When and How to Start Seeds Indoors

When and how to start seeds indoors.

One of the best parts about farming, gardening or homesteading is growing plants from seeds.  When I was teaching high school agriculture, it never ceased to amaze me how many of my students had never watched a plant sprout from a seed.  It's such a simple thing, but it can really be extraordinary to see, especially if you've never done it before.

​I'm going to walk you through everything that you need to know in order to start seeds at home.  It's simple and anyone can do it!

​🤚Before we dive in, I want to give you a FREE guide that will help you grow your best garden yet! Grab your free copy of the From Seed to Supper guide here and grow a bountiful garden this year!

Why start seeds indoors?

There are several reasons why you should be starting seeds indoors!  Read my post 5 Benefits of Starting Seeds to see my favorite reasons for starting seeds at home.

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You'll get healthier plants.

This may seem shocking, especially if you're worried whether your seeds will actually sprout or not.  I get it.  It can be intimidating to start seeds for the first time.  There seems like there's a lot that could go wrong and occasionally, it does.  BUT, let's put it into perspective real quick.

Let's say that you start an entire packet of tomato seeds.  That's usually about 40 plants.  Unless you're growing tomatoes to sell for profit, that's probably wayy too many tomato plants.  You'll think out the slower-growing and weaker seedlings as your plants get older.  If you only need 5 or 10 tomato plants, you'll choose the healthiest plants to grow in your garden.

​If you were to go to a garden center, you're going to pick out the healthiest plants they offer.  But, you won't be able to tell if these plants were the strongest and healthiest of their fellow seedlings or not.  You may think that you're buying a strong and vigorous plant, only to have it be a slow grower that doesn't produce much.  You can tell so much more about the health of your plants when you start them from seeds.

how and when to start seeds indoors

It's cheaper!

Most gardeners, farmers and homesteaders want to do things cheaply and frugally.  I mean, that's part of the reason that you want to start a vegetable garden, right?  Why not save even more money by starting your own seeds?

​I'm going to use tomatoes as another example.  Let's say that you purchase a couple of tomato plants at your local garden center.  Depending on the variety and size of the plant, they will cost you anywhere from $3-10 EACH. 

For two plants, you're looking at spending somewhere between $6-20!  You can buy a packet of tomato seeds that has about 40 seeds in it for around $3.  Even if you don't use all of the seeds and only sprout 2 plants, you've saved money!  To make it even cheaper, consider splitting seed costs with a friend.

A bigger variety is available.

When you buy plants from a local garden center, you'll be limited to the plants that are available at your local garden center.  Usually, garden centers carry the best-selling varieties.  If you're looking for heirloom crops, varieties that are resistant to certain pests or funky varieties, you may be disappointed.

​When you buy seeds through a seed catalog, you'll have endless selections of seeds to choose from.

Which seeds should you start indoors?

You can start seeds for almost anything at home!  Herbs, vegetables and bedding plants can all be started at home.  If you can purchase it at a garden center, you can probably get seeds to start it.

Some of the most common seeds to start at home are:

-leafy greens

​Some seeds for leafy greens, flowers and herbs are really small, which makes them harder to sow.  To make it easier on yourself, you can use a tool called a seed dispenser that can help separate tiny seeds.  Most vegetable seeds are large enough that they are easy to grab with your fingers and sow them.

What you need to start seeds

You can purchase miniature greenhouses, heating pads, grow lights and all sorts of things to start seeds, but you don't need any of that!  Consider those luxury items.  If you want to invest in them eventually, you can and they will help, but you definitely don't need them to grow a ton of healthy seedlings.

You'll need:

Seed starting trays or peat pots

Seed starting mix


Seed dispenser (for tiny seeds)

Plant labels

​A sunny spot

Seed starting mix

This is probably one of the most important items on here. Make sure that you are using a seed-starting potting mix, not normal potting soil.

how and when to start seeds indoors

When seeds sprout, the roots and stem that emerge are fragile.  They can't push through compact, tough soil the way that mature plant roots can.  Normal potting mix is designed for mature plants, not tender seedlings.

​Seed-starting mix is designed to be soft and easy for young plants to grow through.  It also holds enough water without drowning the plant.

Pots or trays

There are multiple kinds of trays and pots that you can use to start seeds.  It's possible to start seeds in many different containers, but there are two different kinds that I would recommend if you're new to starting seeds.

