How Tall Do Indeterminate Tomatoes Grow

If you’re growing tomatoes, one of the first things you need to know is if your plant is determinate or indeterminate. This difference is huge, especially when it comes to their height. So, how tall do indeterminate tomatoes grow? They can reach impressive heights, often soaring to 6 feet or much taller with the right care.

Unlike bush-type determinate tomatoes that grow to a set size, indeterminate varieties are vigorous vines. They keep growing and producing fruit until frost stops them. This means their final height isn’t fixed—it’s up to you, your season length, and your gardening setup.

The simple answer is: it depends. In a typical home garden, an unstaked indeterminate tomato might sprawl 4-6 feet wide. But when supported properly, heights of 8 to 12 feet are common in a single season. In ideal greenhouse conditions with a long growing season, some can even exceed 20 feet!

Your local climate is a major factor. A gardener in Florida has a much longer growing window than someone in Maine. The longer the warm season, the taller your plants can get.

What Influences Their Ultimate Height?

Several key factors determine just how tall your tomato vines will climb.

Variety: Some are naturally more vigorous. ‘Sungold’ and ‘Super Sweet 100’ are famous for their explosive growth, while many heirlooms grow steadily but strongly.
Sunlight: Tomatoes need full sun—at least 6-8 hours daily. More sun equals more energy for upward growth.
Soil & Nutrition: Rich, well-draining soil is essential. Regular feeding supports continuous growth. Poor soil stunts plants.
Watering: Consistent moisture is crucial. Deep, regular watering prevents stress and keeps growth on track.
Support System: The type of support you use literally sets the limit. A short cage will restrict them, while a tall stake or trellis encourages height.

Choosing the Right Support for Tall Tomatoes

Providing strong support is non-negotiable for indeterminate tomatoes. It prevents disease, keeps fruit clean, and manages that impressive vertical growth.

Tall Stakes (6-8 feet): Use sturdy wooden or metal stakes. Tie the main stem loosely every 12-18 inches as it grows.
Tomato Cages (Heavy-Duty): Avoid flimsy store-bought cages. Use large, welded wire cages or concrete reinforcing wire cylinders that are at least 5 feet tall.
Vertical String Trellis: Great for gardens with multiple plants. Strings hang from a high wire, and you wind the plant up the string. This method can support very tall plants.
A-Frame or Panel Trellises: These are both sturdy and attractive, offering excellent air flow and easy access to fruit.

Step-by-Step Guide to Managing Their Growth

You can’t just let them grow wild. Here’s how to manage them for a healthy, productive, and tall plant.

1. Planting for Success

Start with a deep planting hole. Bury the stem up to the first set of true leaves. This encourages a stronger root system right from the start, which supports better top growth.

2. The Art of Pruning (Suckering)

Pruning is the main way you control an indeterminate tomato. You typically grow them as a single main stem.

Identify the “suckers.” These are small shoots that grow in the V between the main stem and a branch.
For tallest growth, remove all suckers regularly. Pinch them off when they’re small (1-2 inches).
This directs all the plant’s energy into the main stem and fruit production, not into extra leafy branches.

Be careful not to over-prune in hot climates, as leaves provide essential sun protection for the fruit.

3. Tying and Training

As your plant grows, you must tie it to its support. Use soft plant ties, cloth strips, or tomato clips. Tie loosely around the stem, just below a branch junction, to avoid damaging the stem. Check and adjust ties every week or two during peak growth.

4. Feeding and Watering for Height

Indeterminate tomatoes are heavy feeders because they’re growing and fruiting for months.

Use a balanced fertilizer at planting.
Switch to a fertilizer higher in potassium and phosphorus (like a 5-10-10) once flowers appear to support fruit set and continued growth.
Water deeply 1-2 times per week, depending on weather. Consistent watering prevents blossom end rot and keeps growth steady.

What to Do When They Reach the Top

Eventually, your plant will hit the top of its support. You have a few options:

Top the Plant: Pinch off the very top growing tip. This signals the plant to stop growing upward and focus on ripening existing fruit. This is a good strategy as fall approaches.
Let it Cascade: If using a string trellis, you can lower the string a bit (if possible) or allow the top to grow back down. This works well in greenhouses.
Redirect Growth: Gently guide the top growth back down or along a horizontal wire if your setup allows it.

Common Challenges with Tall Tomato Plants

Growing giants comes with its own set of issues. Here’s how to handle them.

Wind Damage: Tall plants act like sails. Ensure supports are driven deep into the ground and are very sturdy.
Harvesting Difficulties: Use a step stool to safely reach the highest fruit. Never yank on the vine.
Increased Water Needs: The taller the plant, the more water it needs to transport moisture to the top. Don’t let the soil dry out completely.
Pest Monitoring: It’s easy to miss pests like hornworms at the top of a huge plant. Make a point to inspect the entire plant weekly.

FAQ: Your Questions Answered

How fast do indeterminate tomatoes grow?
In peak summer heat, they can grow several inches a week. Growth is slower in cooler spring and fall weather.

Can I grow indeterminate tomatoes in pots?
Yes, but choose a very large pot (at least 15-20 gallons) and a compact variety. They will not reach the same heights as in-ground plants due to root restriction.

What’s the tallest indeterminate tomato on record?
Record heights are over 65 feet, but these are grown in perfect controlled conditions. Don’t expect this in your backyard, but aiming for 8-10 feet is very realistic.

Do I have to prune them to get them tall?
Pruning to a single stem is the most effective method for maximizing height on a given support. An unpruned plant will get bushy and wide, not necessarily taller.

When should I stop letting my tomato plant grow taller?
A good rule is to top the plant about 4-6 weeks before your area’s first expected fall frost. This gives the last fruits time to ripen.

Growing indeterminate tomatoes to impressive heights is a rewarding part of summer gardening. It’s a fun challenge to see how tall you can get them. With the right support, consistent care, and a bit of pruning, you’ll be amazed at what these vigorous plants can achieve. Just remember to keep your step ladder handy for the harvest!