Cinnamon is not only a wonderful spice to use in cooking, it also has some interesting benefits when used for plants. If you’re wondering how to use cinnamon for plants, including some of the scientifically proven benefits,^[1]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8433798/ we’ll cover that in this article.

Cinnamon (Cinnamomum zeylanicum L. and Cinnamon cassia L.), is an evergreen tree that grows in tropical regions and is a species of the Lauraceae family. A globally favorite culinary spice, cinnamon is also widely used medicinally, as well as a rich variety of practical applications.

Can Cinnamon Harm Plants?

There is some misinformation when you search this topic where many are saying that cinnamon won’t hurt your plants. However, larger doses, especially of the more concentrated cinnamon leaf essential oil, can actually stunt the germination and growth of plants if too much is used.

However, not to worry because most uses of cinnamon for plants are in doses too small to disrupt plant growth.

In one study, cinnamon oil treatment of seeds was found to reduce the growth of lettuce and parsley. The toxicity was the greatest at 15% or more concentration.

The potential good news is that cinnamon oil may have some beneficial fungicidal benefits for farmers, but more studies are needed. You can read a little more on this under the section below on herbicide benefits of cinnamon.^[2]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8433798/

Cinnamon for Plants – Uses and Benefits

The following cinnamon benefits for plants are based on studies using the plants known scientifically as Cinnamomum zeylanicum and Cinnamon cassia.

Ant Deterrent Benefits of Cinnamon

Ground cinnamon can be a useful deterrent for ants. To apply, simply sprinkle cinnamon around the base of affected plants or across the ants’ known paths. Ants are typically averse to areas where cinnamon is present, making it a natural and non-toxic pest control method.

Antimicrobial Benefits of Cinnamon has Mixed Results

Cinnamon possesses remarkable antimicrobial activity, which is predominantly due to E-cinnamaldehyde.

HOWEVER... research found that while Cinnamon bark essential oil has major potential as antimicrobials, it’s not long lasting as the cinnamon essential oil antibacterial properties are volatile and decompose quickly. So more research is needed to find ways to preserve the potent antimicrobial in the cinnamon essential oil.

Fungicidal Benefits of Ground Cinnamon

Cinnamon possesses potent antimicrobial properties, making it a useful natural fungicide for your plants.

If you identify signs of mold or mildew on your foliage, applying cinnamon to the affected areas can help control and prevent the spread of fungal diseases.^[3]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8433798/

Healing Plant Wounds with Cinnamon

Should your plants suffer any wounds or cuts due to pruning or accidental damage, ground cinnamon can come in handy. Sprinkle some on the wounded area to protect against infections and speed up the plant’s healing process.

The antimicrobial properties of cinnamon may also help to keep the wound clean and free of insects and pathogens.

Herbicide Benefits and Detriments of Cinnamon Oil

Cinnamon oil has been studied to determine if it might be a viable herbicide, especially for commercial crops. Results indicate that it can indeed be a highly effective herbicide against weed seeds, however, cinnamon oil was also proven to adversely impact parsley and lettuce seed germination and plant growth at 15% strength.

So care should be taken when using it in the garden, but the recommended safe dosage of one teaspoon to one quart of water should be safe for plants and soil microbes at .05%

One study found that a 15% concentration of cinnamon essential oil caused a decrease in the number development and growth of lettuce and parsley.

Rooting Hormone Properties of Cinnamon

When propagating a plant through cuttings, cinnamon can be utilized as a rooting hormone. The advantage of using cinnamon powder as a rooting hormone is that it tends to be a fraction of the cost of the commercial rooting hormones.

Cost of Cinnamon Powder vs. Rooting Hormone

Bulk powdered cinnamon on Amazon currently ranges in price from .42¢ – $1.50 (higher price on the organic) whereas commercial rooting hormones tend to range from $3-$23 per oz.

Cinnamon is cheaper than commercial rooting hormone products at an average 96¢/oz for Cinnamon compared to an average $13/oz for rooting hormone.

How to Use Cinnamon as a Rooting Hormone

Dip the cut end of your plant into ground cinnamon prior to planting it in soil. We like to put some of the powdered cinnamon into a small paper or plastic cup so as not to dip it directly into the cinnamon container. Then any excess can be sprinkled around plants or areas of soil that may be susceptible to fungus.

This technique promotes root growth, potentially boosting the success rate of your cuttings. Be sure to cover the entire cut end but avoid using excessive amounts of cinnamon.

Seedlings Protection Using Cinnamon

To shield your seedlings from common fungal diseases such as damping off, try sprinkling a bit of cinnamon on the soil surface around your young plants. This organic method can prevent disease from establishing itself on vulnerable new growth.

Soil – How Cinnamon may Improve Soil

Cinnamon is thought to enrich soil nutrients and deter certain types of plant pests. By adding it to your soil, you may create a healthier environment for your plants to thrive. However, moderation is key to prevent potential negative impacts on soil pH and beneficial microbes.

Mosquito Larvae – Cinnamon has Proven Impact

Cinnamon leaf oil has proved to be very effective as a killing agent for mosquito larvae. The compounds in cinnamon leaf oil: cinnamaldehyde, cinnamyl acetate, eugenol, and anethole, were found to be the most effective against mosquito larvae.

