Starting Seeds Indoors: Six Steps to Spring Gardening

With spring on the horizon, there is something magical about starting your garden seeds indoors and the excitement of the growing and gardening season ahead. By starting seeds indoors, and nurturing them into seedlings, you see the realities of your garden begin and realize you’ll be ready for spring before you know it.

In this Article:

  • Benefits of Starting Seeds Indoors
  • Timing for Seed Starting
  • Which Seeds to Start Indoors
  • Essential Equipment and Supplies
  • 6 Steps to Starting Seeds Indoors
  • Caring for your Seedlings
    • Watering
    • Lighting
    • Fertilizing
  • Transitioning Seedlings Outdoors
  • Sustainable in Seed Starting
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Seed Starting Definitions: Before we sow our seeds, there are a few terms that may be new to some gardeners. We’ve done our best to define these terms so there are easily understandable to all.

  • Saving seeds is the process of saving seeds from last years vegetables and flowers grown in your garden.
  • Damping-off disease is the rotting of the stem and roots at and below the soil line from over-watering and not enough air circulation.
  • Hardening off is a 10-14 days process of acclimating seedling to the outdoor eliminates like wind, rain, sun and changing temperatures.
  • True leaves: Seedlings have two types of leaves: seed and true. Seed leaves are the first two leaves that pop up–officially called cotyledons and they store food for the seeds. True leaves emerge after and the plant can now start to generate energy through photosynthesis (the process plants use to make their own food).

Benefits of Starting Seeds Indoors

Starting seeds indoors isn’t just a hobby; it’s a strategic move with many benefits. Whether you’re starting this year’s vegetable garden or flowering plants for containers, or both, seed starting indoors brings many great reasons to do so.

  • Saves money: Seeds can be less expensive than buying seedlings from your garden center especially if you’re saving seeds from last year’s garden, exchange seeds with your community or an online seed exchange
  • Head start: While some gardeners stare outside wishing for spring to come, those that start seeds indoors get the pleasure of being ahead of the game and can look forward to the last frost date
  • Seed variety: Sowing seeds inside not only scratches the garden itch, but also gives you access to more varieties than the limited seedlings availability at the garden center.
  • Better germination and growth: By optimizing your growth conditions: light, moisture, and warmth, you can produce a higher rate of germination. By starting your seeds indoors, you decrease the potential risk from pests and disease brought in from outside sources.
  • Earlier and bigger harvest. By starting vegetable seeds indoors, you get more out of your harvest by transplanting the healthiest of plants as soon as the temperatures are warm enough, giving you a leg up on the growing season.
  • Reduces time and labor: Seedlings transplanted into the garden compete better with weeds than direct-sown seedlings decreasing time and energy spent on weeding and thinning.

Timing for Seed Starting

Timing is everything in gardening. Typically, you can start seeds about 6-8 weeks prior to the last frost in your area, but it is important to consider the plant(s) and your springs first frost-free date. Once you have your date, seed packets will tell you how many weeks to start the seeds before the frost-free date. Most seedlings are ready to go outside 4-6 weeks after you start the seeds.

Starting Seeds IndoorsWhich Seeds to Start Indoors

Not all seeds are created equal when it comes to indoor starting. Before you start planting seeds indoors, it’s best to know which varieties grow well, and later when transplanted and which seeds are best when sown directly outdoors after the last frost. It’s also recommended to use non-GMO organic heirloom seeds in your garden which can be saved and used year after year.

Best Seeds for Sowing Indoors

Brussel SproutsBlack-eyed Susan
LettuceMorning Glory
OkraShasta Daisy
This is not an exhaustive list. Research your plant choice to see if its a candidate for sowing indoors.

There are several vegetables that can be started indoors but must be transplanted carefully: celery, chard, cucumber, melon, peas, pumpkin, spinach, and squash. Veggies that need to be directly sown into the ground after the last frost-free date are beans, beets, carrots and corn.

