Why do tomato plants have hairs? What you never knew!

Tomato plants feature minuscule outgrowths known as trichomes, or hair. The word “trichome” is derived from the Greek term “trichomes,” meaning hair. These tiny projections extend from the tomato’s surface. Usually, these structures are found on the stems and leaves of the tomato, reaching a length of a few centimeters.

The tomato plant hair or the trichome is the natural defense system of tomato plants; just like humans, our immune system is our defense system. These tiny trichomes also secrete essential oils, giving tomato plants a wonderful scent.

Generally, trichomes are unicellular or multicellular; however, they are multicellular epidermal cells resembling hair in TOMATOES. These organs are meant to protect the plant against harm from weather and animals.

Types of trichomes

There are two types of trichomes: Glandular and Non-glandular.

2 red ripe tomatoes

Non-glandular trichomes

Non-glandular trichomes are like feelers, and they come to a point. They can sense when an insect or herbivore walks by or on the plant’s surface. Once they perceive, a message is sent to the plant to activate its defense mechanism against herbivore attack.

Additionally, these trichomes protect the plant from damage by rainwater by keeping it off the leaf surface. They allow the water to roll off the leaf surface without touching the delicate dermal cells underneath.

Glandular trichomes

Glandular trichomes are similar to non-glandular, and they come to a point and beyond. You will see a rounded gland resembling a dewdrop at the tip of these trichomes. Glandular trichomes can also sense when an animal walks on the plant surface or nearby.

When this happens, the gland at the tip raptures, letting out a mixture of alkaloids, acyl sugars, terpenes, and other defense-like proteins. The fluid works by putting off herbivores through small, and it can also be toxic to insects. The liquid from tomato trichomes may also trap the insect, causing it to stick to the plant.

In summary, the non-glandular trichomes provide a physical barrier from biotic and abiotic stressors. The glandular trichomes, on the other hand, produce a rich repertoire of secondary metabolites.


Studies suggest that TOMATO HAIRS density is due to genetic factors and environmental conditions. These features are dependent on several genes.

The wooly gene (Wo) makes the trichomes on the tomato plant surface appear angora-like or fuzzy; it also brings about more and longer trichomes.

Secondly, we have another partially dominant gene- the Hirsute (Hr). It causes the upper surface of tomato leaves to bear more long trichomes. The Hr gene also causes the plant to bear fruit with trichomes on the surface. This gene type is more common in wild tomato varieties.

Finally, we have the third gene type, the hairless (hl), which suppresses trichomes’ growth. It, however, causes the surface of the leaves to appear curled or gnarled. Without these protective TOMATO HAIRS, the leaf surface is left vulnerable and brittle. As a result, the leaf surface cracks easily, becoming susceptible to infections.


The purpose of tomato trichomes is dependent on their location. Some are above, and others beneath the ground.

Tomato hair helps the absorption of water and nutrients.

When buried in the ground, TOMATO HAIRS develop into roots that help absorb water and nutrients, boosting the plant’s health. It also improves the plant’s chances of survival and yield. For this reason, you are advised to plant TOMATOES with only one-third of the plant above the surface. As we will see later, this feature could be an adaptation for survival.

Trichomes harden the tomato plant skin.

tomato plant hairs

Tomato hair makes the skin of the leaves and stems tougher by adding another layer. As a result, the fragile plant is safer from injury by animals and other plants that brush against it. It becomes more difficult for pests that feed on plant juices to penetrate the stem and leaves with this extra layer.

Moreover, tomato plants have weak and wobbly stems. Without this extra layer of epidermal cells, tomato stem and leaves would hardly survive certain weather conditions, such as wind and heavy downpours.

Tomato hair helps repel herbivores.

As we saw above, TOMATO HAIRS produces an oily substance that works for plant protection. This substance originating from a particular type of trichrome is meant to protect against predation.

It is sticky, and insects that land on the plant can get trapped, thus stopping them from feeding on the tomato plant or leaves. Suppose you have ever touched the surface of a tomato plant or leaves during gardening. In that case, you can attest to the yellowish-colored substance stuck on the hands.

The compound also produces a specific type of unpleasant smell. The plant uses the scent to put off predators from taking a bite. As we saw above, tomato plants can sense predators or other animals passing by, producing this compound.

Finally, the TOMATO HAIRS deter animals from eating the plants. This is because the hairy appearance of the surface puts off animals. As a result, not many herbivores eat tomato plants and other plants with trichomes.

Tomato hair prevents attack by diseases.

Tomato plants are susceptible to insect, viral, bacterial, and fungal attacks that destroy the plant and reduce yield. The oily substance produced by TOMATOES also prevents certain harmful organisms, such as broad mites, from laying eggs and multiplying on the leaf surface.

It also deters the formation of caterpillars that destroy plants and simultaneously impedes these caterpillars from searching for food in the plant.

Studies show that tomato trichomes also prevent the tomato from viruses and other disease attacks. The oily compound tomato trichomes produce is antibacterial, antiviral, and antifungal. However, even with its secretion, diseases still affect tomato plants. Overall, it would be impossible for the plant to survive without producing these oils.

