How to Grow Tomatoes in Containers – Green Planet Naturals

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How to Grow Tomatoes in Containers

 tomato bumper crop

A new growing season is underway... And if you haven't already, it’s time to start thinking about your tomatoes.

After all, it doesn’t feel like summer without at least one lush, fragrant tomato plant growing in the garden. Maybe you’d like to grow an enormous plant with an endless supply of tomatoes, or a hanging basket overflowing with small, tidy clusters of colorful cherry tomatoes, growing outside the window where you can easily pick them for your summer salads. Perhaps you’d like several varieties, to keep things interesting.

Despite being notoriously finicky, tomatoes do quite well in containers if you know how to care for them...

But before we get to caring for your plants, let's make sure we give them a solid foundation.

We'll cover the pre-tomato checklist including choosing…

  • Which type of tomato you should be growing
  • Your container
  • The right potting soil

And then we'll cover what you need to do to keep them happy, healthy, and producing your best crop yet, including:

  • How to care for your plant
  • Pruning for plant health
  • Troubleshooting and common issues

Let's dig in!

The Pre-Tomato Checklist...

Choosing Your Tomato

Before we do anything, you'll want to have an idea of what type of tomato you're going to be growing. If you're serious about a bumper crop of tomatoes, cherry tomatoes are the way to go. They tend to produce more and yield a greater number of harvests throughout the season.

However, for many people, there's nothing so delicious as a thick, meaty, beefsteak tomato.

Part of your selection should be guided by how much space you have—and how much you want to dedicate to your tomato crop. Determinate plants (which have growth limits) won’t need as much space as indeterminate plants, which grow continuously (but also produce a higher yield).

While there are any number of great heirloom varieties for container gardening, here are a few of our own favorite determinates...

Cherry Tomato Varieties

  • Minibel - These adorable little plants grow to be about a foot high and require no support cages or rigging, making them a great choice for a relatively low-maintenance tomato. They even do well indoors!
  • Microtom - Southern Living named them to their list of 8 Great Plants You Gotta Grow, and it's easy to see why: these delicious little fruits are the world's smallest tomato, with each fruit growing to a perfect 1-in diameter. Perfect in salads, they do well in window boxes as well as hanging baskets.

These varieties all do well in small pots OR hanging baskets, making them perfect for small space gardeners.

Prefer a larger variety, perfect for summer BLTs? You might want to look at these...

Medium-Large Tomato Varieties

  • Manitoba - True to their namesake, these hardy heirlooms hail from Manitoba and are perfect for cooler climates. The short summers of their homeland make them quick to produce and ripen, for a sizable plant that packs quite the harvest. These determinates produce medium tomatoes that typically weigh in around 6 oz each.
  • Bush Champion - Looking for something... Larger? These delicious tomatoes weigh in between 8 and 12 ounces each, and are just the right combination of juicy and meaty. This determinates variety caps out at 24 inches tall, so while it will need a bigger pot and some stakes, it won't take over your balcony.

Choosing the Container - It's all about those roots...

Tomato plants have an extensive root system, so each plant should have its own container. The container size depends on how large of a plant you are planning to grow.

For Determinates

  • Small determinate plants require a depth of only 10-12 inches.
  • Medium and large sized determinates need containers that are at least 12 inches wide and 18 inches deep.
For Indeterminates

For any type of indeterminate plant, the container size should be at least 18 inches wide and 2 feet deep. Plants with large fruit, such as Beefsteak, need a 5 gallon container to grow properly.

Containers by type

Anything made of plastic work well. The pots should have drainage holes at the bottom. If there aren’t any, you can drill them into the bottom or on the sides one inch above the bottom. Plastic storage containers tend to be less expensive than the large pots found in garden centres.

Hanging baskets make good use of vertical space. Certain tomato varieties, such as Tumbler, are designed specifically for baskets.

Upside down tomato planters also work well for cherry tomato plants. The only difference between those and right-side-up planters is that you don’t need to add stakes and you water the plant at the roots instead of at the top.

Selecting Your Soil

Choosing your potting soil may be the most important thing you do to ensure a healthy, hearty crop of tomatoes this season. It is literally the foundation on which the rest of your gardening efforts rest.

Say no outdoor soil

As tempting as it may be to go dig up some soil outside, do not use outdoor ground soil for your tomatoes. It will be far too dense for container gardening and will lack the amendments that ensure good drainage, which will be a recipe for all sort of problems:

  • Preventing your tomato plant's roots from expanding into a healthy stable root system
  • Starving the roots for oxygen, which can lead to root rot
  • Making it difficult for water to sink down and reach the plant's roots as well as...
  • Making it difficult for the container to drain

Any soil that packs down too tightly is going to contribute to a host of problems for your plants, that can easily be avoided by using a high quality potting soil.

Ground soil is also more likely to contain unwanted insects, weed seeds, or contaminants that can cause damage to your delicate plants.


Using a high quality potting soil ensures that your tomatoes get a good start and plenty of drainage. We recommend using our Acidic Planting Mix
, which includes compost to give your tomatoes the right start, and is specially designed for container gardening's drainage and nutrient needs.

Proper Planting for Container Tomatoes

planting your tomatoes

Whether you opted to start your plants from seed, or got a head start by buying them from a local greenhouse, how you plant them in their final container is an important part of setting the foundation for a bumper crop of tomatoes.

Let's take a look:

  1. Prepare the containers. If you like, you can improve drainage by adding river rocks, Styrofoam peanuts, or bits of broken pottery to the bottom of the container.
  2. Fill the container with potting soil until it is almost full. Leave about an inch of space from the top so that excess potting soil won’t spill over the edge during watering.
  3. Scoop out a hole in the soil to make room for the base of the plant. Bury it to the lowest set of leaves. Roots will eventually form along the buried stem.
  4. Give it some support. Add a stake, trellis, or tomato cage for support, unless growing an upside down tomato planter. Keep in mind that indeterminate varieties, especially those with large fruit, will need the most amount of support.

