Guide to starting seeds indoors – seed starting made simple

I am a member of many gardening groups, and around this time of year, many beginner gardeners stress about starting seeds indoors “the right way”.

This article will take a step away from impressive-looking photos and perfectly designed seed starting stations.

Instead, we will focus on getting you started with equipment and tools you probably already have or can buy at a small cost.

A step-by-step guide to seed starting for beginners

1. Getting everything together

  • Pot or container
  • A growing medium like potting soil or a coffee filter
  • A lid or a cover of plastic film
  • A source of light
  • Water and a spray bottle 
  • Seeds

For seeds to germinate and grow, you need to provide a growing medium, water, and for most seeds, light. 

Pot or container: Most of us prefer a pot or container, even though we could use a coffee filter, cotton balls, or another alternative.

But here today, we will use a pot or a container. My advice is to use a plastic container, as it will help keep the growing medium moist. 

Buy a seed starter tray or plastic pots, or use an empty food-safe plastic container. My simple rule for food-safe is that it is good enough for starting seeds if I get it from the supermarket. Empty yogurt containers are, for example, great.

Pots from peat and cardboard
Starter pots made from peat or cardboard retain very little moisture
Pots made from peat look great and have an all-natural feel. They do, however, dry out more quickly, and this adds an unnecessary layer of complexity. Also, I have taken the stance not to use peat moss anymore.

A growing medium: As for growing medium, I recommend using potting soil. There are many options, like coconut coir, vermiculite, coffee filters in zip-lock bags, and rock wool cubes, to mention a few. But keep it simple and buy a small bag of potting soil. 

Do not use regular garden soil. Seeds need loosely structured soil, and garden soil is too nutrient-rich and compact. Again, it makes the job at hand so much more complicated.
Good quality potting soil makes starting seeds an easier process
Good quality potting soil makes seed starting easier

A plastic lid or cover: If you buy a seed starter tray, it often comes with a plastic cover or dome. If you use a plastic container, cover it with plastic film. It’s that easy.

A source of light: Depending on the time of year, light can be as easy as natural sunlight. Place pots on a window sill and relocate them during the day to maximize the available natural daylight. Here more is better, though be careful during hot periods as the sun can get too intense, here indirect sunlight is better.

But more often, the problem is the lack of natural light. Especially when starting seeds in early spring or in winter. You have a couple of options, use your indoor lighting and accept that your seedlings may grow tall and leggy in their search for light. Or buy a grow light and give your pots about 14-16 hours of artificial light daily.

Grow lights are a good investment if you are serious about starting seeds indoors. But you do not have to buy an expensive grow light fixture to start seeds. To make it easy, look for LED bulbs with abouit 100 Lumen per Watt and a 3000 - 7000 Kelvin reading for your existing light fixtures. Ensure that the lamp reflects the light on to your indoor garden bed. After all, you do have lights on anyway during the darker times of the year. And white light works, if you want to avoid the blue or red disco feel indoors.

Water and a spray bottle: You probably already have a spray bottle at home. Just make sure it is clean. Buy a new spray bottle if you have used it for cleaning windows, glass tables, or even killing weeds with chemicals.

Seeds: Use fresh seeds. Do not fall for the temptation to use seeds found in a drawer in the house. Germination rates vary significantly from plant to plant, but be kind to yourself and purchase seeds from a reputable dealer. 

To summarize, go large or go budget. Start with coffee filters in zip-lock bags or potting soil in an empty food-safe yogurt container. Buy grow lights or bulbs for your existing lamp fixtures, or place pots on a sunny window sill. 

2. Planting the seeds

Before planting the seeds, you need to pre-moisten your potting soil.

You are looking for moisture, not wet soil. Here less is more. Imagine you are making a snowball from the potting soil. You should be able to make a ball that holds its shape on the surface of your palm. But the ball should easily crumble when you press it with your fingers.

When you have pre-moistened the potting soil, it is time to plant the seeds. Read the seed packet for planting depth, or use my rule of thumb and plant the seed two times the size of the seed.

Getting the planting depths for seeds right
Larger seeds are planted deeper, here coriander(cilantro) to the left and thyme to the right
Consider pre-geminating larger seeds like coriander (or cilantro). You can find some great tips in the article: 14 seed starter tricks to germinate seeds better

Smaller seeds like thyme and basil and scattered on the surface. Make a hole in the soil for larger seeds, place it at the appropriate depth, and then cover it with soil.

Do not sow too many seeds in each pot. Remember that each seed can grow into a mature plant. Depending on the size of your pot, anything from 5-10 seeds should be fine.

When seeds are planted, mist the surface and cover your pot.

