How to Tell If a Tomato Is Determinate Before You Buy the Seed

Short answer: if the seed description doesn't say determinate or indeterminate outright, check the listed mature height. Varieties around 24 inches to 4 feet are usually determinate or compact. Varieties listed at 6 feet or more, or with no height given at all, are usually indeterminate. The harvest description and the variety name give you a second and third check.Te

Here's how to use each of those.

We get this question all the time, usually right after someone learns that determinate tomatoes are the better choice for indoor growing.

Great. But which tomatoes are determinate?

That sounds like it should be easy to figure out, until you actually start shopping for seeds.

You pick up a packet or open a seed website and half of them don't say determinate or indeterminate anywhere. Now you're trying to figure out whether something like Sweet Million is going to stay a manageable size or spend the next few months trying to grow into your ceiling.

The good news is there are a few really easy ways to tell, even when the seed company doesn't make it obvious.

First, see if they just tell you

Some seed companies make this simple and put it right in the description:

Determinate. Indeterminate. Semi-determinate.

If it says determinate, you're good.

If it says indeterminate, we would normally skip it for an indoor garden, no matter how good the tomatoes sound.

You may also see some older gardening terms used instead.

Bush usually means determinate.

Vine, cordon, or pole generally mean indeterminate.

Then there is semi-determinate, which sits somewhere in the middle. These plants do eventually stop growing, but they usually get larger than a true determinate variety first.

Some semi-determinate tomatoes can work really well indoors. Others can become a little too ambitious.

We usually treat those as a "maybe" rather than an automatic yes.

If it doesn't say, check the height

This is probably the easiest clue.

A determinate tomato has a built-in stopping point. It grows to a certain size, produces its crop, and eventually stops getting taller.

Because of that, seed companies can usually give you a fairly specific mature height.

You might see something like:

• 24 inches
• 3 feet
• 3 to 4 feet

Those are good signs that you're looking at a compact or determinate variety.

Indeterminate tomatoes are different. They keep growing as long as the conditions allow them to.

So instead of a nice manageable height, you'll often see things like:

• 6 feet
• 8 feet
• 6 feet or more

Or sometimes they won't give you a height at all.

That missing height can actually be a clue.

So our general rule is:

If the variety has a modest, clearly listed height, it is more likely to be determinate or compact. If the height is very tall, open-ended, or missing completely, look into it a little more before buying.

Look at how they describe the harvest

The harvest description can give you another clue.

Determinate tomatoes tend to produce most of their fruit within a shorter period of time.

So you may see descriptions like:

Concentrated harvest

Ripens over 2 to 3 weeks

Great for canning

That last one is surprisingly useful. Canning varieties are often bred to produce a large amount of fruit around the same time, which is exactly what a determinate plant does.

Indeterminate tomatoes usually sound very different.

You may see:

Produces all season

Continues until frost

Continuous harvest

That tells you the plant is designed to keep growing and producing instead of finishing one main crop.

Variety names can give you clues too

Sometimes the name itself gives you a pretty good hint.

Words like:

• Patio
• Bush
• Dwarf
• Compact
• Container
• Balcony

usually mean the variety was bred to stay relatively small.

Tiny Tim is a great example and one we recommend often.

Red Robin is another popular compact variety.

Just keep in mind that words like "dwarf" and "compact" describe the plant's size, while "determinate" describes its growth habit. They often overlap, but they aren't exactly the same thing.

What about heirloom tomatoes?

This one is worth checking rather than guessing.

A lot of the famous heirloom tomato varieties are indeterminate and can become very large plants.

That doesn't mean every heirloom is indeterminate, though. There are determinate heirloom varieties as well.

So if you find an heirloom tomato you really want to grow, look up that specific variety before ruling it out.

What if the packet still doesn't tell you?

Sometimes you have a variety name and basically nothing else useful.

In that case, search the variety name along with the words:

determinate or indeterminate

Usually you'll find an answer pretty quickly from another seed company, university extension program, or gardening reference.

If you still can't find a clear answer, we would probably choose another variety.

There are so many good compact tomatoes available that it usually isn't worth gambling months of growing space on a plant that could become enormous.

One important thing people don't expect

There is one downside to determinate tomatoes that catches new indoor growers off guard.

They finish.

That sounds obvious once you know how they grow, but it can be surprising the first time you see it happen.

A determinate tomato can look fantastic, produce a heavy crop, and then slowly begin winding down.

That doesn't necessarily mean something is wrong with your nutrients, your lights, or your garden.

The plant may simply be reaching the end of its natural cycle.

The easiest way around this is to plan ahead.

Once your tomato is well into fruiting, start another seedling.

That way, when the older plant finishes, you already have a young plant ready to take its place.

It turns tomatoes from something you grow once into something you can keep cycling through your garden.

Where we buy our seeds

We get asked this a lot too.

We don't sell seeds, and that is intentional. Our systems are designed to take standard seeds, so you're not locked into buying proprietary seed pods or choosing from a tiny catalogue.

For our own growing, we regularly buy from West Coast Seeds in British Columbia and Mumm's Sprouting Seeds in Saskatchewan.

Both have been good companies for us to deal with, and having clear variety information makes choosing plants a lot easier.

Conclusion

Once you know what to look for, this stops being complicated.

Check the description first. If it does not say, look at the height. If there is no height listed, that is usually your answer.

Getting this right at the seed stage saves you months, because the alternative is finding out in week ten when a plant you cannot manage has taken over your garden.

And when your determinate tomato does start winding down, that is the moment to start the next one. Keeping a few rockwool grow plugs on hand makes that easy, so you can have a seedling ready before the old plant is finished.

FAQ

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

Start with the seed description. Many companies will tell you directly.

If they don't, check the mature height and harvest description. Compact plants with a clearly listed height are more likely to be determinate, while varieties listed at 6 feet or more are generally indeterminate.

When in doubt, search the variety name before planting it.

What does bush tomato mean?

Bush usually refers to a compact or determinate-style tomato.

Terms like vine, cordon, and pole are more commonly associated with indeterminate tomatoes.

Are determinate tomatoes better for indoor growing?

Usually, yes.

Their final size is easier to plan around, which makes them much simpler to manage under indoor lights or inside a hydroponic garden.

Indeterminate tomatoes can absolutely grow indoors, but they require considerably more pruning, training, and space.

What is a semi-determinate tomato?

Semi-determinate tomatoes fall between determinate and indeterminate varieties.

They eventually slow or stop their upward growth, but they usually get larger than a traditional determinate tomato first.

Some are great indoors. Others can still become too large, so check the expected height of the specific variety.

Are heirloom tomatoes determinate?

Some are, but many popular heirloom tomatoes are indeterminate.

Always check the individual variety rather than assuming based on the word heirloom.

How long does a determinate tomato produce?

Determinate tomatoes tend to produce a large portion of their fruit within a relatively concentrated period and then begin winding down.

That is part of their normal growth cycle.

For continuous indoor tomatoes, start a replacement seedling while the current plant is still fruiting so the new plant is ready when the old one finishes.