How To Start Seeds Indoors – 12 Steps

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Starting seeds indoors can help you get ahead on your spring gardening season. With a bit of planning and supplies, your garden season can be off to a great success.

Use these 12 simple steps to start your own seeds indoors and save a money on the budget while doing it.

Deciding whether or not to buy seedlings (‘transplants’) at the local nursery is the first things that should be considered when planning the spring garden.

If you are a beginner at gardening, the first couple of years may be better if you buy from the local nursery. Both options has its advantages and disadvantages.

Why Start Seeds Indoors?

• You are limited to growing only what vegetables or flowers you can find at your local nursery. Whereas starting from seeds, the possibilities are endless. Seed companies offer free seed catalogs every year.
• Buying heirloom seeds is often much cheaper that buying seedlings. Just compare the cost of a single tomato plant to the cost of a pack of tomato seeds.
• When you buy transplants, you have not control over how the seeds was started. If you are trying to grow an organic garden, this could be a concern. With planting seeds, you know exactly how the seeds were germinated and grown.

By starting your own seeds, you’ll be able to have more variety and also have a chance to try new things without breaking the family budget. 

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Benefits of Starting Seeds indoors

Depending on what growing zone you live in starting your own seeds can be very helpful.

• If you live in a colder zone, with a shorter growing season, starting seeds indoors can help you to gain additional grow time for vegetables that require a longer growing season. Crops such as tomatoes and peppers take several weeks to mature and if frost comes early in your area, they may not have enough time to mature if not started inside and transplanted outside.
• Same goes for warmer areas too. If you start seeds indoors, you can give your plants a fighting chance to mature and produce before the summer heat stifles them and stops their growth.

12 Steps For Starting Seeds Indoors

1: Setting Up Grow Area

Do you need grow lights to start seeds indoors? For seeds to grow properly, they need 14-16 hours a day of light.  Growing seedlings in a south facing window is possible, but more than likely, they will not have enough light to grow strong and healthy. 

I built my own grow light system and put them on timer so I didn’t have to think about lighting. And I saved a lot of money too.  

2: Gathering Containers

What Kind Of Containers Do You Need For Seed Starting Indoors?  

You can start seeds in pretty much anything. It will need to have adequate drainage in the bottom.  Just make several small holes in the bottom with a drill bit or a screwdriver.  

You can use recycled items such as egg cartons, plastic yogurt bowls, or even toilet paper rolls and actual egg shells can be used. And both toilet paper rolls and egg shells are organic. So they will help to add a nice organic compost to your garden soil.

The first year I started seeds, I used a variety of recycled containers. Butter bowls, plastic cups and such along with shallow storage containers I picked up at the dollar store to hold the containers in. They were cheap to get but I found that since they didn’t “fit” well, I wasn’t able to start enough seed in the space I had on my seed starting shelves. 

By year two, I used seed starting flats and seed trays must say they worked great!  They are small, so you can start several seeds in a single flat.  They come with well fitting trays with out holes to catch water and they are just easier to work with.   

NOTE:  There is no need to block the holes in the bottom of the container.  Adequate drainage is needed.  

Of course, it was an investment, but by being careful with them and storing them properly, they can be re-used.  Just a note, for whatever you choose to use, be sure to wash them well in a hot soapy water and drain well before using.  

I store my seed flats in large clear plastic totes like this one and keep them on a shelf in the garage.   I use clear so I am able to see what is inside without having to take it off the shelf. This really helps with keeping my garden supplies organized and to see what I need to get when planning my spring garden each winter.

3: Seed Starting Mix

What Kind of Soil Should You Use to Start Seeds Indoors?

A word of caution, don’t use regular potting soil.  It’s too heavy, does not drain well and tends to get a hard shell on top when watered. Use a potting mix specifically for starting seeds is better. 

You can make your own using peat moss and equal parts of vermiculite and perlite.   This mixture will hold in moisture well, allow for great drainage and not be too heavy on top of your fragile seeds. 

If you make your own mixture, and it has not been sterilized, you can heat it in the oven at 200 degrees for about 30 minutes. This will kill off any bacteria that may be in it. Fresh sterile soil will give your seeds their best chance.

