If you’re like me, you like to grow big, heirloom tomatoes. These flavorful, juicy varieties are gorgeous and rare, making them perfect to harvest from our backyard garden.
When it comes time to harvest, I want to get the biggest tomatoes possible. Over the past 10+ years of gardening, we’ve learned some easy tricks to grow larger tomatoes.
These techniques are shown to result in larger overall harvests and/or a larger fruit size. So, we always put these tips to use for the best possible results from our tomato plants! Let’s get into it.
1. Bury The Stem
When you are ready to transplant your tomatoes outdoors in the spring, there is one simple rule to remember. Always plant tomatoes in a deep hole, burying the stem by several inches.
Unlike some other plants that may rot at the stem, tomatoes will simply grow more roots from the buried portion of the stem. The result is a more developed and deep root system, shortly after transplanting outdoors.
These roots are called “adventitious” roots, and are incredibly common to see on tomato stems. You may have even seen adventitious roots on your tomato stems when the air was especially humid. All it takes is a bit of extra moisture, and tomato stems will readily send off new roots to anchor into new soil.
Don’t just take my word for it, a University of Florida study showed that planting tomatoes deeply had a positive impact on overall plant yield and fruit size. In the study, plants were transplanted to the depth of the first true leaves on each plant, and compared to others that were planted at the rootball depth.
So, when you’re ready to plant your tomatoes in the garden, try these steps:
- Dig a hole deep enough to bury the main stem, up to the first set of true leaves
- Drop your plant into the hole, surrounding the stem with soil
- Water deeply to ensure the entire plant is moistened
If your soil is not deep enough to dig a deep hole, you can also trench your tomato plants. To do this, lay your plants on their side for 1-2 days prior to transplanting. This will cause the main stem to curve upwards at the end.
Then, dig a long, shallow trench and plant the tomato sideways in the trench. Backfill the soil, burying the stem and roots. Water along the trench to ensure the stem and rootball are well watered. The effect should be similar, with a larger root system developing from the buried portion of the stem.
2. Prune Sucker Shoots
Sucker shoots are side shoots that develop along the main stem of tomato plants. They will grow into branches that can produce more tomatoes, flowers, and even more sucker shoots. In many cases (but not all), it is best to remove them from your plants.
First, figure out if you are growing determinate or indeterminate tomatoes. Your seed packet should have this information, or try checking seed websites. If you are growing determinate tomatoes, you can skip this step, as I don’t recommend pruning suckers from them.
However, if you are growing indeterminate tomatoes, pruning suckers is essential to better yields and tomato size. If left unpruned, sucker shoots “steal” energy from the main stem, leading to wild, messy plants that produce smaller tomatoes.
How to identify and remove tomato suckers:
- Look at the nodes of the plant (where a leaf is attached to the main stem) and look for shoots forming in between (these are suckers)
- Avoid removing leaves or flowering branches
- Prune suckers when they are small
- Prune regularly throughout the season
I generally only prune suckers from larger tomato varieties, and will leave many suckers on cherry and grape varieties. This is because the smaller tomato varieties don’t suffer from smaller fruits on sucker branches.
It is best to grow tomatoes vertically to keep your plants upright and off of the soil. Removing suckers naturally causes the plants to stretch upwards, so providing a trellis to attach the plants helps.
Using this method, you can plant tomatoes much closer to each other, typically around 12-18″ apart. Keeping your plants pruned and upright saves space in the garden, and results in much bigger tomatoes when it comes time to harvest.
3. Water Deeply
Watering properly is an essential part of growing healthy tomatoes. Tomatoes can be very touchy when it comes to soil moisture and drainage. I’ve found that, by watering deeply and infrequently, the plants grow stronger and are less problematic.
The idea is to provide a trickle of water over a long period of time, rather than quickly dumping water over the plants. If you use a hose or a watering can, the water is added in a matter of seconds. This provides a superficial watering, only saturating the first few inches of the soil.
The result is a shallow root system that can’t tolerate dry weather. If your plants don’t have a deep root system, they will have less access to nutrients that are found in deeper soil layers.
To water deeply, I recommend watering slowly, using a drip irrigation system. However, this doesn’t have to be a complex system of hoses and spouts! It can be as simple a bucket with a few holes drilled in it, buried a few inches near your plants.
If you have to use a watering can, come back and water 2 or 3 times in the same day to allow more water to penetrate deeply. Then, wait several days or even weeks before watering again. As the topsoil dries out, the roots of your tomatoes will travel deeper in search of the water.
- Water slowly and thoroughly, less frequently
- Add a thick layer of mulch to retain moisture
- Water at the base of the plants, not over the leaves
- Avoid the plants drooping from dry soil (this can lead to blossom end rot)
Without a proper watering regimen, tomato plants will produce non-uniform fruits, and will often have cracked skin. Keep the soil evenly moist, watering deeply and less often, for the biggest, best tomato harvests.
I hope you learned something from this article! Any one of these tips will help your tomato plants grow larger fruits. Next time you harvest a whopper of a tomato, your neighbors will be asking how you did it – whether you share your secrets is up to you.