Tomatoes are the holy grail of gardens. Who can resist all those sweet, juicy orbs ripening in the sun every summer, filling the air with that unmistakable heady scent of tomato vine?
Hands down, it’s one of my favorite plants to grow every year and I grew it without abandon in my last garden, in the ground, when space was not an issue for these large, unwieldy plants.
But when I uprooted to a different part of the country and found myself in a rental home for the short term, with only a deck that was suitable for gardening, I thought my tomato dreams were dashed for the next couple summers.
That first year, I ended up growing a wide variety of tomato plants in containers, easily and successfully, in my hardiness zone 6b climate. I had enough of a harvest every week to eat fresh and cook with, and a final crop at the end of summer to preserve.
I found that an unexpected benefit of container plants is being able to protect them more easily from critters (in my case, growing tomatoes on a second-story deck deterred all the deer in my neighborhood), not to mention having better resistance against pests and diseases that naturally live in the garden (since you start with fresh potting soil).
Growing tomatoes in pots really levels the playing field in the home garden game, as it allows even gardeners short on space (say, a balcony or side patio) to grow beautiful and productive plants regardless of real estate.
The key to growing tomatoes in pots like a gardening pro is proper planning.
First, make sure you choose a location with at least 8 hours of sun (6 hours is the bare minimum, but more is much better).
Then, follow my tried-and-true tips below to learn how you can maximize the minimal space you have and cultivate healthy, vigorous tomato plants in your small-space container garden!
1. Choose the right type of tomato.
Determinate types (also called bush, compact, or patio plants) are usually the best tomato plants for containers, as they grow to a predetermined size — no more than 3 to 4 feet tall — and set flowers and fruits all at once, making them reliable and predictable in tight quarters.
However, you can still grow indeterminate tomatoes if you give them a large enough container and good support for their vines. (More on my favorite tomato supports below in Step 9.)
A good rule of thumb is to grow determinate tomatoes if you have a short growing season, got a late start in the season, or have a very limited footprint.
If, on the other hand, you have a decent growing season and enough space for a large, tall plant, indeterminate tomatoes will give you abundant harvests all summer long and are totally doable in containers!
2. Start with a strong and healthy transplant.
Ideally, the tomato plants you start with should have been repotted at least once, and hardened off properly so they’re ready to live outside in the sun.
Repotting assists your tomato plants in developing larger root masses, which in turn helps them survive the shock of transplanting, resist pests and diseases that prey on vulnerable young plants, and grow stronger overall.
If you’re bringing transplants home from a nursery or garden center, look for thick, sturdy stems and healthy green foliage free from insect damage, sunburn, and yellowing (which indicates watering issues or nutritional deficiencies).
I also try to avoid “top heavy” plants on tall, skinny stems, as it could be a sign they haven’t received adequate sunlight or been repotted.
3. Don’t be shy with container size, and choose a fabric pot over a plastic pot.
When it comes to tomatoes, the bigger the pot, the better.
Determinate varieties should be planted in 10-gallon containers at a minimum, while indeterminate varieties need, at the very least, 20-gallon containers to thrive. Any smaller than these sizes and your plants may not be as productive as they could be.
My favorite type of containers are fabric pots, like these ones from Root Pouch. They come in either non-degradable or biodegradable versions, but for container gardening, I prefer the non-degradable Boxer line so I can reuse them year after year.
Fabric pots are beneficial for plants with extensive root systems because they naturally “air prune” the roots.
The effects of air pruning in breathable fabric pots are best seen when compared side by side with plants contained in non-porous plastic pots.
When the roots in plastic pots grow long enough to hit the sides of the pot, they continue to grow round and round in a constricted pattern (spiraling, kinking, and twisting around themselves), eventually becoming rootbound.
Roots in fabric pots, on the other hand, are exposed to air as they grow. This exposure “burns off” the tips of the roots, which stops them from growing long and spindly. Instead, they branch off and form new, shorter, fibrous feeder roots.