Essential Equipment and Supplies

Every gardener needs a few supplies when starting seeds indoors – some of which you many already have. Whether you choose to go the DIY way, purchasing quality products or a little of both, you’ll be on your way to a great garden.

  • Seedling starting tray: One can go the DIY (egg cartons or empty toilet paper rolls) or store-bought choices – either way they do need drainage holes. You’ll also need a drainage tray and some type of plastic lid to keep moisture in. Some store-bought choices come with these and DIYers can use an old baking sheet and a plastic bag or wrap.
  • Seed-starting soil mix: Seed-starter mix is a lighter weight and airy soil for germination with higher percentages of nutrients needed. One shouldn’t use potting soil for seed-starting and vice versa.
  • Heat mat: Placing your seeds on a windows sill may product lanky and unhealthy seedlings. Most seedlings need between 70-75 degrees Fahrenheit consistently, so the Vivosun Waterproof Seedling Heat Mat makes good sense. Also, your seedlings should be placed in the warmest spot in your home away from cold windows and drafts.
  • Grow light: Seedling will need light for 12-16 hours a day. A grow light prevents seedlings from bending towards the window to get light. Either LED or Fluorescent lights are fine and the two we recommend depending on your set up are: i-Venoya 75w Grow Light or iGrowtek 2ft Grow Light for Seed Starting
  • Spray bottle: You can spray mist seedlings when the surface of the mix starts to dry out. Watering seedlings from the bottom up is best as to not over water them.
  • Plant labels: Good to have so we don’t forget what we planted. Used with a permanent marker to prevent information from being washed or rubbed off. Either popsicle sticks, reusable metal or plastic plant sticks work.
  • Seeds: Use your own saved seeds, purchase from your local garden store or reputable online seed company/exchange. Remember to use non-GMO organic heirloom seeds in your garden.

Also Read:

Six steps to Starting Seeds Indoors

Now that you have everything set up in its warm location, it’s time to get started.

Step 1: Use your hands to loosen up the seed-starting mix and fill a large bowl. Mix in water to evenly moisten the soil to a moist but not soggy consistency. (It’s recommended you wear a mask for this step as the soil is fine and can cause irritation.)

Step 2: Fill your seed tray or containers about three-quarters full. You want the soil mixture to be aerated and not packed down.

Step 3: Sow your seeds as per the instructions on the seed package. Seed planting requirements are different, but the rule of thumb is to plant seeds 2-3 times deep as they are wide—err on the shallow side if you are not sure. Cover seeds with more of the dampened soil. More than one seed can be pushed into a cell depending on the seed and cell size. Thinning of the seedlings may be needed later to prevent over-crowding and to give the seedlings the best chance to grow strong.

Step 4: Mist your newly planted seeds so the mixture doesn’t dry out.

Step 5: Don’t forget your seed labels. Being able to identify the seed and the date sowed allows you to know when they will be ready for transplanting.

Step 6: Move your seedlings onto a waterproof tray and a warm area under a grow lamp. To hold in the heat and moisture, add a plastic lid or loosely cover with plastic wrap. This provides the perfect growing conditions for the seedlings.

Caring for your Seedlings

This is the best but probably the hardest part – caring for your seedlings. It can be time-consuming but in the long run, very rewarding.

Lighting: Most seeds can germinate in total darkness or a low amount of light. If placed in a south-facing window, that is enough light until they sprout. Once sprouted, seedlings need much more light – about 12 to16 hours each day from a grow light. A timer is a good investment to turn the lights on and off. As the seedlings grow, keep the lights about 2-3 inches above the seedling without touching them.

Watering: Check the moisture of your seeds once or twice a day to see if they need misting – you don’t want the seedlings to dry out. You want the surface to stay damp but not too wet. When about two-thirds of the seedlings have sprouted, you can remove the plastic cover.

A full-on watering from below allows the seeds to soak up what they need through the drainage holes. Add a thin layer of water into your tray and let sit. Check the dampness of the top of the soil until its moist then remove the water. Too much water can lead to damping-off disease which can quickly kill your seedlings.

