When to top tomato plants is often within the minds of gardeners who plant indeterminate tomatoes of the Solanaceae family. It is because they do not have a specific growth height and use a lot of energy to grow to ridiculously tall heights.

When To Top Tomato Plants

It can affect their fruit production, leading to reduced and slow ripening of the yields. Keep reading because in this article, will discuss the best time for topping this plant and the benefits of doing so.

When Is the Time To Top Tomato Plants?

💥 The time to top the tomato plants are before the frost begins, and after the plant has achieved six feet in the cold zones. In addition, you should also top it when the humidity in the greenhouse has become too high, during pre-planting, and in the early season.


Top your tomato plants when they achieve the height you find ideal. Sometimes, these plants can overgrow, although this quality is not found in determinate tomatoes. Topping means abundant harvest, but timing is crucial to this important practice.

– Before Frost Begins

Consider pruning or topping your plants during the late season, when the blooming has been done already in a proper way, this is because it is the time before frost begins. During this season, your plants are so vibrant and full of life, and if they had not been affected by diseases such as leaf spot and blight, they often carry many unripe fruits.

The best time for tomato pruning is four to six weeks before the frost begins, to consider how the plant has been established and developed already. For instance, cordon tomatoes continue flowering and bearing fruit, topping slows down the process, and now, the plant converts the energy it uses to produce flowers to ripen the fruits.

Before Frost Begins

In addition, the immature fruits also get ready for harvesting so that they ripen fast when taken indoors without compromising their taste.

If you have planted yours in a greenhouse, check the plants’ foliage for withering. In this case, if it has started withering, close the windows and other openings to ensure the warmth remains inside. This warmth will ripen the fruits, and those that fail to get ripe in the greenhouse do not take long after when you store them indoors.

– After Achieving Six Feet in Cool Zones

Hardiness zones six and below are considered cold areas with an average temperature between -10 and zero degrees Fahrenheit. Gardeners in such areas cannot afford to underutilize any beam of sunlight that appear.

If you consider tall growing plants, the indeterminate varieties can grow past six feet tall, but in hardiness zones six and below, it means slower growth. The simple reason behind this is that the plant’s foliage blocks the sunlight from reaching the lower parts.

As a result, the process of photosynthesis is then affected, causing the fruits to ripen at an annoyingly slow rate. Topping the plant before reaching six feet helps to prevent shadowing the lower part of the plant and promotes the ripening process.

– When the Humidity in the Greenhouse is Too High

Growing tomatoes in a greenhouse require a great deal of balancing humidity levels, temperature, and lighting. Because the plant thrives in relatively warm temperatures, gardeners prefer planting it as their commercial horticultural plant of choice.

These plants grow perfectly in greenhouses with humidity levels between 65 and 75 percent at nighttime and when it is between 80 and 90 percent in the daytime. The difference can be explained as a result of higher temperatures during the day than the night, which increases evaporation.

On another note when the nighttime humidity goes beyond 75 percent, it is considered excess and this is the time that you have to keep some things in mind.

The excess humidity causes nutritional deficiency, where the plant is unable to absorb enough calcium, and in this case, it would also increase the chance of attack by rot and mildew on the plant, hence, topping is a great choice to avoid this damage.

When the Humidity in the Greenhouse is Too High

Top tomato plants to grow to their full potential in the greenhouse set-up. By topping, you reduce the amount of shade and allow even distribution of temperature to the plant. Due to this reason the temperature will go up, the humidity level goes down, allowing it to absorb the nutrients properly and produce healthy fruits.

– Pre-planting

Topping tomato plants when planting applies to those that have been pre-planted in a nursery and professionally wrapped for sale. Sometimes, the young plants will have started producing flowers indicating they are ready to produce fruit, hence before they get planted, you can cut the flowers.

To elaborate further, when transferring them to your garden, ensure you get rid of the flowers to allow the plant to have fuller foliage for potentially higher vegetation. Use the tomato pruning guide provided on the wrapper to ensure you do not bruise your plant when removing the flowers.

– During the Early Season

Once you put your plant in the garden or pots, which is when using hanging gardens, it begins to produce leafy suckers. Consider topping tomato plants in pots and your garden by removing these suckers.

It is because they slow down the fruit development of your plants since they have to feed. Keep pruning them until the plant reaches 12 to 18 inches in height. This approach is excellent for gardeners living in cold areas. You achieve maximum efficiency when you remove all the suckers from your plants.

During the Early Season

However, a different approach to completely removing the suckers works better if you live in warmer climates. Because there is plenty of warmth and sunlight, pinching these suckers works best.

Basically what happens is that it prevents the suckers from flowering while giving the plant fuller foliage. The foliage becomes handy after the fruits have been produced by providing shade that protects them from sunburns.

What Happens If Tomato Plants Exceed the Right Height?

If the tomato plants exceed the right height you should top or prune them, and make sure that you would keep doing so. You should also remove their flowers and cultivate the fruit as well, and when you see the leaves weakening, cut those too.

– Proper Pruning

A genius tip is knowing when to stop tomato plants growing. It is because, past 18 inches, the plant starts focusing on feeding the foliage and not on fruit development. If your plants have overgrown, you can prune them as well.

It helps in preventing it from reaching extremely high heights, because cutting the top allows it to grow more foliage, which means more fruits.

Proper Pruning

If you don’t know how to trim tomato plants to produce more fruit, look for new suckers on the plant. These take the extra energy from your plant, making it produce few and small fruits.

Consider removing them to allow the produced flowers to grow into sizeable fruits. Cut them from the point where they meet the stem using sharp shears while being careful not to damage the plant. And because other suckers will grow back, keep cutting them off.

Additionally, be keen on the dried-out foliage when pruning your plant. Ensure you remove all these parts to allow more light to get in. Damaged branches are also not good for your plant, and you should cut them off as well.


Topping tomatoes has specific timing to ensure gardeners enjoy the best results for their plants. Here is a summary about topping this plant and what we covered in this article:

  • High humidity levels affect the plant’s ability to take important nutrients that are essential for growth and development.
  • Plants grown in pots can also benefit from topping, because it encourages their growth.
  • Removing flowers when planting your young tomato varieties from the wrapper to the garden is highly recommended. It prevents the plant from producing fruits early.
  • Topping should happen four to six weeks before frost begins, or when the humidity is too much in the greenhouse.

Are you a gardening enthusiast dealing with the nagging question of when to top tomato plants? Now that you have read the article, you can choose the best time to top your plants to enjoy large fruits and a bountiful harvest. But do not do it on the determinate variety as these are not continuous growers and die after their first production of fruit.


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