How to grow tomatoes in pots and containers

Tomatoes and lettuce have to be the holy grail of all gardeners. Here today we will focus on how to grow tomatoes in pots or larger sized containers.

You will find easy to follow tips and instructions whether you grow your tomatoes from seeds or buy plants at your garden center.

Tomatoes are not difficult to grow. As long as you water your plants you should have tomatoes to harvest.

But with a little bit of extra knowledge your plants will yield much healthier harvests.

Tip: Skip forward to “4. Moving tomato plants to their final growing place” if you are using tomato plants bought at your garden center.

1. Choosing witch type of tomato to grow

Tomatoes on longer indeterminate plant
Tomatoes on indeterminate plant

First we need to decide which type of tomato we will grow.

And I am not just referring to size, shape and color.

If you are living in a cooler climate it is wise to choose a variety that develops and matures earlier.

You should also factor in how cold hardy the plant is.

Generally speaking bushy tomato plants (determinate) and dwarf tomatoes develop earlier. But you will find specific information on the seed packet.

Tomato plant are determinate and indeterminate. Determinate plants are bushy and do not grow tall. We only prune or trim determinate plants after they start producing fruit.

Indeterminate tomato plants develop slower and grow tall and long. Indeterminate tomato plants need a lot of support as they grow and are ideally placed against for example a wall.

2. Planting the tomato seeds

When we have our tomato seeds we plant them in starter pots. Place one or two seeds per pot and cover lightly with soil.

Do not overwater. Use a spray bottle to keep the soil moist. 

Your soil should be moist, not soaking wet. Cover your pots with plastic or put them in a mini greenhouse if possible. Ensure air can circulate if you cover your pots.

Use potting soil that is not too rich in nutrients. I use a 50/50 blend of regular garden soil with the top half of the pot filled with leaner Cactus soil. But any leaner potting mix will do.

Plant your seeds about 6-8 weeks before you are planning to move them outdoors.

Planting earlier in the year is not always better as the seedlings will need light to develop. If there is not enough light the young plants will grow tall and leggy in their search for light. 

You may also get leggy plants if you fertilize the young plants too much. Wait until the tomato plant is strong and established before adding nutrients. 

The seeds will germinate in 7-14 days in temperatures around 20-25 degrees Celsius (68-77 degrees Fahrenheit).

3. Looking after the tomato seedlings

When the seeds start to germinate and sprout first leaves we move the pots to a location with a lot of light. A window sill can be an ideal location.

Keep the soil moist and be careful not to water on the leaves. If you have several pots it can be easier to water the pots from the bottom. Simply place them in a water bath and let the soil absorb the moisture.

If your tomato leaves turn white or yellow you could have a problem with overwatering.

With smaller type starter pots it takes less than 10 minutes to water the pots from the bottom.

4. Transplanting tomato seedlings into a larger pot

When you see two pairs of true leaves it is time to move the seedlings to larger pots.

I use plastic pots measuring 10 centimeters (4 inches).

Young seedlings now need more nutrients. Plant the entire seedling with the root system intact into richer garden soil. 

When you plant the seedlings in the pot gently place them on top of the new soil. Do not press them down as the root system needs air to develop and thrive.

Next, fill up the pot with new more nutrient-rich garden soil. Here we press the new soil gently to remove any pockets of air.

There are specialized soils for tomatoes but I have personally never used them. I use my own 5 component soil mix but any good quality garden soil will do just fine.

At this stage, it may be necessary to add sticks to support the young plants. You always want to avoid the plants falling over with leaves touching the soil.

4. Moving tomato plants to their final growing place

When the root system of the tomato plants fill the entire pot it is time to transplant them into a larger pot or container.

This is also where you start when you buy tomato plants at your local gardener. 

Tip: When you buy tomato plants you should replant them into new pots as soon as possible. You will find that the root systems are almost too big for the pot they came in as garden centers will use a smaller pot when possible to be able to put more plants on display. 

When you choose your pot it is always better to go big. Tomato plants need space to thrive and develop. It is also easier to manage water levels in a larger pot where smaller pots will dry out quicker.

Transplant your tomato plants in 3 easy steps.

1. Select a pot or container
Select a large pot or container with drainage holes. Now fill half the pot with well-drained and nutrient-rich garden soil. Cherry tomatoes can be ideal to grow in hanging baskets.

2. Move your tomato plant
Placing the plant deeper than before will allow new roots to form and result in a stronger tomato plant. 

Fill the rest of the pot with the new soil. Press gently on the new soil you added around the plant.

Do not press down on the actual tomato plant as the root system needs air and the soil should not be too compact. 

3. Water plant thoroughly
Do not water on the plant itself. Water gently around the plant and let the water be absorbed. When you see water coming out from the drainage holes you are done.

Tip: When you water without a rose you risk displacing too much air when the soil is literally attacked by the oncoming water. You need a balance of air and water for the root system to thrive. When we water more gently with a rose the soil has time to absorb the water without losing too much air and structure. Watch out for white or yellow tomato leaves signalling a potential problem with overwatering. 

5. Moving the tomato plants outdoors

We are now ready to start planning the move outdoors for our tomato plants.

Tomatoes will not tolerate frost and do not like cold weather. You should be looking for the temperature to stay above 10 degrees Celsius (50 degrees Fahrenheit).  And yes, this includes nighttime.

Before moving the plants outdoors you need to harden the plants. 

Start by moving the plants outdoors for a couple of hours and then add a couple of hours every day. It usually takes me about 5-7 days to prepare and harden my tomato plants for their move outdoors.

When the tomato plants are hardened you should look for a sheltered location with lots of sunlight.

Tomato plants do not like wind. They do however like sunlight and thrive if you can provide a minimum of 6 but ideally 8-10 hours of sunlight. 

6. Looking after your tomato plants

Tomato plants love sunlight but do not like to dry out. This is one of the reasons why we chose larger pots or containers.

Help pollinate tomato plants
Shake flowers gently to help with pollination

Keep the soil moist but not soaking wet. You can overwater your tomato plants and literally drown or rot the root system. Yellow leaves can be a sign of both under- and overwatering. But you will of course know where you went wrong.

Tomato plants like consistent watering so try to find a pattern where you water morning, evening or both during hot periods. Avoid watering during the hotter times of the day.

When the plant starts to bloom we can help the plant along by hand pollinating our tomato plants.

It may sound technical but all we do is to gently shake the plant or the clusters of flowers. Wind and insects will do their bit to help but there is no reason not to speed up the process. 

7. Harvest Ripe tomatoes & the late green tomatoes 

Tomatoes are one of those vegetables where homegrown by far outperform tomatoes you buy at the supermarket.

Harvest your tomatoes as they ripen. To harvest “plant to plate” is a great principle but is difficult as you will have many tomatoes that tend to ripen around the same time. 

Keep your harvested tomatoes at room temperature in your kitchen. Do not put them in the fridge where they will lose their flavour.

And then there is of course the matter of those late developers. You know what I mean. Those lovely looking tomatoes that are still green when the plant starts to dwindle and die. 

Put harvested green tomatoes on your windowsill and let them mature and ripen naturally.

Also, did you know that “Fried Green Tomatoes” is not only a movie. It is also delicious. Try it – you will be pleasantly surprised. 

Green tomatoes are also perfect to use for marmalades and chutneys if you or someone in your family are so inclined. 

Frequently asked questions

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.