Because growth is well distributed throughout the soil volume (and not just on the edges of the pot), the dense network of branched roots is able to increase the plant’s uptake of water, utilize all available nutrients, and aid in its natural defenses.
Image by Root Pouch.
The permeability of fabric pots also helps to promote proper drainage of excess water and improve oxygenation to the roots (which maximizes the plant’s metabolic performance and, in turn, boosts crop yields).
In cooler climates, however, black plastic pots do serve a practical function. They hold heat in and keep roots warm in late spring to early summer, when tomato transplants are most susceptible to temperature swings.
On the flip side, black plastic pots may get too hot in the peak of summer, so they need to be shaded to prevent the rootball from overheating. You can wrap or cover plastic pots with shade cloth, canvas, or towels to insulate against the heat (office binder clips work great for securing them), as well as try to keep them off heat-retaining surfaces like concrete.
Whichever kind of container you use, be sure to place a saucer (I use this one) underneath before you load it up. Not only will the saucer protect your deck or patio from standing moisture, it will allow your plant to absorb any excess water over the course of a hot day.
4. Use high-quality potting soil.
Plants in containers need a good combination of breathability, absorption, and moisture retention.
The topsoil from your garden (as well as any commercially bagged mix labeled as “raised bed soil” or “garden soil”) is generally too dense for potted plants, and it increases the risk of your tomato plant picking up a soil-borne disease that’s otherwise easily preventable.
I recommend using a high-quality premium potting soil or potting mix like this one, and try to avoid reusing potting soil from past seasons if your plants had pests or diseases.
Spread about 3 to 4 inches of potting soil on the bottom of your container, then continue with Step 5.
5. Feed your tomato plant well.
Tomatoes are heavy feeders and need ample nutrients to produce well and long into the season.
Before putting the tomato transplant in its final planting hole, add the following amendments to the soil and stir them around a bit:
- 1/2 cup of tomato/vegetable fertilizer
- 1/4 cup of fish meal
- 1/4 cup of bone meal
- 2 aspirin tablets
- Handful of crushed eggshells
Once the amendments are in, spread another 2 to 3 inches of potting soil on top.
6. Bury the stem of the tomato plant.
Gently pinch or snip off the lowest sets of leaves until you’re left with a bare stem on the bottom one-third to one-half of the stem.
Center the tomato plant in the pot and fill the remainder of the pot with more potting soil until it’s filled to the brim (just below the last set of leaves). Gently shake the pot to settle the soil and add more as needed.
Top off the soil with 1/2 cup all-purpose fertilizer (I like this one) and lightly rake it in around the base of the stem.
7. Water thoroughly and consistently.
Water the root zone thoroughly until the soil is evenly moist. I usually water the plant in, wait about 10 minutes, water again, wait 10 minutes again, and repeat until water runs freely out the bottom of the pot.
It takes a surprising amount of water (at least a gallon, from my experience) to saturate the soil fully the first time. Don’t assume that just because the water drains right away on the first watering that the soil is soaked.
Proper watering is the key to success when it comes to growing tomatoes in pots. Too little or too much water can stunt your plant’s growth, contribute to blossom end rot, or encourage pests in times of plant stress.
For those same reasons, water only the root zone (not overhead on the leaves) so you can see exactly how much water your plant is getting each time.
After the initial watering, and depending on the weather, you probably won’t need to water again until three days later. Check the first 2 inches of soil with your finger; if it feels dry, give it a good drink. As summer goes on, you’ll want to check the soil every day to ensure a consistent level of moisture.
Plants in containers tend to dry out more quickly than those in garden beds, so it’s not unusual to water once a day or more as temperatures climb higher. The smaller the pot, the more often you’ll need to water.
Remember that tomato plants like to be watered deeply, so be sure to saturate the soil until excess water drains out the bottom.