You can purchase seed-starting trays or cells.  Most seed starting trays and cells are plastic and can be reused year after year if you take good care of them.  I've got several seed-starting trays that I've been using for over five years now that are still in really good shape.

​There are also seed starting trays and pots that are made from materials that break down.  These are really convenient and make transplanting easier.  The downside to these is that you can't reuse them and therefore they tend to become more expensive to use over time.

When you're buying seed starting trays or pots, check for two things:

1. Buy seed starting trays that are broken up into smaller cells.  Large seed starting trays that are flats make it harder to transplant the seedlings when it comes time.  I've found that the seedlings grown in seed starting flats are often pulled out of the soil and the roots can become damaged easier.  When the flats are broken into cells, the roots grab onto more soil and transplanting doesn't damage the roots as much.

​2. Make sure that the cells or pots have drainage holes.  Many seeds that germinate die because they are in soil that is too wet.  Plant roots need oxygen in the soil, not just water.  Too much water can cause the roots to rot and die.  Drainage holes will help prevent your seedlings from being in soil that is too wet.

Light and water

Light and water are crucial to successful seed starting.  Not enough light or water will stunt seedling growth or prevent it.  Too much water can drown plants.

​If your plants don't have enough sunlight, they will stretch and become leggy.  Leggy plants have elongated stems and bend towards the sunlight.  The best place to put seed trays is in a sunny window.  Windows facing the south or west are your best bet.

how and when to start seeds indoors

Artificial light can help, but the best light is natural light.

Sunlight also helps to warm the soil.  Most seeds won't germinate if the soil isn't warm enough.

Be careful when watering your seedlings.  Seedlings are fragile and can be damaged easily, even during watering.  The best way to water seedlings is with a misting spray bottle until they are large and tough enough to transplant.

Water seedlings daily to keep soil moist, but not saturated.  Remember, seedlings are subject to developing root rot if the soil is too wet.  Check the moisture content of your soil by gently poking your finger into it.  The soil shouldn't feel soaked through.  If the top of the soil is dry, water it.

Make sure that your seedlings are able to drain properly.  Seed starting cells and trays should have drainage holes in them to allow excess water to drain out.  It's hard to prevent saturated soil when the pots or cells don't have drainage holes.

​Cells or pots that don't have drainage holes will hold water in the bottom of the container.  When you check the moisture level, you may think that they need water since the top of the soil may feel dry.  Eventually, this will lead to the soil becoming soaked and essentially drowning the roots of the seedlings.

When to start seeds indoors

Different seeds will need to be started at different times.  When you're trying to determine when to start seeds, you'll need to think about when you would plant the seeds in the ground and the amount of time that plant needs to germinate and become tough enough to transplant.

Checking your calendar

The first thing that you want to do is determine when your average last frost date is.  You may not be able to find your exact city, but you can locate a city that is close to you through the Farmer's Almanac.  You always want to plan on planting seedlings in the ground after your average last frost date.  Most seedlings won't survive if they are hit by a frost, so plan on planting after that date.  Once you've gotten your last average frost date, get your calendar out.

​Work backwards from your last frost date.  Depending on the seeds that you want to start, you'll need to count backwards anywhere from 2-8 weeks.

Should you make adjustments?

You may need to adjust when you start seeds.  If you plan on growing plants indoors or in a greenhouse, you can start seeds all year long since the outside growing conditions will not affect your plants.

​Leafy greens and other cool weather crops will go into the ground when the weather is cooler.  Lettuce and leafy greens will bolt if the temperatures are too warm.  Avoid this by starting seeds to plant them in the ground when the temperatures won't go above 70 degrees F.

how and when to start seeds indoors

How to start seeds indoors

Starting seeds indoors is really easy.  Once you've gotten your date to start seeds, get your materials together and your seeds.

You can go ahead and fill your seed cells or pots 2/3- 3/4 of the way full.  Don't pack the soil down; you want it to be somewhat loose for the seeds to germinate.  Once your soil is ready, you can sow seeds.

There are two ways that you can sow seeds.  Either way is fine, just use the method that's easier to you.  You can either sprinkle the seeds on top of the soil and then cover them with a light layer of soil, or you can make a small indention with your finger, insert the seeds and then cover them over.

