Starting Tomato Seeds Indoors in the Winter – 5 Tips to Help Ensure Success

Starting tomato seeds indoors in the winter - it's easier than you think! Here are five great tips to help ensure your success!
Starting tomato seeds indoors in the winter – it’s easier than you think! Keep reading to learn five great tips to help ensure your success!

Although it is currently only 30 degrees and snowing outside, I am already dreaming of the yummy vegetables I am going to be growing in my garden this summer. Most of my seeds are started using the winter sowing method, but a few things I start inside – mainly heat lovers like tomatoes and bell peppers. So today I thought I would share 5 tips for starting tomatoes seeds indoors.

Success with starting tomato seeds indoors in the winter involves 5 things:

  • get your seeds to germinate
  • develop a strong root system
  • prevent damping off
  • give your plants as much light as possible
  • develop sturdy stems

But how do you do those things?  The tips below will ensure that you grow strong, sturdy plants that will produce lots of yummy juicy tomatoes for you this summer.

1.  Coffee filter seed germination

I know a lot of gardening gurus recommend planting 2-3 seeds in each pot, but I think that is wasteful.  Why use multiple seeds, only to have to get rid of perfectly healthy seedlings?  My solution is to use the coffee filter seed germination method.  I pre-germinate all my seeds before I plant them in the soil.  That way I know the seeds are viable and it greatly reduces waste.

Germinating tomato seeds on paper towels means less time thinning out seedlings and less seed waste. Learn more here!

To use the coffee filter seed germination method,  you will need a zip close sandwich baggie, a coffee filter (I use unbleached coffee filters), and water.    If you don’t have any coffee filters, germinating tomato seeds on paper towels also works.  The method is the same whether you use paper towels or coffee filters.  I prefer the coffee filters though because they are a little more sturdy when wet.

Melitta 8-12 Cup Basket Filter Paper (Natural Brown, 200 Count)Melitta 8-12 Cup Basket Filter Paper (Natural Brown, 200 Count)

Start by thoroughly wetting your coffee filter with warm water and then wring it out.  You want it damp, but not dripping.  Place as many seeds as you want on the filter.  If the seeds are fresh (labeled as packaged for the current year), use 2-3 more seeds than plants you want in the end, in case a few don’t germinate.  If the seeds are older, be a little more generous with the amount you use.

Fold the damp coffee filter with your seeds in half and then in half again.  Put the folded coffee filter into the sandwich bag and close.  Place the baggie in a warm spot (like on top of your fridge) and check every couple of days for roots emerging from the seeds.  Be sure that the coffee filter doesn’t dry out.    If it is starting to get dry, use a spray bottle filled with water to lightly mist the coffee filter, then close the bag back up.

Tomato seed germination time using this method is typically 4-5 days. (f course this depends on how old the seeds are, how warm your home is, etc.


Once the roots emerge from the seeds, you can go ahead and put the seeds into soil.  You only need 1 per pot since you know the seed has already germinated.

2. Encourage a healthy root system by adding more soil as the plant grows.

This may sound odd, but tomatoes are one of the few plants that will grow roots all along the stem if you bury it deep.  You can encourage this process by adding add more soil to the pot as the seedling grows.  So put that just germinated seed into a pot that has about an inch of potting mix and then lightly cover it with little bit more potting mix.

Starting Tomato Seeds Indoors - 5 Tips to Help Ensure Success #gardening

Let the plant grow until it has developed the first set of true leaves, then add more potting soil to just below the leaves.  As the plant grows, continue this process until your pot is full to the top with soil.  This process ensures you will have a strong healthy root system.

When you transplant into bigger pots, remove the lower sets of leaves and make sure the spots where you removed the leaves are buried beneath soil. More roots will develop from the spots where you removed leaves.

A bigger root system = a stronger plant!  So we want to do all we can to encourage the tomato plants to develop a vigorous root system.

3. Prevent Seedlings Damping Off

Nothing is more frustrating than when a healthy seedling suddenly keels over and dies from the dreaded damping off disease.  It’s not 100% preventable, but there are some steps you can take to help prevent seedlings damping off.

  • You want to keep the soil damp, but not sopping wet. Excessive moisture can increase the risk of damping off.  Allow the top of the soil to dry between waterings.
  • Have adequate air circulation.  More on that in step 5.
  • Water your seedlings with a dilute chamomile tea solution.  I use diluted chamomile tea to water my all my seedlings until their second set of true leaves appear.
  • Sprinkle some cinnamon on top of your soil.  It is anti-fungal and can discourage the growth of organisms that cause damping off.

I water with chamomile tea and let the soil surface dry out between waterings.  Using those methods, I am able to prevent seedlings damping off about 95% of the time.

4. Maximize light to your seedlings.

Plenty of light is essential for starting tomato seeds indoors in the winter.  You can either use a seed starting light setup or south facing windows.

Plenty of light is essential to start tomatoes seeds indoors in the winter. You can either use a seed starting light setup or south facing windows. Learn more here.

Light setups for seed starting don’t have to be expensive.  I use a metal shelf system with inexpensive florescent shop lights.  I keep the lights about 2-3 inches from the top of the plants and use the chains to move them upward as the plant grows.

In our first house, I didn’t have room for a light set up, so I had to rely on south facing windows.  The plants grew just fine in the window.   I just made sure I turned the plants periodically because they tend to grow toward the light.

5 tomato seed starting tips that will ensure strong sturdy plants. Read all about them here!

If you are relying on a window to provide light, one thing you can do to help maximize the light reaching your tomato plants is to use a small piece of foil to cover the top of the cup, leaving a hole for the stem of course.

The foil will help bounce light to the undersides of the leaves.  And more light is always a good thing for plant growth!

5. Have a fan blowing on your seedlings.

Oscillating Clip FanOscillating Clip Fan

Tomato seedlings grown indoors have a pretty comfy life!  Unfortunately that can leave your plants with weak stems because they have never been exposed to wind.

One thing you can to to help your tomato plants develop thicker stronger stems is to have an oscillating fan blowing on the seedlings for about a half an hour each day.  A tabletop oscillating fan is inexpensive and works great for this. I like the ones with the clips that you can attach right to the shelf holding your plants.


Hardening off tomato plants

Once the weather has warmed and it’s time to move them outside, you will want to gradually get your tomato plants used to being out in the elements.  Hardening off tomato plants will give your plants time to get used to the harsher conditions – like wind and the brighter light of the sun.

Hardening off tomato plants ensures that your plants don't go into shock when introduced to the harsh sun and wind of the outdoors.  Learn how here!

Too much sunlight or wind all at once can be a huge shock to your plants who were used to a posh life indoors.  You can start hardening off tomato plants by putting them outside in a shady location for a couple of hours.  Each subsequent day, gradually move them so they get more and more sunlight.  It takes about a week to harden your tomato plants so they will be ready to plant in your vegetable garden.

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Starting tomato seeds indoors in the winter - it's easier than you think! Here are five great tips to help ensure your success!

So tell me… Do you have any tips for starting tomato seeds indoors in the winter?  Be sure to share your tips and tricks by leaving a comment below.


2 thoughts on “Starting Tomato Seeds Indoors in the Winter – 5 Tips to Help Ensure Success

  1. Vanessa


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