How to Repot Tomato Seedlings

Repotting seedlings in general is fairly straightforward. Just plop the plant out, put it in a new container, and refill with soil.

But tomato seedlings are unique in that they like to be buried deeply. They have the ability to form new roots along their stems, so they can be repotted up to their lowest set of leaves. A bigger root system means a healthier and more robust plant.

Tomato seedlings are ready to be repotted when they are at least 3 inches tall, and have a couple sets of “true leaves,” the second and subsequent sets of leaves that appear. The first leaves that sprout, cotyledons, are not leaves at all, but embryonic structures from the seed that provide nutrition until the seedling can make its own food.

Repot seedlings after true leaves appear

Start with clean 4-inch pots and pre-moistened sterile potting mix. If several seedlings are growing in the same pot, some people will snip off the extras and keep only the strongest seedling, so as not to disturb the roots during transplant. But if you repot them before they become rootbound, it’s quite easy to separate the seedlings without damaging the roots.

Start with clean pots and sterile potting mix

Water your seedlings to loosen up the potting mix and keep the roots moist while you work. If you started your seedlings in newspaper pots, unroll them. The roots should be fairly developed and free.

Unroll newspaper pots

Roots from tomato seedlings

Separate the seedlings. Always handle them by their leaves, not their delicate stems. If a leaf pulls off, chances are it will grow back. But if the stem snaps, your seedling is done.

Handle seedlings by their leaves

Separate the seedling by gently pulling on its leaves and wiggling it away from the potting mix. The roots should release easily. Let the moist potting mix cling to the roots to protect them from drying out.

Let moist potting mix cling to the roots

Fill the new pot with fresh potting mix, and sink in the seedling to its lowest set of leaves. Pat down the mix gently and water.

Fill pot with fresh potting mix

Plant seedling up to its lowest set of leaves

Keep your newly repotted seedlings out of direct sunlight for a day or two. Tomato plants are especially susceptible to overwatering, so keep the potting mix barely moist at all times. Water deeply to reach the roots at the bottom (or soak from the bottom up), and only water again when the first inch of the mix feels dry.

Tomato plants can be repotted two or three times before they go in the garden. Moving them into larger containers each time keeps them happy and gives their roots room to grow. If you are repotting a second time, you should pinch off the bottom two or four branches and sink the plant even more deeply into the pot to encourage new root growth along the stem.

Repotted tomato seedlings

And all that recycled newspaper you unraveled? You can recycle them one more time by adding them to your compost!

Recycled newspapers can be recycled again

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April 7 2011      22 comments     Linda Ly
Jardín   Verduras

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  • Julia

    Ian- It only sounds “fiddly” if you’ve never raised and planted tomatoes before… it’s simply how it’s done. If you skipped transplanting them, you’d have weak, worthless plants on your hands. If ever you buy tomato seedlings from a garden center, you want short and stalky plants… never tall and spindly. The shorter ones are healthier and have the strong root systems you want, which occurs when you transplant your seedlings in the manner described. You also want to plant them to within an inch of their lowest leaves when you put them in their permanent homes in the ground or in large containers outside, too–they will continue growing stronger and stronger roots if planted that way. (FYI- my tomatoes were the healthiest ever last year… no black-winged aphids at all, and all I did differently was interplant basil with them and use old coffee grounds as a fertilizer.)

    Cheers, and happy gardening!

    • http://handycrowd.com/ Ian Anderson

      Companion planting is clever stuff isn’t it? This is the stuff that our grandfathers took for granted. Seems like the old ways are still the best when it comes to gardening. Nothing like the pressure of actually going hungry to motivate you to get it right eh?
      Re the toms, yes I see that now, now I know why I felt like I ran out of time with my first toms last year. Weak roots that took way too long to get established.
      You’ve saved the day here :-)
      Thanks!

  • http://handycrowd.com/ Ian Anderson

    Hi Betty,
    I’m curious though. What would happen if you simply planted the seeds in the end pots (biggest) to start with? Or is it the repeated deepening when repotting that boosts the root system?

    I might try a comparison next year! I guess I just find it a bit fiddly re-potting all the time. Big fingers and small seedlings huh!

    Thanks for the info about planting deep, didn’t know that!
    Stay well

    • http://www.gardenbetty.com/ Linda Ly

      The reason for re-potting is to keep burying the stems deeper each time, and thereby encouraging more roots to develop along the part of the stem that’s underground. Planting your tomatoes in a gallon pot initially would make no difference than if you were to plant them in a smaller pot, other than giving you more time to plant them outside before they get rootbound.

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  • http://pulse.yahoo.com/_YNGMSOZBPUXE23J2P2GBLJOFRU Eve

    I have to tomato seedlings in one pot. I’m planning to remove the smaller one to the other pot so they can both survive. What is the best way to separate them from one another? My friend told me to take the soil ball and irrigate it until the soil disappear. Then untangle them gently. I’m planning to do it on my tomatoes but can I also use that procedure to my new Marigolds? Thanks!

    • http://www.gardenbetty.com/ Linda Ly

      I just gently pull the roots apart with my hands; never had a problem with any of my seedlings this way.

  • oukay

    I found that I would put off the transplanting too long if I put them in new pots.  so now I start my tomatoes in cups or 4″ pots with just a couple of inches of soil.  Then as they get larger I start adding soil to progressively cover the stem.  This works well for me.

    • http://www.gardenbetty.com/ Linda Ly

      Clever! I use that method for growing leeks, too.

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  • Denise

    I started some of my tomatoes in eggshells- can I just bury the shell in the potting soil or should I try to get the plant out?

    • http://www.gardenbetty.com/ Linda Ly

      Just crack the eggshell slightly to allow the roots room to move around, and plant in the ground as-is. Tomatoes love the added calcium from eggshells.

  • http://www.gardenbetty.com/ Linda Ly

    Very interesting viewpoint. I have always waited until the true leaves appeared before transplanting. This way the seedlings can draw more energy from a larger source than the cotyledons, thus increasing their chances of survival. All my plants have done well this way. But I agree that the sooner and smaller the plant, the better.

  • http://twitter.com/kctomato KC Tomato

    I’d recommend transplanting them at an earlier stage. About a week or 10 days before the ones shown. An earlier stage reduces transplant shock which slows growth and could effect primordial floral development.

    The earlier stage will look like the seedling “A” in this picture:
    http://kdcomm.net/~tomato/graphics/seedling.jpg

     

  • Hebron Acres

    Love the post.  For seed germination, we use the cores to toilet paper rolls and cut them in half and get two from each core.  Works great and, as you point out, excellent for compost once plants are transplanted.

  • AshleyWaterstradt

    Thank you so much for all of this great information! This is my first time growing from seeds, and I’m loving all of your posts. :) 

    • http://www.gardenbetty.com/ Linda Ly

      The joy for me is just in seeing those little seeds sprout! Have fun this season!

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  • http://www.garden-furniture-outlet.co.uk/wooden-garden-furniture Wooden Garden Furniture

    Thanks for sharing the knowledge about repot of tomato seeding. This knowledge helps me so much in future.
    I am here for first time and likes the blog entries in this blog.I will glad to follow this blog in future

    With regards
    Shaun…….

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