Starting Tomato Seeds Indoors – 5 Tips to Help Ensure Success

By | March 13, 2014

Starting Tomato Seeds Indoors - 5 Tips to Help Ensure Success #gardeningAlthough 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 tomatoes and bell peppers. So today I thought I would share 5 tips for starting tomato seeds indoors.

 Pre-germinate your seeds.

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 pre-germinate my seeds before I plant them in the soil.

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

To pre-germinate your seeds you will need a zip close sandwich baggie and a coffee filter (I use unbleached coffee filters).  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, then fold it in half and then in half again.  Put the folded coffee filter into the sandwich bag and close.  Place 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.    My tomato seeds germinated in 4 days using this method!  Once you have roots, you can go ahead and put the seeds into soil – 1 per pot since you know it already germinated.

Start with only an inch of soil in the pot when you plant the seed.

This may sound odd, but tomatoes are one of the few plants that will grow roots all along the stem if you bury it.  So what I do is add more soil to the pot as the seedling grows.

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

Every couple of days, I add more potting soil to just below the leaves.  I keep doing this until I reach the top of my pot.   This process ensures you have a strong healthy root system.

Maximize light to your seedlings.

If you are lucky enough to be able to start tomato seeds indoors under a fancy light set up, I envy you!  I unfortunately don’t have a lot of extra room so I have to rely on the light coming in from south facing windows.  One thing I do is to help maximize the light reaching my seedlings is to use a small piece of foil to cover the top of the cup, leaving a hole for the stem of course.  This will help bounce light to the undersides of the leaves.  If you are using window light, be sure to turn your seedlings daily because they will lean towards the light as it grows.

Have a fan blowing on your seedlings.

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.  What I like to do is have an oscillating fan blowing on the seedlings for about a half an hour each day.  This helps them develop stronger stems.  A tabletop oscillating fan is inexpensive and works great for this.

Prevent 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 avoid it.

  • You want to keep the soil damp, but not sopping wet. Excessive moisture can increase the risk of damping off.
  • Have adequate air circulation.  The fan I mentioned above will help with that.
  • Sprinkle some cinnamon on top of your soil.  It is anti-fungal and can discourage the growth of organisms that cause damping off.

Hardening off your tomato plants

Once the weather has warmed and it’s time to plant your tomatoes outside, you will want to gradually get your plants used to being out in the elements.

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

Too much sunlight or wind all at once can be a huge shock to your plants who were used to a posh life indoors.   I usually start with putting my plants in a shady location and then gradually move them so they get more and more sunlight each day.  It takes about a week to harden your plants so they will be ready to plant in your vegetable garden.

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

13 thoughts on “Starting Tomato Seeds Indoors – 5 Tips to Help Ensure Success

  1. Katie

    So you’re skipping seed starting mix altogether and putting them into potting mix on the 4th day once they have germinated? This is my first attempt at starting tomato seeds, so I don’t know what I’m doing!

    1. Jen

      Hi Katie,
      I never use seed starting mix. I use potting mix that has plant food in it. Let me know if you have any other questions.

      1. Katie

        So do you plant them as soon as they have germinated at day 4 in your case?

        1. Jen

          Yes, as soon as you see a root coming from the seed, you can plant it. It doesn’t need to be very deep. I just lightly cover it with soil and make sure to keep the soil moist.

  2. Priya

    Could you tell me how you add potting soil to the pot as plant grows without disturbing the plant itself?

  3. Lisa W

    Hi there,

    I enjoyed reading this. I really appreciate the part about not wasting seeds. It pains me to pull the extra little ones. Now I will do it your way and not have to do away with any of the baby tomato seedlings! :0) This is very informative and I would like to share this on my Facebook Page with a link back to your website if you don’t mind.

    1. Jennifer Post author

      I am glad you found the information useful. Feel free to share the link to this post on your Facebook page. Thanks for visiting!

    1. Jennifer Post author

      Thanks for visiting Linda! You definitely want to harden your plants off. Before I learned to do that, I gave many of my tomato plants sunburn because they couldn’t handle it for long periods of time at first.

  4. AnneMarie

    Jennifer, this is really cool! I tend to fail miserably at anything gardening-related (I tried growing basil and arugula last year…things started to sprout, but then died), but I would love to attempt tomatoes someday, since I love tomatoes and homegrown are so much better than those at the store! Unfortunately, we don’t get a huge amount of direct sunlight on our apartment’s porch, so I may have to wait on this project for when we eventually get a house with (hopefully) a sunny place to grow things 🙂

  5. Diana Rambles

    Great tips! Congratulations! This post is going to be featured over at Diana Rambles tomorrow and has been pinned in the Featured at Diana Rambles board at Pinterest and Tweeted. Please grab a featured button off my button page or via the post guidelines graphic. Thanks for sharing this awesome idea!

  6. Lenore

    Thank you for all the great tips. I am going to try this method this year!


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