Fertilizing: Once the seedlings have produced two sets of “true” leaves, its time for a feeding. You’ll want to use a water-soluble, balanced fertilizer and dilute to one-half the normal strength and feed the seedlings once every two to four weeks.

Transitioning Seedlings Outdoors

Seedlings need a transition to the great outdoors–called “hardening off”. Hardening off is the process of gradually acclimating the seedlings to outdoor conditions like sun, rain, and wind for about 10 – 14 days. A seedling is ready for this process when they have 3-4 “true” leaves.

Each day move the seedlings to a shady, protected, outdoor location for increasing lengths of time. Gradually the outdoor time increases, and you introduce more and more direct sunlight. In the beginning the seedlings are brought indoors at night, or covered at night if temperatures get below 55 degrees Fahrenheit. Repeat this process until they thrive outdoors. They are now ready to transplant into your garden or containers. Water thoroughly before and after transplanting to help prevent shock.

Sustainable in Seed Starting

Sustainability is pretty mainstream these days – most everyone wants to know how to reduce their carbon footprint. As gardeners, we can take steps to find sustainable ways to start seeds that prove to be cost-effective, eco-friendly and reduce waste. Below are a few ideas to try for a more sustainable garden.

  • Starting Seeds IndoorsWhen possible, grow non-GMO organic heirloom seeds that can be saved and replanted each year
  • Use newspaper, toilet paper roles, or egg cartons (and eggshells) to make seedling pots or purchase our favorite: Daniel’s Plants Biodegradable Peat Pots Seed Starter Tray
  • Reuse takeout trays, open topped boxes as your seed tray. Poke drainage holes in the bottom and sow your seeds
  • Reuse plastic containers like yogurt, cottage cheese and sour cream containers
  • Recycle plastic pots from years before or from your neighbors and community
  • Purchase biodegradable peat pots made of natural materials that break down over time in the soil
  • Use an organic seed starting mix instead of a non-organic product
  • Make soil blocks with the Fiskars Soil Block Maker for planting seeds out of your soil mixture
  • Label your plants with popsicle sticks or reusable and weatherproof metal plant labels
  • Ditch pesticides and use organic fertilizers or better yet, make your own
  • Check secondhand stores, community gardening clubs, online give, and buy and sell sites to find supplies and tools

For items that are borrowed, used, or given, make sure to thoroughly clean and sterilize them to prevent the spread of any plant disease.

Final Thoughts

Starting seeds indoors is a rewarding and impactful endeavor. As winter drags on and on, beginning the seed-starting process can be therapeutic – planning your garden, getting your hands dirty, knowing the days are getting shorter and soon the temperatures warmer. Just writing about it makes me smile.

Whether you’re a beginner or experienced gardener, seed-starting is a great way to have flexibility in starting a variety of vegetables and flowers and a way to save money while you’re at it.

Starting Seeds Indoors


Q: Can I use regular soil for starting seeds indoors? A: While regular soil may work, using a sterile seed-starting mix ensures better germination and reduces the risk of diseases.

Q: How long should I leave grow lights on for seedlings? A: Aim for 14-16 hours of daily light exposure for optimal seedling growth, adjusting as needed based on plant behavior.

Q: Is it necessary to fertilize seedlings, and if so, how often? A: Yes, seedlings benefit from diluted, balanced fertilizer. Start fertilizing when the first true leaves appear and repeat every 2-4 weeks.

Q: What are the signs that seedlings are ready for outdoor transplanting? A: Seedlings are ready when they have developed strong stems and several sets of true leaves. Also, ensure outdoor temperatures are suitable.

Q: How do I prevent damping-off in seedlings? A: Damping-off is the rotting of the stem and roots at and below the soil line. To prevent damping-off, maintain proper air circulation, avoid overwatering, and use a well-draining seed-starting mix.

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Emma Smith

My research into learning more about flowering vines on a trellis became much larger when I happened upon vertical gardening and all the advantages and benefits. Whether you’re interested in outdoor or indoor gardening, read on as I share my acquired knowledge.

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