Garden Duties: Starting Seeds Indoors
Updated: Jul 30
As a gardener, this time of year can make one antsy. We have seeds ordered and counted, plans are drawn up and we are watching out the window until the snow melts and the ground warms up... Okay maybe not watching but definitely waiting. Up here in Canada, winters can seem like a white blanket of cold days and endless layers of clothes. Waiting for it to be over can seem like an endless torture as our green thumbs begins to tap constantly like your annoying uncles leg underneath the dinning room table.
To our relief, there is a way to get a jump start on the gardening season. One word: SEEDLINGS. Sowing seeds indoors allows you to get a jump on the growing season. Though let's hold the fort here, some seeds aren't best grown as transplants and are advised to be sown directly into the ground. Those able to be grown for transplants are started early so you'll have strong, vigorous seedlings ready to go into the ground once the regular growing season begins. In areas with short growing seasons, this method is ideal.
Equipment Needed To Start Your Seeds Indoors
Growing or Flat Trays
What is a Growing Tray?
This is a product that I wouldn't skimp out on. A flat tray is designed to hold a 10x20 seedling tray or individual seedling cells. This tray is ideal to use as a drip tray, pouring the water into the bottom to be absorbed up through the soil cells.
Plastic Tray - no holes, used to hold seedling trays or cells.
Plastic Tray - with holes, used for growing micro greens directly into the flat trays.
PROTIP: I advise getting ones that are extra thick and don't bend when you pick them up.
This allows you to reuse them year after year without any of them tearing or breaking. I have learned that lesson the hard way before.
Seedling Germination Trays or Cells
What is a Germination Tray?
A seed starting tray is exactly what it sounds like - a plastic tray with multiple small cells designed to hold seedlings. There are a couple different ones you can use.
- Germination trays or plug trays are made of a rigid plastic and allow you to plant one seed per cell to grow individual seedlings, making it easier to transplant. They come in 50, 72, 128 and 200 cells.
- Soft cell packs, 6 pack. Not always as sturdy as the plug trays but great for anyone who needs to start seedlings. You can place 2 to 3 seeds per cell pack. It does make it a little more intimidating to transplant as you have to separate them without damaging too much of the roots.
What is Soilless Mix?
In plain-speak, soilless mix has a light texture, fewer nutrients, and is sterilized. Most mixes are comprised of:
- Sphagnum peat moss, which is slightly acidic that provides well-draining and water retention.
- Bark, which improves drainage and airspace.
- Coir, a coconut fibre by-product that works similarity to peat moss.
- Perlite, a volcanic mineral, also helps with drainage and air and water retention.
- Vermiculite, is a silicate material that has been heated and expanded to increase its water holding capacity. They soak up water and nutrients until the plants need them.
Can you tell what they all have in common? Wetting agents have become increasingly popular to allow for superior drainage.
Why use a Soilless Mix?
- Special sowing mix has fewer nutrients to make sure the young roots develop well-branched and a vigorous root system.
- Seeds will need an environment with a steady water supply without waterlogged conditions, which it can provide.
- Soilless mix provides a cleaner medium and allows more control over the surrounding environment from pests, disease and other contaminants.
What is a Heat Mat?
Basically, it is a sheet of plastic that has heating elements embedded inside. When plugged in, the elements heat up anything that is sitting on it. The seed mat I own raises the temperature of the soil by about 6-11°C warmer than the ambient temperature. The heat is subtle, but constant.
Why use a Heat Mat?
Here in Canada it gets really cold, even in the house. Though we have some heat elements turned on, base board or a heat pump, that doesn't mean your growing area will provide adequate warmth for the seeds.
For example: Peppers are a warm season crop, the soil temperature ranges for seed germination:
The minimum is 15°C
The max is 35°C
The optimal range is between 18-35°C
For BEST growth 21-24°C with a minimum of 18°C
For example: Cole Crops are well adapted to cool season production, the soil temperature ranges for seed germination:
The minimum is 5°C
The max is 37°C
The optimal range is between 7-27°C
For BEST growth 27°C
Once the seedlings begin to germinate, the heat mat can removed to slow down the growth and keep the seedlings stout and healthy.
If you are growing a lot of vegetables it's ideal to get yourself some labels whether they may be popsicle sticks or plastic sticks, ones where you can use a permanent marker or paint marker.
You may think that you will remember what is sown in each cell or pot, but many crops look very similar when they start to grow. It's hard to label each cell when you have a dome lid on top of the seed trays, so my best advice is to draw a diagram of what each seed tray is filled with. When the time comes, that they don't need the dome anymore, place a label at the end of each row to help indicate them.
When it comes to which one is better, I have used both and honestly people give popsicle sticks a bad rep. The truth is you only really need the labels when the plants are young or when they are transplants. Yes, popsicle sticks may fade down the road and no longer bare the permanent marker markings but honestly when the plants start to bare fruit or are tall enough to show their true colours does that really matter anymore? To me, no, because that means that I should know what it is by then, so don't discount them write away. I'd rather have faded food sticks out in the world than plastic sticks ANY day. On the other hand, plastic is durable and can be used for multiple years. No real secret to them, they work perfectly fine.
Why use a humidity dome?
They help protect the seeds by maintaining moisture levels, creating the perfect environment for a strong start.
Though the domes aren't necessary, using one will increase your germination rate and cut back on any heart ache when you notice some haven't sprouted. The amazing part about the dome is that you only need it until the first signs of germination. Once germination begins, remove the dome and start your trays under light with good air circulation.
