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How To Prune Tomato Plants – And Why It’s The Secret To A Great Crop!

Believe it or not, one of the most important chores you can perform to ensure success for your tomato plants is to prune them!

It not only makes a huge difference in a tomato plant’s overall health, but also spurs on a more productive crop.

In fact, there are a whole host of benefits for pruning. Like better circulation, less disease, increased pollination and higher yields. Even better, it makes plants easier to maintain with weeding, watering and fertilizing chores.

Check Out Our Podcast On How To Grow The Best Tomatoes On The Block!

But perhaps best of all – it is one of the easiest garden chores you will ever perform! Here is a look at how to prune your tomato plants this year to help grow your best crop ever.

We also have included below our video tutorial on pruning as well.

How To Prune Tomatoes

Create Space At The Bottom Of Plants

Much of the rot and disease that affect tomato plants comes from the soil. Soil borne diseases such as tomato blight are caused from spores living in the dirt below.

pruning tomato plants
Pruning helps provide valuable circulation and light to tomato plants.

These spores are easily transmitted to plants when they splash up on the lower leaves of plants. Especially when it rains or when plants are watered.

But by clearing out the lower branches and foliage, you reduce the chance of infection and spread. In addition, that open space created from pruning gives plants improved air circulation. And added air is critical for growth, pollination – and keeping mildew at bay too!

How To Prune The Bottom Areas Of Tomato Plants

How much to prune up from the bottom depends on what type of tomato plant you are growing. (See Determinate vs. Indeterminate Tomatoes)

Determinate varieties tend to grow short and bushy. For these smaller style plants, prune up so that there is about 8 to 10 inches of open space near the bottom.

Prune Tomato Plants Gradually

Do this gradually as the plant grows through the season. Start by removing the first few branches early on. As the plant continues to grow and fill out, you can continue to prune up to get to the full height of open space.

Prune the bottom of plants gradually as the plant grows. Here, our San Marzano at just 6 weeks is pruned up about 3 to 4 inches. We will gradually prune it to around 12".
One of our San Marzano tomato plants growing early in the season last year.

For large, indeterminate varieties like Brandywine, Black Krim, etc., more space should be cleared. For the larger tomato plant varieties in our garden, we prune up anywhere from 12 to 18 inches.

The space created by trimming this lower level of branches allows for excellent air circulation and light to the plants. That air flow and light do wonders to keep mold and disease in check.

But it also makes it hard for crawling ground insects and pests to get an easy lift up to your plants. As an added benefit, it also give you easy access to the root zones of our plants for watering and fertilizing. (See : How To Fertilize Garden Plants For Success)

compost tea on tomatoes
Having open space at the bottom of plants makes watering and fertilizing easy.

Once space at the bottom is cleared out, be sure to apply a good 2 to 4″ layer of straw or shredded leaf mulch.

Not only will it help to prevent weeds, it keeps the soil moisture and temperature regulated. It will also help keep those soil borne disease spores from splashing up to the higher limbs.

Pruning The Middle & Tops Of Tomato Plants

In addition to the lower sections of tomato plants, it is also important to clear space from the middle and tops of plants.

We always prune back any “wild branches” from our tomato plants that cross over into paths. We also clear out a few middle branches to let light and air into the mid-section of the plant.

If plants have too much foliage (like above) in the middle, it cuts down on circulation and light. That leads to longer ripening times and less fruit.

We tend to choose the branches with little to no flowers on them. This way, the more productive branches that remain can continue to develop their fruit.

Do not overthink or over-prune at this point. Simply remove a few branches and stems to allow a bit of light in.

Prune Out Disease & Damage

At all times, stay on the lookout for any branches or leaves that may show signs of black spot or mold. Remove these branches immediately to help stop any disease from spreading from plant to plant.

prune tomato plants
Always remove dead or damaged branches quickly from the plant.

When pruning suspicious or damaged leaves and stems, be sure to keep them out of your compost bin to avoid passing the disease on.

How & When To Prune The Tops Of Tomato Plants

Our last bit of pruning usually comes in mid to late summer. At this point, many of our tomato plants begin to grow too tall for our supports. We simply top off the plants to keep them manageable.

How To Prune Tomatoes – Video Tutorial

It allows the plant to direct it’s resources to ripening fruit, and not growing more foliage. It also makes harvesting much easier, and prevents splitting and cracking of branches that become too heavy to support.

What About Suckers

So what about the suckers on tomato plants? Well, many folks still remove these, and it certainly does not harm the plants to do so.

We used to do this as well, but stopped after years of experimenting in our garden showed us it simply does not affect our crop yields or plant health.

How To Prune Tomato Plants – A Few Final Hints & Tricks

Always be sure to use a sharp pair of hand pruners or heavy-duty garden scissors. Dull blades will tear the plants, causing damage and stress. Be sure when finished to wipe down or wash the blades to keep any contamination at bay. (Product Link : Fiskars Hand Pruners)  

how to prune tomatoes
Always use sharp pruners or scissors when pruning.

In addition, it’s best to prune tomatoes early in the morning or late evening. Plants are at their highest stress level during mid-day sun, so avoid this time entirely.

Happy Pruning, And Gardening! – Jim and Mary

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