Indoor Seed Starting Guide - Our Stoney Acres (2024)

The basics of indoor seed starting are pretty easy to grasp. Really all you need is a container, some soil, and a light!

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Every gardener at some point decides to learn about indoor seed starting. Starting seedlings became more of an interest to us as the years went on and we got better and better at gardening our aspirations got bigger.

We wanted our flower beds to look nicer and we had varieties of tomatoes and other veggies that we wanted to try. Those new veggie varieties were not available at the local nurseries so we had to grow them ourselves. That’s when we began starting seedlings indoors.

Advantages of Indoor Seed Starting

1. Seedling Timing

The first reason I think you should grow your own seedlings is timing. If you have any interest at all in Year-Round Gardening, or even just getting an earlier start on the season by using cold frames, hoop houses, or water-filled cloches then you need to grow your own seedlings.

Let’s use early tomatoes as an example. You can use Wall O Waters to set out your tomato seedlings 6 to 8 weeks before your last frost date. But if you want a good selection of tomatoes to put out early your best chance is to grow your own seedlings. Most commercial growers just aren’t ready for tomatoes in your area extra early. So you need to grow your own.

The same goes for growing many of your favorite Brassica family crops in the fall. Broccoli, cabbage, cauliflower, Brussels sprouts, and kale usually aren’t available from commercial growers in the fall. So starting seedlings on your own means you can get these started just at the right time.

2. Cost Savings

Seed starting indoors also started to become a financial need. If you go through the list of veggies and flowers that we plant in our garden every year from seedlings the list gets pretty long.

For our little ¼ acre lot this year we will need right around 450 flowers and veggie starts. That can get super expensive. This is the main reason why we began starting seeds on our own. Even the smallest yard and vegetable garden can require 200 or more seedlings.

At $2.50 for a 4 pack of transplants that can get pretty pricey, very quickly. If you learn to grow your own seedlings you can save yourself hundreds of dollars a year. That is especially the case for those of you with large yards filled with flowers.

3. Greater Seed Variety

The 3rd advantage to begin indoor seed starting is seed varieties. There are hundreds of different varieties of tomatoes out there. They come in every color and shape imaginable.

But if you are buying seedlings from your local nursery then you may only have 10 varieties to choose from, and very few of those will be the extra delicious heirloom varieties.

Starting seedlings opens up a whole world of vegetable and flower varieties that you have never experienced before.

Basic Seed Starting Supplies

There are a lot of complicated methods for starting seedlings. Really all the different methods come down to just 6 simple things. The basic supplies for seed starting indoors are seeds, a spray bottle, seed pots, plant trays, soil, and lights. That’s it really, all the other things like heat mats, timers, soil blocks, peat pots, etc can help but all you really need is a container, soil, and light.

• Seed packets
• Spray bottle
• Plant Trays
• Pots
• Soil Starting Mix
• Lights

Seed Starting indoors is simple to learn how to do. It isn’t very expensive to get started either because there aren’t a lot of upfront costs if you just stick with the basic seed starting supplies in the list above. However, if you find you really like starting your own seeds and you would like to start more seeds then you could add extra supplies that would make it more convenient like a timer or a heat mat. If you would like to learn more about the benefits of a heat mat check out this article.

Indoor Seed Starting Pots

The most important thing to remember when choosing a container for starting seedlings is that it needs to have the ability to get rid of excess water. So basically it needs some drainage holes. Seedlings don’t like to be sitting in soaking wet soil. So when you water your seedlings any extra water needs to be able to drain off.

You can start seeds in just about anything that can hold some dirt and has holes cut in it for drainage. Over the years we have accumulated a big stack of seed starting containers and have used them all with varying success.

You can learn more about seed starting pots from this article. Anything from yogurt cups to rolled-up newspaper works. Soil block makers are also becoming very popular along with small peat pots and peat disks.

I love using the little 4 and 6 cell plastic packsthat you can buy at most garden supply stores. Or even better ask all your neighbors to save the ones they get when they buy nursery plants. These little cell packs are about the perfect size for nearly every seedling I grow, from flowers to veggies. I do like to plant my tomatoes in a slightly larger 3-inch pot but everything else goes in these beauties!

Seed Plant Trays

I put all of my seed starting pots into a larger plant seed tray Depending on what type of plants I’m starting I may water them by filling the larger container with water and letting it soak into the holes of the smaller pots.

So your larger container should hold water! I have found some trays at our local farm store that works pretty well. They are not quite as rugged as I would like but they are pretty cheap, so I’m using them for now until I come across a better option. Another great idea that I use is a boot mat tray. I just set my seed pots into this tray and it has been working well and does hold water.

Indoor Seed Starting Mix

The easiest way to get started growing your own seedlings is to just buy a good quality seedling mix from your local garden store. I prefer to grow all my veggie plants in a nice store-bought organic mix.

Look for a mix that is mostly peat moss with just a little compost and some perlite or vermiculite. I also try to use a mix that is sterile because those mixes tend to prevent the fungal infection “dampening off”.

You do not need to buy seed starting mixes that contain fertilizer. Seeds have all the nutrients in them that they need for the first few weeks of life. Later you will want to add some organic liquid fertilizer to your water to give the growing plants the nutrients they need.

If you are feeling adventurous (and you have space) you can make your own seedling mix. A simple recipe for a homemade mix is :

• 7 parts peat moss
• 1 part vermiculite
• 1 part perlite

Just mix the amount you need together in a big tub and away you go.

To learn more about making your own seedling mixes jump over to this post.