You can also purchase a seed starting mix that is sterilized and ready to use.  

The difference between potting soil and seed starting mix is that potting soil is just that – soil.  It is just a soil that is free of weed seeds and bacteria, but has no fertile factors to it.  

Potting mix is a blend of peat moss, vermiculite, perlite, and other finely chopped amendments, such as compost, that is designed specifically to give your potted plants nutritional value and a better chance at germinating.

4: Filling Containers

Before filling containers with a seed starting mix, you’ll need to do a couple things.

• Grab a good size plastic bucket such as a 5-gallon food grade bucket
• Pour in a small amount of seed staring mix and add warm water and mix. You will want it to be moist, not totally wet.  It takes a bit of time for the starter mix to “soak up” water to moisten.
• Now when filling your containers, use the “pre-moistened” starter mix.

Once starter mix is moist, fill containers to just below the rim.  

Press soil down gently, with your fingers, to remove any air bubbles.  This step makes sure to have enough starter mix in the container.

5: Planting Seeds

How Do You Start Vegetable Seeds or Flower Seeds Indoors? 

1) Place a hole the correct depth, according to seed packet instructions, in the center of container using a stick or your finger.   

2) Next, place 2-3 seeds into each hole and gently cover with moistened seed starter mix. Gently press seeds to make sure they have contact with the soil mixture. 

3) Now, use a spray bottle to spray to make sure the seeds are good and moist.

4) Lastly, wrap a clear plastic covering such as a plastic wrap or lid over the tray to hold in moisture.  This forms like a greenhouse to germinate your seeds.

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6. Adding Heat

Do You Need A Heat Mat to Start Seeds?  I’ve heard different discussions on the heat mat.  Many say they start seeds indoors without them.  It is true that seeds need a consistent temperature to germinate properly. 

However, I’ve not had much luck starting seeds without using a heat mats, so I use them. 

Not only do they keep the soil at a consistent temperature, they also help to “speed up the germination process.”   They work great and inexpensive!

7: Keeping Soil Moist

Watering seeds when starting them indoors can be a bit tricky.  I don’t advise using a water picture, jug or anything of this nature. It allows too much water to flow out at one time.  Seeds can drown. 

I use a spray bottle like this one and fill it with warm water each time I water. Never spray seeds with cold water.

Once the seeds sprout, you’ll need remove plastic covering and start watering from the bottom by pouring water into the flat trays.   The soil will soak this water up and feed the seedlings as they need it. 

This also strengthens the roots and forces them grow deep into the seed containers.  You can now begin using room temperature water. I keep a gallon jug sitting in the floor by my shelves.   

Soil only needs to be kept moist – not wet.  Mold will appear if soil is too wet. 

8: Fertilizing – When to Start

When seeds germinate, they first produce a tiny leaf called a cotyledons.   These are NOT their true leaves. Cotyledons all pretty much the same.  They serve to fertilize and feed the seedling in it first stages of growth.

You only need to continue to keep soil moist. Once the seedlings produce a second set of leaves, called True Leaves the cotyledon is no longer feeding it and you will need to begin fertilizing.

A light liquid fertilizer will do well. I use an organic diluted fish emulsion and seaweed fertilizer. It really stinks but works great!   

Mix a ½ ounce to one gallon of water.  Remember, the room temperature water?  Just add the fish emulsion to it and shake well.  Be sure to keep a lid on the jug, as I said, it stinks.

9. Thinning – How and When

Since planting 2-3 seeds in each container, it is necessary to thin-out seedlings once they produce their true leaves.  It’s best to wait until they have at least 2 sets of true leaves before thinning.  

And then you’ll want to carefully clip off, at ground level, the “smallest/weakest” plants with a sharp pair of garden snips, I use these. I know, it’s hard to waste a good seedling, but this will help the stronger seedling to grow even stronger.

Otherwise, they will be competing for fertilizer and could be stunted in growth.

TIP: Don’t pull these out of the soil!  This can very easily damage the roots of the seedling you are leaving in the container.  The snipped plant will die and not harm your largest healthiest seedling. The root will break down and an organic fertilizer to the potting mix.

