How to Grow Tomatoes in Pots: The Size Everyone Quotes Is for a Different Plant

The pot size, and the catch that comes with it

A 14 to 20 inch container works, and so does a five-gallon bucket with holes drilled in the bottom. That's Clemson's guidance and it's the number everybody quotes.

Here's the part that usually gets left off. Clemson gives that size for compact cultivars. In the same breath it says an indeterminate tomato "will not be successful in a 12-inch pot", because those plants "continue growing taller until frost, making them difficult to grow in containers." Two different plants. Two different pots.

So five gallons isn't wrong. It's an answer about a small plant, and most people asking have bought a big one. That mismatch is the whole problem. It shows up in July, when the plant stops filling out and starts wilting between waterings.

We hold 115 tomato varieties. 83 are indeterminate. That's 72%. The odds are against the pot you were told to buy.

Determinate or indeterminate, and why the label may not settle it

There are two kinds of tomato plant. In a pot they behave nothing alike.

Determinate plants "set fruit over a shorter time frame and stop growing" — Clemson's words. They reach a size, make their crop over a few weeks, and stop. That's the plant a five-gallon bucket was sized for.

Indeterminate plants keep going until frost stops them. There is no built-in end. Better Boy, Early Girl, Rutgers, Brandywine and Cherokee Purple are all indeterminate, and Clemson names those five as difficult in containers. Most heirlooms are indeterminate too. So is most of what a garden center stocks.

And knowing it says "determinate" isn't quite enough. Clemson again: "Not all determinate cultivars will have a compact habit, so refer to the plant height on the label for guidance." So the tag can be right and still not answer your question. The number that decides your pot is mature height. That's the one the tag most often leaves off.

If the plant will pass two feet, it needs a cage or a stake, and it needs it at planting. Clemson says to add support then rather than later. A cage pushed in around an established root ball does damage on the way through.

33 tomatoes that actually fit a pot

These are every determinate and dwarf variety in our database — the ones that reach a size and stop. Sorted by days to maturity, because in a container a short season is worth as much as a small plant.

One thing we can't give you, and it's the number Clemson says to look for: mature height. We hold it for 10 of our 115 tomato varieties. Where a seed packet or a plant tag prints a height, believe that over the habit label.

Determinate and dwarf tomato varieties from the GardenTrack database, with days to maturity from transplant.
Variety	Days to maturity	Habit
Tiny Tim	45 days	Dwarf · Small fruit
Fantastico	50 days	Determinate
Glacier	55 days	Determinate · Small fruit
Manitoba	58 days	Determinate · Medium fruit
Oregon Spring	60 days	Determinate · Medium fruit
Sub Arctic Plenty	60 days	Determinate · Small fruit
Bush Early Girl	63 days	Determinate · Medium fruit
Taxi	64 days	Determinate
Defiant PhR	65 days	Determinate
Husky Cherry Red	65 days	Dwarf · Small fruit
Roma VF	65 days	Determinate · Small fruit
Better Bush	68 days	Determinate
Bush Goliath	68 days	Determinate · Large fruit
Heinz 2653	68 days	Determinate
Sweet Tangerine	68 days	Determinate
Celebrity	70 days	Determinate
Green Grape	70 days	Determinate · Small fruit
Legend	70 days	Determinate · Large fruit
Mountain Pride	70 days	Determinate · Large fruit
Patio Hybrid	70 days	Dwarf · Medium fruit
Siletz	70–75 days	Determinate
Marglobe	72 days	Determinate
Bellstar	74 days	Determinate
Health Kick	74 days	Determinate
Martino's Roma	75 days	Determinate
Mountain Merit	75 days	Determinate
Plum Regal	75 days	Determinate · Small fruit
Rutgers	75 days	Determinate · Medium fruit
Viva Italia Hybrid	75 days	Determinate
Cream Sausage	80 days	Determinate · Small fruit
Homestead	80 days	Determinate · Medium fruit
Rio Grande	80 days	Determinate
Ace 55	85 days	Determinate · Large fruit

Why the small pot fails in July and not in May

A container tomato in May looks fine in anything. The plant is small, the roots have room, and the soil holds water for a day and a half. May proves nothing.