Whether you are using a store-bought mix or a homemade mix be sure to dampen it before you get started filling containers and planting seeds.

Seed Starting Lights

In order to be successful at starting seedlings, I think you need a nice 2 bulb fluorescent light. Some people start their seedlings in a south-facing window with direct sunlight, but I’ve always been disappointed with the results of window-started seedlings.

Instead, run to your local home improvement store and buy a simple 2 bulb “shop light”. They usually cost around $25 including bulbs. Don’t bother buying expensive grow light bulbs. Instead, just get a couple of cool white fluorescent bulbs and you will be good. LED shop lights are also becoming more popular and will work well for seed starting as well.

The more lights you have the more seedlings you can grow. So if you have space to hang 2 shop lights side by side you can get more seedlings going. Or if you are crazy like me and grow a million starts a year then you can have 4 or more lights.

How do you use Seed Starting Lights?

The most important part of lighting when starting seedlings is that you need to have the ability to get the lights very close (within an inch) of your seedlings. And then you need to be able to adjust those lights up and down. Keep the light about 1 inch from the tops of the seedlings as they grow.

So find a spot where you can hang the light with an adjustable chain or rope. I specifically built a seed starting shelf that I put all my seedlings on. However, you don’t need anything fancy, you just need a place to hang the shop lights and put the seeds on a table or counter. It is nice to have a timer to help with the hours of light needed for your seeds, but it isn’t necessary since you can set an alarm on your phone as well.

How to Start Seeds Indoors

Now that you know that seed starting really isn’t that complicated are you ready to get started? It is so easy to do and will make you feel so good that you grew your own starts this year. So let’s get into some more details about how to start seeds indoors. Here is a simple step-by-step guide you can easily follow to get your seeds started.

Step 1 Find seed starting Containers

Find some seed starting containers that have good drainage holes. Make sure the containers are clean and disinfected. Put your seed starting pots in a sturdy plant tray that will hold water.

Step 2 Add Soil

Fill the containers with premoistened soil nearly to the top. If you don’t add moisture to the soil before you put it in the containers you will have a hard time keeping the soil moist later on.

After filling containers with the soil press it down just slightly. You don’t want to pack it down super tight as this can affect root growth.

Step 3 Label your Seed Pots

This is an important step to remember with indoor seed starting because if you’re like me 2 seconds after you plant the seeds you forget what seeds you planted in which pots. I usually just put tape on my containers with the name of the plant. You can also use some popsicle sticks that you can write on and stick in the soil and reuse them year after year.

Step 4 Planting the Seeds

I simply place the seeds on top of the moist soil medium. I then add the prescribed amount of soil on top of the seeds and moisten lightly again with a spray bottle. Sow seeds at the right depth. You can find the right depth on the back of your seed packet.

However, as a rule of thumb plant your seeds 2 to 3 times as deep as the seed is wide. Once you plant your seeds get them right under the lights.

Step 5 Heat Mat (Optional)

A heat mat is also a good addition to your seed-starting operation. Learn more about the use of heat mats in this post. Although you don’t have to have one, they do help speed germination along. The heat mat warms your soil and makes the seeds germinate faster. Once the seeds have germinated be sure to remove the heat mat, leaving the heat on can cause your seedlings to get leggy.

Again a heat mat is not necessary, just helpful. Other articles suggest putting your seeds on top of the refrigerator but really, it isn’t that necessary. The first couple of seasons that I grew seedlings I didn’t have a heat mat or have them on anything warm and things were fine. Heat Mats cost about $15 to $30 depending on the size.

Step 6 Add Humidity

After planting your seeds put a layer of plastic wrap over the top of the containers, this keeps the humidity up. I take the plastic off as soon as the seeds start germinating. You can also use a plastic dome or humidity dome but I don’t particularly like them and since plastic wrap works just as well, why waste the money?

Step 7 Watering your Seeds

Be sure to keep the soil moist but not soaking wet. I usually use a spray bottle full of water to keep the surface of the soil moist until the seedlings have their first sets of true leaves.

Once the plants are established I will start watering from the bottom. As the plants get bigger their water needs will grow and you don’t want to be pouring water on the tops of the plants. Instead, keep the plant pots in a watertight tray and add about an inch of water to the tray. That water will then soak up through the drainage holes in the pots and gently water your plants.

Plan on watering the plants about every 3 or 4 days as they grow.

Step 8 Give your Seeds Light

Keep that light about 1 inch from the tops of the plants. You will want to run the light for 14 to 16 hours per day.

Step 9 Move your seedlings outdoors

In 6 to 8 weeks your seedlings will be ready to plant outdoors in the garden! These rules apply to most veggies and flowers. Take a look at your seed packages before planting to be sure your seeds don’t need any special treatment.

Before you move your seedlings outdoors to their permanent location you need to harden them off first. Hardening means slowly introducing your seedlings to outdoor conditions over the course of 7 to 10 days. You can learn more about hardening by watching this video I filmed.

There you have it, 9 simple steps to how to start seeds indoors. It really is not very complicated nor is it very expensive. It is so satisfying to watch your seeds grow and then be able to put those starts in the garden.

So why not give indoor seed starting try. Now there can be a lot more to it if you really want to have fun with it. You can use tons of different specialized containers, heat mats, timers, homemade mixes, and more. However, if you keep it simple you can get started this year!

If you would like to learn more about starting seedlings indoors, I would like to invite you to take my seed starting video course. The course is a little more than 2 hours worth of information on seed starting broken into nice bite-size segments. To learn more about this course you can follow this link.