Additionally, the oil keeps the leaf surface moist, preventing hardening and cracking, injuries that would pave the way for entering disease-causing organisms into the plant system.

Another way the plant can keep off virus and bacteria attacks is by preventing certain insects that transfer illnesses, such as whiteflies, from landing on its surface. Whiteflies cause many tomato diseases and are a significant menace to farmers and gardeners. And this article covers dealing with whiteflies.

Other researchers suggest that animals and insects that feed on tomato plants get poisoned by the oils released by the trichomes. Insects, conversely, have s system of sensing poisonous plants to avoid them. For this reason, tomato leaves and stems are toxic to animals and humans.

Tomato hairs not only help from attacks of diseases, but sometimes they do suffer from them. In the video below, I show you what tomato diseases they suffer from and how to deal with them.

Tomato hair help in temperature regulation

Trichomes in tomato plants are also helpful in regulating temperatures within the plant during hot and cold seasons. The plant trichomes protect it from extreme temperatures that would cause damage.

During hot seasons, these features prevent excess heat from reaching the leaf surface, keeping it cool. TOMATO HAIRS also provide a larger surface area for the plant to lose heat to the environment cooling down.

In cold weather, the same features help keep the plant alive when frost threatens in the spring or fall. They do so by acting as insulation and preventing the leaf surface from the effects of cold weather. However, trichomes cannot offer enough protection when the temperatures become extreme and the plant dies.

TOMATO HAIRS trap water within them, preventing the moisture from escaping to the immediate environment. This water helps cool the plant leaves during hot weather, giving them a more conducive internal environment.

The humidity levels in the atmosphere also determine the amount of water the plant loses through transpiration. With high humidity, less water is lost. However, the plant will likely lose more water if the humidity is low. This is when trichomes become most beneficial to the tomato plant.

I recently wrote an article on how temperatures affect tomato plants; if unsure, check it out.

Tomato hair offers resistance to drought.

During dry seasons, tomato trichomes help keep the plant alive in various ways. First, the non-glandular trichomes under the ground develop into a more extensive root system, which allows the plant to absorb more moisture sustaining the plant’s survival.

This feature enables the plant to beat drought by preventing moisture loss through the leaves via evaporation in hot and sunny weather. These roots are less resistant to underground conditions. As a result, their die-off is very fast, becoming lignified and unable to function. However, as they die off, new cells start forming.

Also, during hot weather, the oil produced by TOMATO HAIRS keeps the leaf’s surface and stem moist and covered by direct sun and wind that dry up moisture. For this reason, they prolong the plant’s life during dry and hot seasons.

Moisture escaping from the leaf surface is also trapped in the TOMATO HAIRS preventing it from escaping to the environment. These hairs reduce the rate at which water evaporates from the leaf surface through transpiration.

Tomato hair helps regulates light absorption.

Studies show a need for plants to regulate the amount of light they absorb, just like water, air, and minerals. Tomato plants are affected by ultraviolet sun rays. For instance, the exposure of tomato fruit to intense sunlight causes sunscalds. However, the hairy surface helps them keep these harmful rays from reaching the leaf and stem surface.

TOMATOES, like other plants, need light to manufacture food through photosynthesis. Trichomes also help in photosynthesis; even with low light, these TOMATO HAIRS create a large surface area for trapping light.

Researchers have confirmed that tomato trichomes can synthesize and store foods for plants. Additionally, these plant organs secrete large amounts of different specialized metabolites. This means that despite being made of epidermal cells, they have structure and function like the plant leaves.

Protecting Tomato Trichomes during gardening

Since we are now aware of the function of tomato trichomes, you should be careful when handling tomato plants during gardening. Tomato plants can heal from minor damages; however, before recovering, the areas of injury act as entry points for viruses and other disease-causing organisms, which are likely to affect plant development and productivity. You should, therefore, avoid touching your tomato plants unless it is essential.

It’s crazy how many diseases tomatoes can suffer from, so I wrote a dedicated article on 13 of the most prevalent diseases and how to prevent them.

Conclusion on Why do tomato plants have hairs?

Different types of trichome cells perform various biological functions in the tomato plant. Not only do trichomes guard the plant against attack but also from other conditions such as damage by heat and cold. Trichomes increase the TOMATO plant’s resistance to drought and ultraviolet sunlight. The amount of trichomes on the plant surface directly affects the amount of heat reaching the leaf surface.

TOMATO HAIRS, therefore, affect not only the plant temperatures but also the rates of photosynthesis (production of energy) and transpiration (water loss through the plant leaves).

Additionally, trichomes help regulate the tomato plant’s internal environment by controlling the plant’s water levels. Excess water absorption can be damaging to the plant. Whenever the plant absorbs excess water from the soil, these glandular trichomes release it faster through their glands.

Tomatoes are great to grow, especially if you follow the basic rules and methods. I wrote a detailed article on growing tomatoes at home to ensure perfect results every time. Read that here.

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