A tomato gets moved more than almost any other plant you grow. It starts life in a tiny seed cell and gets bumped up into a roomier pot as it grows. Finally it goes out to the garden or a big container. Each move is a chance to make the plant stronger, or to set it back if you rush it.
Transplanting is just the art of moving a tomato without knocking the wind out of it. Do it right and the plant barely notices, and often surges ahead. Do it wrong and you get a droopy, sulking seedling that takes a week to bounce back. This guide covers the whole thing. When to pot up, how to do it without hurting the roots, when the plant is ready to head outside, and how to dodge transplant shock.
The two moves every tomato makes
It helps to keep the journey straight in your head, because “transplanting” covers two different steps.
The first is potting up. If you started your tomatoes from seed, they’ll outgrow their little cells long before it’s warm enough to plant outside. So you move them into bigger pots to keep them growing strong indoors. This can happen once or even twice before planting day.
The second is planting out, moving the hardened off plant to its final home in the garden or a large container. That final step has its own guide, since there’s a lot to get right on planting day. This article is mostly about the first move, potting up, plus the shock that can hit at any transplant. For the outdoor step, head to our full guide on how to plant tomatoes.
When to pot up tomato seedlings
Timing the first move is easy once you know the signal to watch for. It’s the true leaves.
When a tomato seedling first sprouts, it opens two smooth, rounded leaves. Those are the seed leaves, and they don’t look like tomato foliage at all. The next leaves to appear, the jagged ones that actually look like a tomato plant, are the true leaves. Once a seedling has its first set or two of true leaves, and the roots are filling the little cell, it’s ready. Time to move up to a bigger pot.
Don’t leave them cramped for too long. A seedling stuck in a tiny cell gets root bound, its roots circling in a tight knot with nowhere to go. Growth stalls. Moving it into fresh, roomy soil gives the roots somewhere to run and keeps the plant climbing. If you started your own seeds, our seed starting guide walks through everything up to this point.
How to pot up a seedling, step by step
Potting up takes about a minute per plant once you’ve got the hang of it. Here’s the routine.
Get your bigger pots ready first, something like a 3 or 4 inch container, filled partway with fresh potting mix. Water the seedlings an hour or so beforehand, since a moist rootball holds together and slides out cleanly.
Now ease the seedling out. Don’t yank it up by the stem, which bruises easily. Instead, push up from the bottom of the cell or tip the pot and let the plant slide into your hand, cradling the rootball. The whole trick here is to keep that rootball intact. The less you disturb the roots, the less the plant even notices the move.
Here’s the tomato bonus. Just like planting out, you bury a tomato deeper each time you pot it up. Set the seedling low in the new pot. Fill in around it so the soil comes up to just below the lowest leaves, burying a good length of stem. That buried stem sprouts new roots along its length, so every potting up builds a bigger root system. Firm the soil gently, water it in, and you’re done.
If a seedling has gotten tall and leggy, this is your chance to fix it. Bury even more of that long stem, right up to the top leaves, and the plant comes out sturdier than it went in.
When to transplant tomatoes outside
The final move, out to the garden, is all about the weather. Tomatoes are warm weather plants that can’t take cold, so you wait for a few things to line up.
Wait until all danger of frost is well past, the soil has warmed to at least 60 degrees, and nighttime temperatures are steadily above 50. Utah State University Extension sets that soil mark at 60 degrees, and warmer is better. Cold soil and chilly nights just stall a tomato. A plant set out too early gets overtaken by one planted a couple of weeks later into warm ground. Patience pays here.
And before that outdoor move, you have to harden the plants off. That means easing them into sun, wind, and cooler air over a week to ten days so the shift doesn’t shock them. The exact day by day schedule is in our hardening off guide. The full timing and planting depth for this step live in our planting guide.
Transplant shock, and how to beat it
Here’s the part everyone worries about. Transplant shock is the setback a plant suffers when its roots get disturbed and its surroundings suddenly change. The classic sign is a seedling that wilts, droops, or looks sad for a few days right after a move.
The good news is that a little droop is normal and usually passes on its own. The plant is just catching its breath while the roots settle in. Real trouble only shows up when the roots got badly damaged or the plant was moved at the wrong time.
The cause is almost always the roots. Plants weren’t designed to be moved. Any time you disturb the roots, you risk a little shock, no matter how careful your hands are. That single fact points straight at how to prevent it.
To keep transplant shock to a minimum:
- Keep the rootball intact. Don’t shake the soil off or rough up the roots. Move the whole moist ball of roots and soil together, and the plant hardly notices.
- Water before and after. A drink an hour before the move keeps the rootball together, and a deep soak right after settles the soil and rehydrates the roots.
- Move at the right moment. For the outdoor step, plant on a cool, cloudy day or in the late afternoon rather than in blazing midday sun. The plant gets to settle before it faces full heat.
- Don’t skip hardening off. A soft indoor plant dropped straight into the garden is the number one cause of a bad outdoor transplant. Ease it outside first.
- Handle by the leaves, not the stem. If you do bruise a seedling, a crushed leaf recovers, a crushed stem may not.
Do those and most of your tomatoes will shrug off each move without missing a beat.
Helping a shocked plant recover
Say you’ve got a tomato that’s wilting and sulking after a transplant. What now?
Mostly, patience. Give it a deep watering and keep the soil evenly moist but not soggy. Put it somewhere out of harsh, direct sun for a day or two while it recovers. Resist the urge to pile on fertilizer, since feeding a stressed plant with damaged roots does more harm than good. Water and time are the real cure.
Give it a few days. A tomato is a tough, forgiving plant, and the vast majority bounce right back and carry on growing. If a plant is still struggling well after that, the trouble is usually something else. Our tomato plant problems guide can help you track it down.
Frequently asked questions
When should I transplant tomato seedlings?
Pot them up into bigger containers once they have their first set or two of true leaves and the roots are filling the cell. Move them outdoors only after all frost has passed, the soil is above 60 degrees, and nights stay above 50. Harden them off first.
How do you transplant tomatoes without shock?
Keep the rootball intact, water before and after the move, and plant deep. For the outdoor move, harden the plants off first and transplant on a cool or cloudy day. Most shock comes from disturbed roots or moving too early.
Should I bury tomato seedlings deeper when I pot them up?
Yes. Tomatoes grow new roots along any buried stem. Each time you pot up, set the plant lower and bury more of the stem, up to just below the lowest leaves. It builds a bigger, stronger root system and fixes leggy seedlings.
Why is my tomato seedling wilting after transplanting?
Usually mild transplant shock as the roots settle in, which passes in a few days with a good watering and some shade. If it lingers, the roots may have been damaged in the move, or the plant went out into cold soil too early.
How long does transplant shock last in tomatoes?
Often just a couple of days for a healthy plant that was moved carefully. Give it steady moisture and a little shade and it should perk back up. A longer struggle points to root damage or bad timing rather than simple shock.
Bottom line: move your tomatoes up as they outgrow their pots, keeping the rootball intact. Bury the stem a little deeper each time, and water them in well. Wait for warm weather and harden them off before the final move outside. Handle the roots gently and transplant shock stays minor. From here, our guides to getting them in the ground and the full growing guide take you the rest of the way.