Check the packet for your seeds and see how deep they should be sown.  Seeds that need to be sown deeper (1/2" or so) should be pressed into the soil with your finger.

​Once the seeds are sown and covered, use a water bottle and thoroughly wet the soil.  Don't apply fertilizer.  The seed itself has the nutrients that the developing seedling needs to emerge and grow.  Once the seedlings are 7-10 days, you can add a fertilizer.  If you add fertilizer too soon, you risk burning the tender developing roots and stems.

It's a good idea to label your seeds, even if you only start a handful of plants.  It can be difficult to identify seedlings.  Labeling them makes it much easier to keep up with.  This is especially true for flowers and herbs, which can appear quite similar until they are older.

Place your seed trays or pots in a warm, sunny area.  Don't put them outside unless the night temperatures aren't going to dip below 70 degrees F.  A southern facing window is the most ideal spot.  A west-ward facing window can also provide good sunlight.  The more direct sunlight that the plants can get, the healthier they will be.  If you notice your seedlings are starting to stretch and become leggy, move them to a sunnier location.

​Water your seeds and seedlings every day. Check the moisture levels of your soil and make sure that the soil is draining properly.

Tips for Starting Seeds Indoors

how and when to start seeds indoors

When you sow seeds, place 2 seeds into each cell or pot.  Not all seeds will germinate, so it's a good idea to put two seeds into each space in case one doesn't germinate.  If both seeds germinate, don't worry.  That's ok too!  Most plants won't be too crowded by having two seeds in one cell.

Leafy greens like lettuce or cabbage should be thinned more than other vegetable plants.  You may end up with more seedlings than you want to plant.  If that's the case, thin your plants.  Gently pull up the weaker, smaller plants and leave the healthier plants.

Be specific as possible when labeling your seeds.  If you plant multiple varieties of the same plant, you'll want to know which ones are which.  I've been guilty of this myself.  One year, I started seeds for several kinds of peppers.  I wasn't thinking that it would matter, so I simply labeled them as peppers to distinguish them from my other vegetable plants.  When it came time to plant them in my garden, I didn't have a clue which plants were jalapenos, sweet banana peppers, hot banana peppers or bell peppers.

Some seeds germinate much faster than others.  Leafy greens germinate really fast, sometimes in as little as a couple of days.  Vegetable plants usually take longer to germinate than herbs or flowers, so don't freak out if yours aren't showing up after a couple of days.  Keep watering them and they will show up.

Buy the freshest seeds possible.  Seed packets have expiration dates printed on them.  Choose the seed packets with the expiration date that is the furthest out to get the freshest seeds possible.  The older seeds are, the more the germination rate drops.  To get the most seeds to sprout, use the freshest seeds.

You can increase the germination rate for your seeds by soaking them the night before you plant them.  Don't leave seeds soaking in water for more than overnight since that reduces the amount of seeds that will germinate.  The day before you plan to sow seeds, you can place them in a bowl of room temperature water.  If you're planting more than one kind of seed, make sure to label them so that you know which ones are which!

Moving seedlings outside

When it comes time to move seeds outdoors to your garden or container, you'll need to harden them off first.  Your seedlings are going to get spoiled inside in the warm and sunny window.  You'll need to prepare them to living outside where the temperature can fluctuate more.

​To harden off seedlings, start introducing your plants to the outside a little at a time.  For the first day, introduce them outside for an hour and then bring them back in.  You want to gradually work them up to being outdoors over the course of a couple of weeks.  You'll also want to reduce the amount of water and fertilizer that you provide to mimic the way that you'll water and feed them when they are planted outdoors.

​If you haven't yet, grab your FREE copy of the From Seed to Supper guide and learn how to start growing delicious, fresh vegetables and herbs!

starting seeds indoors, free guide to growing vegetables

Check out these other gardening posts:

Are you starting seeds at home? What's your favorite way to start seeds indoors? Let me know below!

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Hey, I'm Shelby!

Founder of Garden. Farm. Thrive.

I'm a multigenerational homesteader, former high school and college agriculture teacher, and your guide for embracing a simpler, more traditional lifestyle. Come along as I teach you how to grow your best garden, raise chickens and other livestock, learn traditional skills and create the homesteading haven of your dreams.

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