An Introduction to Seed Starting for Beginners

As backyard gardens continue to grow in popularity during the age of Covid and amid fears of food insecurity, we thought it was the perfect time to teach some new future backyard farmers how easy it is to start seeds indoors in order to grow your own food! Enjoy!

What is seed starting?

Seed starting (indoors) is the act of sowing seeds inside your home, green house or other shelter in order to provide a protected (controlled) environment to allow your new (future) plants to thrive. You can control the soil you use, the amount of water you give, and the exact lighting conditions you provide. You can also control the exact soil temperature (with products like heating mats) to increase the percentage of seeds that germinate.

Seed starting indoors is a popular method that can lead to many healthy, fruitful plants later on in your backyard.

(A special thanks to GRO Big Red for the phenomenal seminar, as well as for their information).

What is germination?

In order to understand why we are starting seeds indoors and what we are trying to facilitate, it is important to glance quickly at the definition of germination before we move forward.

What seeds should you start indoors?

Not all plants need, or even prefer, to have their seeds started indoors. According to, arugula, beets, carrots, corn, cucumbers, green beans, kale, onions, potatoes, squash, and watermelons (to name a few) can be planted directly outside in the garden as seeds.

On the other hand, plants that benefit from seed starting indoors include tomatoes, basil, marigold and peppers. These are among the easiest ones for beginners to start indoors, according to

There are several more plants that do well when their seeds are started indoors. This includes broccoli, brussels sprouts, cabbage, cauliflower, celery, and eggplant (source:

What supplies you need to start seeds indoors

In order to increase your chances of success when you start seeds indoors, it is important to buy the right equipment. This will help you maintain a consistent environment for your seeds to thrive as they grow.

You will need:

1. Seeds you intend to plant -remember to research which plants need to be started indoors vs. which plants do not need it.

2. A seed flat (or several) to place your soil and seeds inside.

3. Germination mix -this is very different than traditional potting soil. It does not have the same nutrients that you would want for a garden bed, so stay away from fertilizers and products like compost for this step. You can also make your own germination mix with equal parts peat moss, vermiculite, and pearlite.

4. Pot labels or plant markers so you can tell which plant is which as it grows.

5. Seedling heating mat -this is in order to maintain a soil temperature of around 75 F as your seedlings grow.

6. Soil thermometer -this is to track your soil’s temperature to make sure your heating mat is doing its job!

7. Grow lights -You can opt to omit grow lights but they do seem to increase your yield if used properly.

What do seeds need in order to germinate?

Thank you for GRO Big Red for this information from their recent presentation!

1. Water: germination begins with imbibition (think ‘drinking’) or through absorption of water, which in turn starts a chain reaction through hormones and chemicals that ultimately allow the seed to start growing. Once the seed is wet, do not let it dry out! If you forget to water for a few days and your seeds dry out, that could be the end of all your plants for good!

2. Oxygen: Even in storage, seeds require oxygen. Respiration actually increases during germination! When seeds get wet and germination starts, there is a quick uptake of oxygen. Because of this, seed starting material (soil) needs to both retain water and remain light and fluffy to allow oxygen to circulate.

3. Soil (or ‘media’): Your soil needs to be fine, uniform, well aerated, and loose. Seed germination requires a lot of oxygen so we don’t want to use heavy, compacted soil. The soil you use for seed germination needs to be free of insects, disease, and any weed seeds. You don’t want to use anything with bacteria or fungus potential. Believe it or not, you want low fertility at this stage, so stay away from fertilizers and compost. The seeds already have enough ‘food’ inside of them to produce up to the first set of ‘true leaves’, so nutrients and ‘food’ are not needed to feed the plant to get it to grow. After the seedling reaches this stage, the nutrient requirements change. For seed starting, a good recipe is equal parts peat moss (add agricultural lime to buffer the pH levels) or coconut core, vermiculite, and perlite.

4. Temperature: Each seed is different in its temperature requirements. However, for most seeds to grow, the ideal soil temperature is around 75F. This is when seeds have the highest percentage of successful germination. It is more efficient to heat the soil in your seed starting tray, rather than the entire room your seed trays reside in. Therefore, people often use seed heating mats. Stay away from heating vents in your house to heat your seed starting trays as this can dry out your soil and kill your seeds. Please research the ideal soil temperature of each seed you plan to start indoors.

5. Light: Believe it or not, some seeds require light to germinate, while others do not. The way you can tell the difference is by reading the seed packet or doing research online. If you are told to bury the seed, that means it does not require light to germinate. On the other hand, if you are told to place the seeds directly on top of the soil, they do require light. For example, a lot of lettuces require light so you typically sprinkle those seeds on top of the soil. Tomato and pepper seeds need to be buried, so therefore they do not need light to get started. Supplemental light does seem to improve germination success in most cases so we encourage you to look into grow lights. Most seeds need light after they germinate. You will usually continue to grow these plants indoors for 6-8 weeks. A sunny window might work but grow lights will work much better.

A Basic Step by Step Seed Starting Process

1. Buy seeds that prefer indoor seed starting, along with supplies listed above

2. Assemble supplies and test seed heating mat and soil thermometer

3. Mix germination soil mix and fill cell packs

4. Plant seeds according to instructions on seed packet

5. Label cell packs so you know which plant is which!

6. Place cell packs in drainage tray

7. Water the seeds in very lightly so as not to disturb the seed

8. Cover trays with humidity domes or plastic wrap

9. Turn on seed heating map

10. Turn grow lights on timer

11. Check daily for germination

12. Water regularly

What do I do after my seeds sprout?

After your seeds pass the germination stage and produce their first set of ‘true leaves’ (or pair of leaves that grow after the two seedling leaves), it is time to transplant it to a new tray with more space and different soil conditions. This is a great time to add an organic, eco-friendly fertilizer like frass, which will provide your seeds the nutrients they need to prosper and will boost your plants natural immune system. After growing in this place for several weeks (depending on the plant), it will be time to transplant this young, healthy plant to your outside garden.

Good Seeds vs. Bad Seeds

Before you start seeds indoors, it is important to know how to distinguish good seeds vs. bad seeds. Seeds don’t last forever, especially when their surrounding environment changes over time. You can actually tell if a seed is viable by doing a ‘float test’. This is where you place multiple seeds in a cup of water. The seeds that float are still viable, whereas the seeds that sink will most likely not grow.

Frequently Asked Questions

- Can you start seeds in potting soil?

According to, potting soil can be used for seed starting, but it is not recommended. This is because potting soil may contain unnecessary fertilizer which can burn the delicate seeds. Seeds also may need to work a bit hard to push up through potting soil. Potting soil is better utilized for the next stage in this process, after the seed germinates and produces true leaves. At this point, you can transplant to a larger container and utilize different media like potting soil.

- What should I feed my seedlings?

As you may recall from a previous section in this article, seeds themselves do not need fertilizer while they initially germinate. There is already enough nutrient content within the seed to allow it to grow into a seedling with its first pair of true leaves. After that, however, your seedling will require additional food. According to, a week after germination, seedlings require small amounts of Nitrogen, Phosphorous, and Potassium. Mealworm frass is a great source of these nutrients.


Starting seeds indoors can be daunting at first, especially to first time backyard gardeners. However, with a little practice and a lot of patience, you can produce some truly amazing, tasty food for you and your family. We hope this article helped answer some common questions you may have. Happy gardening!

Make sure and visit our shop and see all our great organic gardening frass!

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