Wednesday, March 17, 2021

Get Growing this spring: a guide to indoor seeding

By: Candice Keast

As spring approaches, gardeners are often faced with one big question: do we start our garden in May with seedlings purchased at our local garden centre OR do we get ahead of the game and grow from seed? Of course, you can do a combination of the two - choose whatever is right for you!

Seedlings growing in an egg carton.

I'm on the indoor seeding train because it allows me to put on my gardening hat earlier in the year. I start indoor seeding in March and early April, then when the weather warms up, outdoor seed in late April and May. Growing from seed is inexpensive and fun but can be challenging. Are you up for a challenge?

Read more to learn about:

In Canada, we have a short growing season (May – October), so think of indoor seeding as a way to get ahead of the growing season. For plants like tomatoes and peppers, warm temperatures are crucial for germination. Starting crops indoors ensures that they will reach maturity before the growing season finishes and allows for a few early harvests.

Here are a few examples of veggies and herbs you can start seeding indoors and are great for containers: 

  • Eggplant 
  • Tomatoes 
  • Peppers 
  • Mouse melon
  • Cucumbers
  • Zucchini 
  • Swiss chard
  • Watermelon
  • Squash
  • Pumpkin
  • Basil 
  • Parsley 

Tip: Some of these plants come in compact varieties, which is helpful if you think tomatoes or pepper plants for example will get too big for your space. I have a tiny balcony so, to maximize my space and grow more food, I opt for compact plants such as Tiny Tim Cherry Tomato and Doe Hill Golden Sweet Pepper. These are both pictured below and grown from seed!

Tiny Tim Cherry Tomato plant and Doe Hill Sweet Pepper plant fully mature in separate containers on a balcony.
L: Tiny Tim Cherry Tomato, R: Doe Hill Golden Sweet Pepper

For planting times, it's best to follow the instructions on the seed package as start times vary. You can purchase seeds online or from your local hardware store, garden centre/plant nursery or sometimes even your grocery store. I recommend using organic seeds, which you can find lots of options online by searching "organic seeds Toronto".  

Check out these helpful resources: 

What You'll Need

Aside from seeds, growing indoors requires the same things you need to grow outdoors: containers, soil, warmth, water, light, and airflow!



Good news! You can start seeds in just about any container you have lying around. Better yet, use something that you'd throw out, recycle or even compost! I've reused an old plug tray, newspaper pots, toilet paper rolls, egg cartons, and eggshells.  You can also use plastic food containers such as yogurt or sour cream containers. Poke a few holes in the bottom to avoid waterlogging.


Whatever container you decide to use, make sure you have some sort of clear covering like a plastic lid or cling wrap. This will keep soil from drying out too quickly. Moisture is essential for seed germination. When you see about 50% of your sprouts come through, remove the cover altogether. 

Here are a few container options:

Four different zero-waste containers: newspaper pots, toilet paper rolls, egg shells, and an egg carton.
Photo credit: Candice Keast

Tomato seedlings growing in toilet paper rolls.
Photo credit: Kim Stemshorn

Seedlings growing in plastic yogurt containers.
Photo credit: Annemarie Baynton


The soil you use for indoor seeding should be light, fluffy, and sterile. Light and fluffy soil will allow for just enough moisture and sterile soil will prevent disease. Regular garden soil is too heavy, so the delicate roots won't be able to push through. Use seed starting soil for best results.


Once your seeds have sprouted and the seedlings are a bit more mature, you can add some compost. Try sprinkling in a little vermicompost. Vermicompost, AKA worm poop, worm castings or vermicast, is the by-product of an indoor worm composter. Worm castings are an excellent organic fertilizer or soil amendment. My good friend and colleague Kim gave me a jar of vermicast from one of her many indoor worm composters! If you don't have a friend like Kim, you can find worm castings online or in your local garden centre.



To support your seeds through germination, ensure they are kept in a relatively warm spot away from any draughts. You want the area to be warm but not too hot. Some seeds like peppers and tomatoes need to be warm to germinate. If you are using heating pads to germinate your seeds, remember to remove the heat as soon as the seeds sprout.



Water, but try not to overwater. Ensure the soil stays evenly moist and avoid drenching your container. Overwatering is a sure-fire way to kill your little sprouts and seedlings. Use a spray bottle or a turkey baster to water your seeds. Using a watering can may be too forceful and dislodge your freshly sown seeds.



Before germination, you won't need any light because the seeds will be under the soil. You can keep them away from the window at this time. Once your babies sprout through the soil, take off the covering and place them in a sunny window. However, I would strongly consider investing in a LED grow light. Lighting is very critical at the growing stage; in fact, seedlings require a minimum of 16 hours of light/day. Without a good light source, your seedlings could wind up spindly and feeble. Another bonus is that grow lights can be connected to timers, so that you can program 16+ hours of light each day. Keep your grow light about 3-4 inches above seedlings. 


 Air flow 

Your seedlings will also benefit from moving air. You can run a small oscillating fan, directed at the plants to help build thicker stems. You'll be happy with the sturdy stems when it's time to transplant into the garden bed or balcony container. If you can't set up a fan you can also run your hand along the tops of the seedlings to strengthen the stems. Do this every time you water to mimic the movement of air.


Sowing Seeds: Step-by-Step

  1. Fill your containers with soil.
  2. Use your fingertip to make a slight depression in the soil. If you are planting tiny seeds, pinch 2 to 5 seeds per container. If you are planting large seeds, sow one seed per container and plant the seed deeper. When in doubt, follow the sowing instructions on the seed package. 
  3. Gently cover your seeds with a little soil.
  4. Water! Again, remember to moisten the soil evenly – don't overwater! Use a spray bottle if you have one.
  5. Label your containers with what you're growing and the date. It's easy to forget what you planted and when.
  6. Cover your container with a plastic or clear cover and poke a few toothpick-sized holes in the cover for ventilation. 
  7. Remove covering and move to a sunny window or turn on your grow light when 50% of sprouts appear. 

Here are the things you'll want to keep an eye out for: 

  • Ensure soil remains evenly moist 
  • Check on their growth and raise grow light to keep that 3-4 inch gap 
  • If you're not using a grow light, turn your seedlings often, so they don't bend toward the light 
  • Transfer seedlings to slightly bigger containers e.g. 4 or 6 inch pots when they outgrow the container they are in.

If this is the first time you are trying indoor seeding, don't take on too much. Choose one or two crops you'd like to try growing indoors. Then, when the ground can be worked, try sowing a few outside (direct sowing), and after the last frost, plant the rest of your garden using seedlings.

Feel free to ask questions in the comment section below & be sure to share your progress with us on social media by tagging @LiveGreenTO and using the hashtag #GetGrowing.


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