10: Potting Up – How and When

As seedlings grow, they will need to be transplanted into larger growing containers.  Of course, there are larger seedling containers you can buy, or use a 16 oz solo cup. Whatever you use, it will need drainage holes.   

TIP: Solo cups do fit nicely into the leak-proof trays.  Whatever you choose to use, it needs to be washed well in hot soapy water and drained.  This is to wash away any bacteria’s that may be in the container.

As in STEP FOUR – moisten potting soil. Yes, you can transplant seedlings into a rich potting soil when transplanting.

Fill larger containers with moist potting soil to just about half-full.  Leave enough space for when the root ball from smaller container is set inside it, the soil level is even with top of the of the larger container.    

Tips for Removing Seedlings From Trays

1). First, water generously from the top with a warm water. Make sure seed starting mix is evenly moistened and water drips out of the bottom.

2). Next, gently with one hand, squeeze container to loosen soil from sides of container. Be careful not to cause the soil to break apart.  

3). Lastly, when squeezing on container, carefully tilt it onto its side, and use other hand to catch it as it slowly slides out. Do not pull on the seedling and use caution not to injure the seedling or the root ball.  

Now, gently place root ball into the center of your larger container and fill moist potting mix in and around root ball to hold it in place.  Gently tap soil to pack place firmly in place.

Water well to make soil moist, as soil settles and air pockets are filled, add more soil.   Container needs to be filled up to 1/2 inch from the top without air pockets.

The 1/2 inch will allow for watering as the plant continues to grow.   Place back on shelf under grow lights.  

TIP: It’s also at this time, that I put a fan in the room to gently blow on the seedlings.  This helps to strengthen stems.

Just place it across the room, a few feet away, and allow it to, very gently, blow toward seedling. Use the lowest setting on your fan.   A basic desk top fan or pedestal fan will work great.   

11: Hardening Off

Your seedlings have been spoiled by artificial light, heating pads and regular waterings for several weeks now. This is nothing like the weather outside will be. So it requires they be “hardened off” before being transplanted outside in the garden.  

Hardening off means to gradually move plants outdoors to help them become accustomed or acclimated to harsh sunlight, winds, cold nights and less frequent watering.  This process will take 10-14 days. 

Ideally, expose them to the outdoors gradually.   Carry them outside in their trays and sit in a safe place a way from animals or damage.  Not in direct sunlight at first.

Begin with a couple of hours and increase over the duration of 10-14 days. Increasing time outside and watering less and less by the day.  On day 13 and 14 seedlings should be outside 24 hours without being taken back inside.  

They are now hardened off and ready to transplant into the garden.  

12: Transplanting Outdoors

Garden soil should be prepped ahead of time by adding organic amendments such as this DIY calcium powder.   This will help to encourage growth of organisms to make seedlings grow strong and healthy. 

Before transplanting seedlings dig a deep hole and add organic amendments.  Make it deep enough for root-ball to be level with the surface of the surrounding garden soil.  Fill hole with water.

There is an exception for tomatoes, read more here.

Next, gently remove root ball and seedling from container and carefully place it in the hole.

Fill hole back in with soil.  Gently press down to make sure soil has good contact with root ball.  This will help it to grow straight and tall.  Slowly water generously to make sure water is soaked into the bottom of the hole through all the soil.  

Spread mulch around your newly transplanted seedling to hold in moisture and keep area free of weeds.  

Additional Tips to Give Seedlings A Best Chance 

• Timing is important. Seedlings need to be transplanted after threat of frost has past.  You can learn frost dates for your zip code, by looking at the USDA Plant Hardiness Map. 
• When to plant outdoors. Learn more about how soon to plant spring vegetables and feel free to print and use this spring garden checklist when getting ready to start a garden.  
• Transplant seedlings on a cloudy day. This will help protect them from sun scorch.  New seedlings need to be protected from harsh sun rays for several days.
• Protect plants from heavy winds.  Since they have just been planted, the roots are not bound securely in the soil.  

It sounds like a lot, but it is not as difficult as it may sound. With just some simple supplies and following these steps, you can start your own seeds indoors this garden season.

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