And remember: Tomato plants and seedlings are ready to go outside when night-time temperatures are above 55° Fahrenheit. As Mike McGrath of You Bet Your Garden fame says: “Gardening cowardice has always served me well.”

So don't be afraid to leave your tomatoes sheltered inside a little beyond your last average frost date. And if you want to read more of Mike's tips on happy tomatoes, you can find them here.

Caring for Your Container Tomatoes

Pick a sunny spot

Tomato plants LOVE the sun. Place the container in a sunny location that gets at least 6-8 hours of direct sunlight daily.

Pro Tip: Tomato plants love sun, but the fruit, not quite so much. When pruning your plant, be sure to leave enough leaves on it to shade the fruit itself!

Water them daily

Because containers tend to dry out much more quickly than in-the-ground gardens, it's important to check them daily. It takes a lot of water to make a delicious, sweet, summer tomato, so you will likely find yourself watering daily.

  • Water until you see a small amount of water draining out of the bottom of your container, to ensure you've adequately saturated the soil.

Pro-tip: To reduce the risk of disease (or scorching the leaves in the hot sun), be careful to avoid getting water on the leaves. Using a watering can with a regular spout vs. a shower-type head goes a long way here.

Feed them well

Fertilize your plants every two weeks. We recommend a fertilizer designed specifically for tomatoes, like our Fish Bone Meal Fertilizer. The high phosphorous levels stimulate fruiting vs. leaf growth, important if you're trying to get a record haul from your container garden.

Pro Tip: Most fertilizers that you'll find at your local hardware store are going to be meant for lawns and flower gardens, and are high in nitrogen which encourages leafy growth instead of fruit development.

Of course, if you need any help deciding which fertilizer is best for your tomatoes, we're happy to help!

Keep that support coming

Indeterminate plants will grow many long branches. To keep them off the ground, tie them onto the stake or other support structure. Plant ties are available at garden centers or in gardening sections of home improvement stores.

Pro Tip: Some gardeners prefer to use old pieces of pantyhose that have been cut into strips, as they are readily available at home, and won't dig into the plants as they grow.

Pruning for success

Pruning helps ensure a hearty crop of tomatoes in a couple of ways...

  1. It allows the plant to concentrate its resources on making fruit, not supporting extra leaves and stems
  2. Removing leaves close to the bottom of the plant reduces the risk of disease and blight from traveling up the plant and jeopardizing your crop

So how do we prune?

It's simple, really... Just pinch off the suckers (shoots) growing in the notches of the stems, and trim off any leaves that are touching the soil and potentially lying wet. This extra foliage takes energy away from fruit production.

Close to the end of the season, pinch off the top of the main stem to encourage the ripening process. Remove all the flowers, extra leaves, and extra side branches. This way, the plant can concentrate on developing more fruit.

Harvesting

Pick the tomatoes when they are completely red (or yellow, or orange, or purple, if you are growing a non-red variety). They should twist off the stem easily.

Frost becomes an issue at the end of the growing season. The plants can survive light frosts if you cover them with fabric at night. However, you should pick all tomatoes (green ones too) before the first hard frost.

Green tomatoes that have started to turn colour will continue to ripen at room temperature. And of course, any that don't can still be delicious in any number of great recipes.

Troubleshooting: Common Issues

Tomato plants are prone to certain problems. Some varieties (usually hybrids) are resistant to disease, but no plant is immune to everything. Here are a few things to watch out for.

Blossom-end Rot
Blossom-end rot is caused by lack of calcium, which usually occurs when the tomatoes aren’t watered regularly. It will show up as a black spot on the blossom-end part of the plant. It can be prevented by watering the plant regularly. To treat an active case of blossom-end rot, apply calcium to the leaves themselves.




Aphids
These are tiny insects that eat the leaves. Spray them off with water. If they return, spray again with insecticidal soap.We recommend
making your own natural insecticidal soap, to avoid applying harmful chemicals to your food.

 

  

Tobacco mosaic virus
This virus affects tomatoes and other members of the nightshade family. It causes stunted, distorted growth and can significantly reduce the crop yield. Since it is caused by contact with tobacco and by people who have handled tobacco, the best method of prevention is to avoid smoking or chewing tobacco in the garden. Smokers should always wash their hands before handling plants or garden tools.

Once a plant has been infected, the virus can be spread by insects. There is no cure, and the virus can remain in the soil for years. If your plants become infected, make sure to discard the soil and thoroughly wash the container before starting another crop.

Tomato hornworms

These caterpillars will eat the plant’s leaves and fruit. Smaller hornworms should be sprayed with Bacillus thuringiensis (Bt). Grown caterpillars can be picked off by hand.

 

 

Cracked tomatoes
Cracking occurs when the plant is watered excessively after a long dry spell, especially if the tomatoes are in the middle of a growth spurt. Cracked tomatoes are safe to eat, but they are more prone to infection and should be picked sooner rather than later.

Prevent cracking by watering the plants regularly. If you are busy or forget to water the plants for several days and the soil becomes dry, you can avoid shocking the skins and reduce the chance of cracking by watering small amounts each day. Once the plants have recovered, resume your regular watering schedule.

Time to get growing!

Now that you're armed with everything you need to ensure your highest yielding tomato crop yet, it's time to get growing! For help selecting soils, fertilizers, or any other questions on getting the most from your plants this year, we're always here to help.

Get in touch to ask us a question!

And of course, if you're wondering what to do with all of those delicious tomatoes you're about to have, this roundup of recipes should get your tastebuds going.

 

Add them in the comments!


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