So while mosquito control may not be the primary benefit of cinnamon, when you use cinnamon for plants in the yard and garden, it can help reduce the mosquito population as a secondary benefit.^[4]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8433798/

In scientific research, cinnamon was found to exterminate mosquito larvae.

~Study on Cinnamon as a Useful Preventive Substance for the Care of Human and Plant Health^[5]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8433798/

Reference

Kowalska J, Tyburski J, Matysiak K, Jakubowska M, Łukaszyk J, Krzymińska J. Cinnamon as a Useful Preventive Substance for the Care of Human and Plant Health. Molecules. 2021 Aug 31;26(17):5299. doi: 10.3390/molecules26175299. PMID: 34500731; PMCID: PMC8433798.^[6]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8433798/

Different Forms of Cinnamon for Plant Use

While ground cinnamon is the most commonly used form for plant care due to its ease of application, you can also use cinnamon oil or cinnamon sticks.

Cinnamon oil is highly concentrated and should be diluted before application. It can be used in a spray form for a wider reach or to target specific pests. Cinnamon sticks, on the other hand, can be utilized as a slow-release form of cinnamon in potting soils or placed around the garden to deter pests.

Different Forms of Cinnamon for Plants

In caring for your plants, cinnamon can be utilized in a variety of forms:

• Ground Cinnamon: The most commonly used form for plant care, ground cinnamon is easy to apply directly to the soil or onto the plant itself. This form is versatile and can serve multiple purposes, from acting as a natural fungicide to promoting root growth.
• Cinnamon Oil: More concentrated than its ground counterpart, cinnamon oil should be diluted before use. Once diluted, it can be sprayed onto plants to target specific pests or diseases.
  • Spray: Cinnamon in a spray form, can also be effective, but it’s crucial to remember to dilute the oil properly. Cinnamon oil is very concentrated and can harm plants if applied in its pure form.
  • Cinnamon Spray Ratio is about 1 teaspoon of cinnamon oil to 1 quart of water. This mixture can be sprayed directly on affected plant parts. As always, it’s a good idea to test a small area first to ensure the plant doesn’t have an adverse reaction to the cinnamon spray.
• Cinnamon Sticks: These can serve as a slow-release form of cinnamon in potting soils or when placed around the garden. They gradually break down and infuse the soil with cinnamon’s beneficial properties. Also, their presence can help deter certain pests, just as ground cinnamon would.

These benefits make cinnamon a handy tool for organic gardening. However, like any other tool, it should be used in moderation. Excessive use of cinnamon may harm beneficial soil microbes or alter soil pH. It’s also worth noting that while cinnamon can deter or control certain pests and diseases, it won’t eliminate severe infestations or infections. Always consider the overall health of your plants and consult a professional when needed.

So How Much Cinnamon is Safe for Plants?

For ground cinnamon, a light dusting on the soil or plant surfaces is typically sufficient for most applications. Excessive application may negatively affect beneficial soil microbes.

If you’re using a cinnamon oil spray, it’s important to dilute it properly – a common ratio is one teaspoon of cinnamon oil to one quart of water.

Avoid over-spraying as it can potentially cause damage to plant tissues. It’s recommended to always test a small area first to ensure the plant doesn’t have an adverse reaction. Using cinnamon sparingly and only as needed can offer the beneficial properties you’re seeking without putting your plants at risk.

How to Apply Cinnamon for Plants

Applying ground cinnamon to plants and soil effectively does indeed require some care. Here are some best practices for using both cinnamon powder and cinnamon oil:

Ground Cinnamon

1. Target the Soil: If you’re using cinnamon as a fungicide or deterrent for pests that live in the soil, it’s best to apply it directly to the soil. For this you can use ground cinnamon where it can also protect seedlings from diseases like damping off. A light sprinkling is critical as too much cinnamon can actually kill plants and helpful microbes.
2. Avoid Wind: Ground cinnamon can easily blow away in the wind. So, try to apply it on calm days or in protected areas where wind isn’t an issue. Alternately, you can apply ground cinnamon or cinnamon oil as a spray shaken on water with a few drops of castile soap to help it stick to the affected areas
3. Moisten the Area: It can also help to moisten the area slightly first. The dampness can help the cinnamon stick to the plant and remain in place long enough to have an effect.

Cinnamon Oil

1. Dilute Properly: Cinnamon oil is very concentrated and can harm plants if not properly diluted. A common ratio is one teaspoon of cinnamon oil to one quart of water.
   • 1 tsp. cinnamon oil
   • 1 qt. water
2. Spray: A diluted cinnamon oil solution is typically applied as a spray. This can be applied directly to the parts of the plant affected by fungus or pests. As with any new treatment, it’s a good idea to test it on a small area first to see how the plant reacts.
3. Even Application: Using a spray bottle allows for an even application and can also reach areas of the plant that may be hard to treat with powder. Be sure to spray both the top and undersides of leaves where pests or disease may be present.

In terms of which parts of the cinnamon plant are used, typically the bark is the part that is used for both culinary and gardening purposes. This is where the compound cinnamaldehyde, which gives cinnamon its flavor, scent, and beneficial properties, is found. The oil is also extracted from the bark. Cinnamon leaves and roots have some uses in traditional medicine, but for the purposes of plant care, it’s the bark — ground into a powder or distilled into oil — that’s typically used.