Transplanting tomatoes: How to transplant tomato seedlings

Successfully transplanting tomato seedlings is vital for your tomatoes to develop a strong and healthy root system. And here, in this article, I will tell you all you need to know about transplanting all varieties of tomatoes.

The instructional video below shows me transplanting cherry tomatoes and Striped Stuffer beefsteak tomatoes. But this technique works for all varieties I have come across.

Follow my simple technique, and you will have success.

The Nordic Lavender way is to only write about topics where we have first hand experience. Our photos may not always be of professional studio quality. The reason is simply that we take our own photos from our own actual gardening projects. 

7 steps to transplanting tomato seedlings into pots

Watch this video on YouTube.
A proven method of transplanting tomato seedlings for plants with strong roots

1. Fill pot with soil 

Make a hole using your finger or an instrument but do not compact the soil

2. Remove seedling(s) from the starter pot

Use a dibbler or wooden stick to extract seedling(s) from starter pots. If there is more than one seedling in a pot, gently separate the seedlings with a firm hand. 

Avoid handling or gripping the stem; grab the first leaves (cotyledons) or hold the seedling gently between your fingers, cupping the leaves.

3. Cut off first leaves (cotyledons)

Use a sharp pair of scissors to cut off the first leaves or cotyledons

4. Plant tomato seedlings deeper than they were growing

Cotyledons are cut to allow us to plant the seedlings deeper
Transplanting seedling deeper than it was growing before

Hold seedlings by the roots and plant them deep in your pot.

Deeper is better as long as leaves do not have contact with soil.

When the seedling is planted, fill the hole with soil and firm gently with fingers.

Roots will develop all along the stem, which is why it is essential to plant the seedlings deeper than they were growing before.

And this is also why we removed the first leaves (or cotyledons) in step 3 above.

5. Water thoroughly

Water thoroughly to help the root system get established in its new growing environment. Bottom watering by placing the pots in a water bath is our preferred technique.

Watering helps the seedling to recover from any form of transplant shock while also helping to compact the soil and remove any unwanted air pockets surrounding the root system.

6. Place in a well-lit location

A sunny window sill can work, but for us, grow lights are needed early in the year. Position your seedlings an inch or two below your grow lights and maintain that distance as the seedlings grow and develop.

If the distance between seedlings and grow lights is too great, the seedlings will stretch towards the light. The result will be leggy seedlings with thin, weak stems. We use a timer and keep our grow lights on up to 16 hours a day. It is, however, essential to remember that the plants also need a rest at night. 

7. Water and keep the soil moist 

Water your pots from the bottom and keep the soil moist but not wet. As the seedlings get established in their new growing environment, you can start feeding your seedlings a liquid fertilizer once a week. 

Remember that it is better to give your tomato plants a lower dosage regularly than one massive feeding. Follow the label directions when diluting the fertilizer. We always start with a lower dosage than recommended and work our way up to the recommended dosage. 

Transplanting one or several seedlings from a pot

When growing tomatoes from seed, you can choose to germinate seeds before planting or plant one or several seeds per pot.

When you pre-germinate seeds, you know you are only planting viable seeds. And when you know that each seed will sprout and grow into a plant, it, of course, makes sense only to plant one seed per pot.

Also, sometimes seeds are scarce, and you may only have a limited number of seeds to plant. Here too, in this scenario, it makes sense only to plant one seed per pot.

But most of the time, most of us plant two or more seeds per pot. This way, we improve our chances of having at least one viable tomato plant per pot. 

Should I transplant all or cut weaker tomato seedlings?

We always transplant all seedlings from every single pot. And yes, on occasion, this means transplanting up to 5 seedlings from one single pot.

Look at our instructional video to learn how to transplant more than one tomato seedling from one individual pot.

The alternative to transplanting all tomato seedlings is to use a sharp pair of scissors and cut the weaker seedlings just above the soil level. Cutting weaker seedlings will effectively always give you one seedling per pot, even if you initially plant several seeds per pot.

When to transplant tomato seedlings

The rule of thumb is to transplant tomato seedlings when you see a minimum of four true leaves (two pairs of true leaves). 

However, this may not be possible if you have several seedlings in the same pot. 

When you have several seedlings per pot, you will have stronger and weaker seedlings. 

Here we follow the rule to look at the weakest seedling. When the weakest seedling has (at least) one pair of true leaves, we feel confident in transplanting all the seedlings. 

The only exception to the rule is when the weaker seedlings are lagging in development to the extent that the more robust seedlings start to suffer. When this happens, we always cut the more fragile seedlings.

How do you know if stronger seedlings are suffering? Look at the color, firmness of leaves, and overall strength and vigor. And to be honest, it is pretty easy to spot. Just remember to check your seedlings daily, as early detection is vital.

I used to look for tomato plants to reach 10 cm / 3 inches before transplanting. But, as most tomato varieties grow differently I have found it easier and more reliable to use the two pair of trues leaves technique. 

Use fertile soil that drains well.

Transplant your tomato seedling into a pot with compost-rich fertile soil that drains well. 

Your seedlings will need nutrients to grow and develop, but it is enough to use good quality soil with compost. There is no need to add fertilizer when you transplant your seedlings.

Instead, ensure you water thoroughly to help the root system get established in its new growing environment.

When your seedlings are established in their new pots, you can start adding fertilizer. And as always, start slow. I recommend using half the recommended dosage when you start and then ramping up to the recommended dosage.

Remember, you can always add, but it is hard to take away. Also, tomatoes respond better to being fed smaller doses of nutrients regularly compared to one or two massive feeding per growing season.

Mastering the art of watering tomatoes

Tomatoes are thirsty and will, at the height of summer, sometimes need watering up to three times a day.

Still, tomatoes will not tolerate soaking wet soil. Seeds will not germinate, and root systems will drown or rot.

Moist but not wet is vital. Bottom watering seedlings is always best, but top watering will, of course also work as long as you do not get water on the leaves.

The key is to use soil that drains well and to give each tomato plant enough soil to develop. For smaller tomato varieties like cherry tomatoes, it is enough to use 10 liters / 2,5 gallons of soil. But for larger tomato varieties like the striped stuffer beefsteaks, I recommend using grow bags for tomatoes with a minimum capacity of 20 liters / 5 gallons of soil per plant. 

When you give each plant enough soil, you will find it a lot easier to manage soil moisture. And maintaining soil moisture is key for your plants to grow and develop. 

Transplanting tomatoes is a process.

We transplant our tomato seedlings to slightly larger containers two to three times while nurturing our plants indoors. And this is why I refer to transplanting tomatoes as a process. 

We like to plant medium and larger tomatoes in grow bags when they reach 30 cm / 1 foot as it allows us to keep them in the same grow bag and automatically pot them up as the plant grows. Watch our video tutorial for more information: Grow tomatoes in grow bags & never re-pot tomato plants to larger pots again.

Transplanting makes for healthier and stronger root systems and helps us manage the space available when we are confined to growing indoors. 

And always support your plants using stakes or tomato cages for strong and healthy plants.

Meet the author: Mattias is an experienced gardener spending most of his free time on his knees among herbs, plants and garden vegetables. For the past two years he has been sharing gardening projects and how-to tutorials on the NordicLavender website and YouTube channel.