds is enough to cover your bases but not overcrowd the cell tray.
  4. Gently skim some soil over the seeds, just enough to lightly cover them.
  5. Place your growing tray inside a plant saucer, large dish, or baking tray. This will be helpful when you hydrate your plants — more on that below.
  6. Water your seeds using a spray bottle or by adding water to the saucer of your seed starting tray. Most experienced gardeners swear by the second watering method, as it helps them water the plants with minimal disturbance to the seeds while keeping the soil surface dry to avoid possible diseases. Avoid using a watering can at this stage as the force of the water might dislodge the seeds.
  7. Place your baby seeds on a sunny windowsill, preferably on a south-facing window for optimal sun exposure.
  8. Check your baby plants frequently to check their growth. If you’re not sure whether they need to be watered, dip your finger into the soil a couple of inches. If the soil is dry, add more water. Be mindful of overwatering as it could cause your plants to develop diseases.
  9. Once the first true leaves show up and you notice that the roots start to become crowded — they’ll try to get out at the bottom of the pot — it’s time to move them to a larger pot. If you’ve timed your seed starting correctly, this means the weather is getting warmer, and your plants are ready to experience the great outdoors. However, if the temperatures are still relatively low, you may need to move your plants to larger indoor pots.
  10. Before you permanently move your seedlings outdoors, they’ll benefit from the process of hardening off. This consists of moving your plants outside for a couple of hours each day so they can slowly adapt to the conditions where they’ll live in the future. If you can’t do that because of cold weather, brush your fingers through their leaves a couple of times a day to simulate wind.
  11. Once the ideal outdoor conditions settle in, it’s time to transplant your young plants to their permanent outside homes. Be generous with the amount of potting soil you use to provide them a sturdy base to grow robust root systems. Water them abundantly but less frequently. If you give them a few sips every day, this may cause the roots to rise in search of water, and you’ll end up with a fragile, breakable plant.

Seed Starting Is Easy, Fun, and Extremely Rewarding

There’s nothing quite like watching a little seed you’ve sown come out of the ground. Something that once looked like a dry, lifeless small pebble turns into a green, vibrant plant full of potential.

Seed starting is a great way to boost your gardening confidence, especially if it’s your first time. For more helpful details about veggies and seed starting, check out our comprehensive guide to the easiest vegetables to grow for some inspiration.

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