How to prevent mold while using humidity domes
Mold on the surface of the soil can be caused by poor air circulation and prolonged recommended time of the dome being placed on top of the seedlings.
The best way to prevent any type of mold:
By using a dome that has adjustable vents.
By providing good air circulation and light from the start.
Planting seedlings that have similar germination times.
Cleaning trays and domes in between uses, giving a good rinse with a basic detergent.
The mold will often disappear once the tray has been exposed to proper airflow and light.
Why use a Grow Light?
When it comes to starting seeds indoor, in the middle of winter, a grow light can help your plants flourish where there is little of no natural light. Putting seeds up next to a window could create what is known as "leggy seedlings" which are tall and spindly, which may be due to insufficient light, high temperatures or even lack of moistures.
We know from science that plants need light for photosynthesis, the process within a plant that converts light, oxygen and water into energy (carbohydrates). To create similar properties as the sun, we use grow lights that uses a spectrum of light. Plants without adequate light, the energy aka carbohydrates cannot be produced, ultimately depleting any reserves and the plants die.
How to prevent damage to your seedlings
Scorching: Some lights can produce a lot of heat. If left too close to the tender seedlings, for a long period of time, it can scorch them. Fluorescent bulbs emit enough light while remaining cool, it is also advised to use the manufacturers recommended gap between the light and the plant.
Plant Growth: Make sure that once your seedlings start to grow so does the space between your plants and the light. This makes sure you are always receiving the same amount of light no matter the stage.
How long to use the light?
If you are familiar with the plants you are growing, you will know how much light the plants will need.
For example: Peppers need at least 6-8 hours of sunlight per day. You can always extend it slightly and aim for 10-12 hours of light each day. We also want to make sure that plants get up to 8 or more hours of darkness allow them to rest overnight, as they would out in the real world.
Spray Bottle and Watering Can
Watering is KEY to making sure you have a successful germination.
Guide to watering:
Keeping the soil consistently moist is your main goal when it comes to a seedling.
Don't Water from Above: it can flood and float the seed around in the cell, growing from the side of a cell might not make for a strong start. The water pouring out can also be quite abrasive to the tender seedlings, they are much healthier when dry and it helps avoid any soil born diseases.
Water from Below: fill the flat trays with water and allow the water to soak up through the soil from the bottom, working its way up to the top.
Use a Spray Bottle: spray the top of the soil with water to make sure it stays moist.
One thing you need to think about is: where exactly will you store these seedlings when you start them. Honestly, I keep them in a place where I go frequently, aka in my dinning room, because if they weren't close by you might not be as motivated to check on them or you even might forget about them.
An easy way to set up all you gear: heat mat, flat tray, plus trays, domes, lights, is on a storage shelve. An ideal storage shelve that seems to be perfect and hold 10x20 trays so easily is the kitchen storage shelves from Canadian Tire.
OKAY! Now let's plant.
How to Sow Seeds
1. Set Up Your Station
- Find the perfect spot in your house that doesn't have a lot of draft and somewhere you visit often. I placed mine beside my dinning room table on the main floor. There's no way I can miss it and I can check on it every morning and night.
- Make sure you have your shelving, heat mat, humidity domes, flat trays, seedling trays, lights and soilless mix.
- Take your heat mat and place it on the bottom of the rack and tie your lights up from the top of the rack (prepping for later).
- Grab all the seeds that you plan on planting that day.
- Grab your gardening book/computer spreadsheet/app, pens/markers and labels.
2. Map Out Your Seedling Trays and Labels
- Using your gardening book/computer/app trace out the tray and make a square for each cell.
- Write the name of each seedling on labels before planting.
- To make sure we don't get anything mixed up, as all four corners look the same, paint or place tape on one of the corners. That will allow you to keep the tray in the same position until you transplant them.
3. Prepare the Soilless Mix
- Grab a bowl and fill it with soilless mix.
- Add some water into the mix to moisten it up. Mix it evenly with your hands, make sure that it is soppy and not soak and wet.
- Fill each plug or cell with the pre-moistened soilless mix. One reason to pre-moisten the soilless mix is to avoid sinking issues. If you added the soilless mix dry, it technically isn't compact yet. Wetting it before-hand aids it from sinking down into the cell making giving the seedling less medium to grow in.
4. Sow Your Seeds
- Place the seedling trays on top of the flat trays.
- Most little seeds are planted 1/2 inch or an 1 inch deep into the soilless mix. Seed packs have instructions on the back of the packet, follow them.
- Place each seed in the cell you assigned it.
Plug tray - place one seed per cell.
6-pack cell - place 2-3 seeds per cell.
- I plant 2-3 of each type to ensure a good success rate.
5. Domes, Warmth, Water and Lights
- Humidity Dome: place dome on top of the plug tray once the seeds are sown. Once germination begins, remove the dome.
- Heat Mat: the mat is placed under the trays and turned on every morning until night. Once germinated, the mat is removed.
- Water from Below: fill the flat trays with water and allow the water to soak up through the soil from the bottom, working its way up to the top.
Never let the cell dry out completely in-between waterings.
Water at least twice a week, or three depending on the need.
- Use a Spray Bottle: spray the top of the soil with water to make sure the seedlings stays moist.
- Grow Light: seeds do not need light until they have begun germination. Make sure when using grow lights to keep it only a few inches above the plants. Once the seedlings start to grow so does the space between the plants and the light.
- Vegetable seedlings: need at least 12 hours of light per day, so make sure to turn them on first thing in the morning. They also need at least 8 hours of darkness as well. So make sure to turn off the grow lights at night.
All right, now that we have those seedlings started... how to Transplant. Coming soon!