8. Protect young transplants from frost with “walls of water.”
Generally, it’s a good idea to wait until nighttime temperatures are consistently above 45°F before you plant tomatoes outside. But in climates with short or finicky growing seasons, sometimes you just need to get them outside sooner (or you never know when temperatures may dip below freezing). Here in Central Oregon, it’s not unheard of to get frost well into June!
One way that I protect my transplants in late spring to early summer is with “walls of water” (also known as tomato teepees). They keep plants nice and toasty and are super easy to use (no need to take frost covers on and off each day).
Walls of water enable you to plant your tomatoes up to six weeks before your last frost date, and keep them going up to six weeks after the first freeze, as they’re rated to withstand temperatures as low as 16°F. (They haven’t failed me yet, though I’ve personally never used mine much below 30°F.)
They also protect against wind, so they’re useful for delicate young plants that haven’t fully anchored themselves into the soil yet.
“Walls of water” is basically a large ring of heavy-duty plastic that’s sectioned off into long tubes. The tubes are filled with water, and the “walls” are placed over the plant with the weight of the tubes supporting them. You end up with what looks like a teepee around your plant.
(Quick tip: Place the walls of water over a bucket and fill the tubes partway with water until the walls can mostly stand on their own. Transfer the walls to your container over the plant, then continue filling them to the top with water.)
Walls of water act as mini greenhouses, collecting heat from the sun during the day and radiating it back out at night. They do need to be refilled periodically as the water evaporates, but they’re surprisingly effective in colder climates and I highly recommend using them if you want to get an early start on the growing season.
I usually remove mine once my tomato plants are a few inches above the walls (or I’m certain all danger of frost has passed).
A simple way to remove the tomato teepee is to push all the walls in until water spills out the top and onto the soil. Once the tubes are mostly empty, you can roll them down, lift them up over the plant, dry them out, and store them for next year. Then proceed with Step 9.
9. Add your support structure.
To reduce chances of damaging the roots, add your tomato support at this stage before the plant grows too large.
If you are growing determinate tomatoes, the metal conical cages that you find in most garden centers will suffice. But, I am generally not a fan of them for indeterminate tomatoes, as I find they’re too flimsy to support the long, sprawling vines.
My favorite tomato supports are these tomato ladders (essentially very tall, burly stakes) and square tomato cages (which can be folded down when not in use). Both of these supports are strong, extendable, and durable (I’ve used the same ones for years and they still look good as new) and they’re also attractive, if you care about that kind of thing.
(Quick tip: If you use tomato ladders, you can stake your plants first and then add the “walls of water” over them, making things a little more streamlined.)
They’ve easily supported my container tomatoes that grew over 7 feet tall and are convenient to store away at the end of the season. I’d say the cages are a little better at containing the vines than the ladders, as you can simply tuck your tomato branches back into the cage if they get too unruly.
With tomato ladders, you have to stay on top of tying or clipping the vines to the stakes to keep them neat and tidy.
Whichever support you use, don’t wait until you actually need it before you install it. It’ll be that much harder to wrangle a mature tomato plant into a cage than to just have it in place early.
10. Mulch the soil.
Mulching is essential for any garden, but it’s especially important for container gardens as it helps retain moisture in the soil.
Use an organic mulch like straw (not hay, which contains seeds) or shredded bark to cover the soil by at least 2 inches, taking care not to bunch it up against the stem. One substantial layer of mulch should last the whole summer, and can be composted with your spent tomato plants at the end of the season.
11. Fertilize your tomatoes consistently throughout the season.
Even with all that good stuff that you put in the planting hole, your tomato plants will need another shot of nutrients about six weeks into the season. I like to use a balanced organic fertilizer, like this granular tomato fertilizer or this liquid fish and seaweed emulsion. Follow the package directions for proper application, and keep the fertilizer bag or bottle next to your plants so you’ll never forget to feed them.
Try to avoid high-nitrogen fertilizers, as you’ll end up with lots of lush green leaves, but no flowers or fruits.
I have a deep love for growing any and all types of tomatoes in all kinds of conditions, so if you have any questions about growing tomatoes in pots, please ask away in the comments!