Most seed trays come with a plastic dome or cover
Seed trays often come with a plastic cover, otherwise use plastic film

3. Placing the pot and container in a good spot

Most seeds need warmth to germinate. If you have a heat mat, great. If not, pick a surface that is not too cold. To give an example, granite tends to be cooler to the touch than a wooden table. A kitchen appliance generating heat or a window sill by a radiator are good options.

Many seeds need light to germinate. Use your grow lights or the available natural light to the best of your ability.

4. Misting your pots

Use your spray bottle to mist your pots to keep the soil moist.

There is no need to water the pots as you risk flooding them and displacing the seeds. 

Spray bottles ready for use in our kitchen
Spay bottles make it easier to mist the soil

The plastic cover will help keep the moisture locked in, and you will find that once every couple of days is usually sufficient.

Watch out for condensation on the inside of your plastic cover. When it happens, lift the cover to increase the airflow. Make holes in the plastic film or adjust the placement of your plastic cover to increase air circulation before you cover the pots again. 

5. What to do when you see the first leaves 

You know you are on the right track when you see the first leaves, cotyledons.

Remove the cover; now, access to light is more critical than ever. Place pots in a spot with plenty of light to help your new plants grow and develop.

Keep the soil moist, and be careful when you water the pots. Avoid getting the leaves wet; it is often easier to bottom water your pots.

Simply place the pots in a container with water and let the soil absorb the moisture it needs. Let the pot drain and run off any excess water before you place the pots back in their spot.

6. What to do when seeds do not germinate

Some seeds germinate in days, whereas others need weeks to show signs of life.

Basil and lettuce quickly germinate, but hot peppers and coriander (or cilantro) can take weeks to sprout the first leaves.

Before you abandon the pot, make sure your expectations are realistic. Do not expect habanero or Ghut Jolokia ghost peppers to germinate in a few days.

If you believe something is wrong, pick and inspect a few seeds with a toothpick. If there are no signs of life, evaluate, learn, adjust, and plant new seeds. 

You can use the same potting soil again. Just start over and implement what you have learned.

7. What to do if you plant too many seeds

Were you too generous when you scattered seeds in your container? If so, chances are that you are now facing a forest of sprouting seedlings.

This is a happy problem, but it is still a problem you must address.

You want vigorous seedlings to develop into strong plants. Having too many seedlings in a small space will lead to competition for nutrients, light, water, and all other things a growing plant needs.

Sharp garden scissors make thinning seedlings easier
Sharp garden scissors are great for thinning seedlings

You must thin the seedlings to create adequate growing space for your most robust seedlings. 

You have three choices. 

  1. Transplant clumps of seedlings into new containers:
    This is not my recommendation, as you typically end up with smaller groups of still dense-growing seedlings.
  2. Prick out seedlings and move them into new pots:
    A good option, but it can be tricky to move fresh seedlings, and you risk tearing delicate root systems.
  3. Cutting weaker seedlings:
    Use sharp scissors to cut the weaker seedlings just above the soil level. This is the least intrusive method, as you do not risk disturbing the remaining seedlings’ root system.

8. What to do with tall, spindly, and leggy seedlings

Tall, gangly, leggy seedlings are less likely to develop into vigorous plants. And often, it is better to start over. 

But there are exceptions to the rule. 

Leggy tomato seedlings can be transplanted deeper and will grow fresh roots along the stem. 

Leggy basil seedlings can be propagated in water by taking cuttings and growing into new plants.

If you decide to keep your leggy seedlings, support them with string as best as you can, and ensure you give them plenty of natural light.

If you are using grow lights you need to double the time needed for your plants. 6-8 hours of natural sunlight means a minimum of 12 hours of artificial light.

Summary

When you have reached this step, you should have healthy-looking solid seedlings to transplant into pots, containers, or, why not, your garden.

Transplanting seedlings into larger pots is as simple as placing the entire plant with soil and root system into the new and larger pot. Ensure you water the plants before transplanting them and pre-moisten the soil in the receiving pot.

If you plan to transplant the seedlings outdoors, ensure you harden off the seedlings first. Expose the seedling to the outdoors for a couple of hours on the first day and then increase the time spent outdoors over a week or two. 

And needless to say, ensure you are frost-free, and the average soil temperature is above 10 degrees Celsius / 50 degrees Fahrenheit.

Best of luck; you got this!

If you liked this article, you might enjoy “Starting a vegetable garden? 15 tips I wish someone had told me“.

Meet the author: Mattias is an experienced gardener spending most of his free time on his knees among herbs, plants, and garden vegetables. For the past two years, he has been sharing gardening projects and how-to tutorials on the NordicLavender website and YouTube channel.