Well, indeterminate tomatoes are continuously growing, vine-like plants.
Determinate tomatoes, on the other hand, are more bush-like and limited in growth.
The difference between indeterminate and determinate tomatoes really is that simple.
What do the differences between indeterminate and determinate tomatoes mean to you as a tomato gardener?
That’s a bit more complicated.
As a tomato gardener, you’ll want to know whether each tomato variety you’re considering is a determinate or indeterminate plant.
Several important reasons:
If you don’t have a lot of space available for your tomato plot, you’ll probably want to stick to determinate varieties.
Because of the fact that indeterminate varieties grow continuously until frost (or until some other misfortune terminates the plant), each plant can end up requiring a lot of room before the end of the season.
For example, the indeterminate variety I grow in my greenhouse commonly reaches a length of twenty-five to thirty feet! Now, my greenhouse tomatoes are pruned to a single stem, meaning I remove all suckers and maintain just a single growing point. If you’re growing an indeterminate in your garden, you’ll probably let the suckers grow, so you’re not going to end up with a thirty-foot plant.
But a determinate will still take up a lot of space. Of course, that’s not a bad thing – unless you don’t have the space to spare!
Also, you’ll need to plan on providing more support to indeterminate tomatoes. If you don’t provide trellising and/or caging or staking, your indeterminate plant will end up sprawled out on the ground. It won’t mind growing that way, but you probably won’t like the jungly mess!
Most determinate varieties will require some support also – just not as much.
Desired Harvest Window...
Want to pick tomatoes from first harvest to frost? Plant indeterminates. Each indeterminate plant is like a little tomato factory that will just keep cranking out the tomatoes until something (like first frost) shuts the factory down.
Want to plant early, and get a big-but-brief harvest to beat the heat before the dog days settle in? Plant determinates. Each determinate plant’s genetics dictate that it will grow and produce only for so long, and then it pretty much shuts down. After the main crop, a determinate tomato plant might continue to live and struggle to crank out an occasional tomato. But its glory days are behind it, never to be revisited.
If you live in an area that has a long growing season, but it gets HOT HOT HOT – like here in Texas – a great strategy is to grow TWO tomato crops. Plant a determinate crop in the spring, and another in late summer. You can produce lots of tomatoes that way, but you’re not struggling to get plants to produce during the most miserably hot days of summer.
The Plants are Managed Differently...
In addition to allowing for the different growth characteristics of determinates/indeterminates, you’ll need to know not to prune the plants in the same way.
We’ll get into specifics on the page about pruning tomatoes. Just know that what’s proper management for indeterminate tomatoes is most certainly NOT proper for determinates (and vice-versa).
At the risk of complicating a simple subject, there’s one other thing I should tell you about indeterminate/determinate tomatoes: There’s actually a third category called semi-determinate.
There aren’t many semi-determinate varieties. But one of the most popular of gardening tomatoes, Celebrity, is a semi-determinate variety.
For the most part, semi-determinate tomato varieties are treated as determinate, and also perform more like determinate tomatoes. They’ll produce a large main harvest, and then may continue to produce a substantially smaller amount until frost.
If you’re determined to grow tomatoes, you’ll need to determine whether to grow indeterminate, determinate, or semi-determinate tomatoes before terminating your variety determining process.
(Sorry…I was just determined to put that line in before terminating this page!)