By July that plant has filled the pot with root and doubled its leaf area. Both changes work against you at once. Less soil holding water, more plant pulling it out. Clemson puts it plainly — containers that are too small "will create the need for constant watering, and the entire plant may even blow over from being too top-heavy with growth."

That's why it looks like a watering problem. It isn't. You can water a too-small pot twice a day and the plant still stalls, because what it ran out of is root room. Expect daily watering in high summer even when the pot is right — Clemson calls for close monitoring for moisture and daily watering at the height of summer.

What to do if the plant is already in the wrong pot

It's August and you have a six-foot plant in a bucket. Leave it there. Repotting now costs you fruit — a tomato with its roots disturbed in midsummer sulks for two weeks and drops flowers while it recovers.

So manage it rather than move it. Water daily, and deeply enough that it runs out of the bottom. Feed on schedule — a small volume of potting mix runs out of nutrients far faster than a bed. Get a stake in if there isn't one. And take the first ripe fruit off promptly — a plant carrying less weight puts less strain on a root system that's already short of room.

Then write down which variety it was. Next spring, that same variety in the right pot is a different plant. Only the container changed.

The short version

Buy the plant first. Then buy the pot to fit it, not the other way around.

If it's determinate and stays under about two feet, a five-gallon bucket or a 14 to 20 inch container is genuinely enough. If it's indeterminate — and seven in ten are — you want more soil than that, plus a cage in from day one. And the honest expectation that a pot holds a plant back compared to open ground.

Our tomato page carries the sourced spacing, timing and container figures we hold for the crop. For the date, when to plant tomatoes in your zone — a pot doesn't move the calendar.

Questions people actually ask

How big does a pot need to be for tomatoes?

Clemson puts a 14 to 20 inch container, or a five-gallon bucket with drainage holes, as suitable for compact cultivars. For an indeterminate variety that keeps growing until frost, that is too small — Clemson says such a plant will not be successful in a 12-inch pot and calls indeterminates difficult to grow in containers generally. Size the pot to the height the plant will actually reach, not to the seedling in your hand.

Can you grow tomatoes in a 5 gallon bucket?

Yes, if the variety is compact. A five-gallon bucket with holes drilled in the bottom is on Clemson's list of suitable containers for compact cultivars. Put an indeterminate variety in one and you get a plant that needs watering twice a day, stalls in midsummer, and may go over in wind from being top-heavy.

How do I know if my tomato is determinate or indeterminate?

The plant tag usually says, and if it does not, the variety name will tell you once you look it up — our list below covers 33 determinate and dwarf ones. Be careful with the label though: Clemson warns that not all determinate cultivars are compact, and says to use the plant height on the label for guidance instead. Height is the number that decides your pot.

How often do you water tomatoes in pots?

Daily in the height of summer, and Clemson says so directly — container tomatoes need close monitoring for moisture. Water until it runs out of the drainage holes rather than giving a little often. If you find yourself watering twice a day in July, that is usually the pot being too small rather than the weather being too hot.

Do container tomatoes need a cage?

Anything that will pass two feet does, and Clemson says to put the support in at planting time. A cage pushed in later has to go through a root system that is already filling the pot, and in a container there is nowhere for those roots to go.

Do tomatoes grow smaller in pots?

A tomato in a container is limited by the soil volume it has, so a plant that would reach six feet in the ground will usually do less in a pot. That is not a failure — it is the trade you accept for growing on a patio. Picking a variety that was going to stay small anyway is how you stop it being a compromise.

Sources

Every planting date, depth, and temperature on this page traces to these university extension guides. Where they differ, the ranges above hold the whole spread.

Clemson Cooperative Extension — Tomatoes in Containers
Clemson Cooperative Extension — Tomato

The variety list here is drawn from the same crop record behind our tomato page, which carries the sourced spacing, timing and container figures we hold for the crop.

If the container itself is the question rather than the tomato, what actually fits a five-gallon bucket works through it crop by crop from Maryland Extension's own table.

Pot size does not move the calendar. For the date itself, when to plant tomatoes in your zone counts it back from your own last frost, and the frost date lookup gives you that date for your address.