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Rice Water for Plants – Facts, Benefits, and Disadvantages

As a gardener, I am always looking for ways to reduce waste that also improve the quality of my crops. Further, I love finding ways to save money with do-it-yourself gardening solutions. That’s why I was so intrigued when a friend told me I could use leftover rice water for plants as a fertilizer and pesticide.

I normally just dump rice water down the drain, so I decided to do some research and see if I should start watering my garden with rice water. I was excited by the idea of not needing to purchase as much fertilizer and saving a little money. And increasing crop production at the same time!

They also told me that if I ferment the rice water, it works as an excellent pesticide and promotes healthy bacteria growth in the garden. So, I needed to figure out what the fuss about rice water is all about!

The Benefits of Rice Water for Plants

Rice water contains a lot of nutrients that can help your plants grow.

There are countless anecdotes that watering your garden and indoor plants with rice water will stimulate increased plant growth and plenty of blogs are hyping the benefits of rice water.

A growing body of scientific work indicates that this is true – rice water contains many of the nutrients plants need to grow! Studies have found that rice water for plants increased the growth of many varieties, including tomatoes, lettuce, mushrooms, peppers, and garlic.

It isn’t just a gardening myth!

The Nutrients In Rice Water

First, rice water for plants contains the three most important and essential nutrients for a complete fertilizer – nitrogen, phosphorous, and potassium. Rice water also includes important nutrients for healthy growth such as magnesium, calcium, iron, and sulfur. Sulfur is understood to promote thiamin (Vitamin B1) synthesis and thiamin helps plants fend off disease.

Rice water also contains many B vitamins that are critical for plant health and growth. Overall, rice water has been found to have comparable nutrient contents as standard inorganic fertilizers. This makes it a great organic fertilizer you can make yourself, at home.

Additionally, rice water contains starch, which plays an important role in feeding the bacterial and fungal environment of your garden. The starch not only promotes plant growth, but it is an important energy source for healthful bacteria and important fungi that your garden relies on for its well-being.

Washed Rice Water vs Boiled Rice Water

There are two ways people typically make rice water.

  1. First, many people like to wash their uncooked rice before they cook it. This is an optional step in preparing rice. The leftover water may be used to water your garden as rice water for plants.
  2. Alternatively, you can use the leftover water from boiling rice. Boiled rice water is richer in nutrients than washed rice water. This is because the boiling process extracts more of the nutrients from the rice, whereas washing typically only extracts nutrients from the bran and hull of the rice.

The Disadvantages of Rice Water for Plants

It turns out, however, that there are some potential issues that may arise from watering your garden with rice water for plants.

  1. While starch can promote the growth of healthful bacteria, starches in rice water can also feed unwanted bacteria that may harm your crops.
  2. Additionally, the starches can attract pests that may, as a result, eat or damage your plants.
  3. Finally, too much starch in your garden can lead to root rot

Fermented Rice Water for Plants

Fermented rice water

The potential downsides of using rice water can be addressed by fermenting the rice water before applying it to your garden.

Scientific work by Nabayi and colleagues has found that fermenting rice water can significantly increase the beneficial impacts of using rice water for plants as a fertilizer. Further, the fermentation process promotes the growth of beneficial bacteria while also killing back harmful bacteria. Great benefits for plants in your garden!

Specifically, you can ferment rice water to promote lactobacillus bacteria growth. Lactobacilli play a critical role in human health, as it kills many of the pathogens that are harmful to humans. That’s why it is healthy to eat Lacto-fermented foods such as yogurt, kimchi, and sauerkraut.

Thus, it is best to use fermented rice water to fertilize your garden and to promote healthy plant growth. 

How to Make Fermented Rice Water

The next step, then, is to figure out how to make fermented rice water for plants. The good news is that it is super easy! The resulting product can be used in the garden and for your potted plants – for almost any type of plant.

The first step in the process is making your rice water. You can either make washed uncooked rice water or boiled rice water.

How to Make Washed Rice Water

This method is quite straightforward.

  1. Place your rice in a bowl.
  2. Fill the bowl with water.
  3. After about thirty minutes, the water should take on a milky opacity.
  4. Pour this water off and you have rice water for plants.

How to Make Boiled Rice Water

Depending on how you make your rice, you may already make excess boiled rice water. I usually put just enough water in my rice so that there is no water at the end.

To make excess boiled rice water, simply double the amount of water you use to make your rice. When the rice is done, pour off your excess rice water for fermentation.

How to Ferment Your Rice Water

Now that you have your rice water, the next step is to ferment it. Once again, this step is quite simple. The simplest method, which is what Healthline recommends if you’re making it for your skin or hair, is the following:

  1. Put your rice water in a jar.
  2. Leave the jar at room temperature for up to two days.
  3. Smell it regularly. Once it starts to smell sour, it’s ready to use.
  4. Store it in the fridge and dilute it prior to using it as rice water for plants.

The second method is a little more involved but still easy as pie. All you need is a jar, some sugar, and a little bit of milk.

  1. Fill your jar between 50-75% full with rice water. It is important that there is some air in the jar to promote the fermentation process.
  2. Add 1 teaspoon of sugar and 4 tablespoons of milk to the jar.
  3. You can cover the jar, but do not completely seal it to ensure some airflow into the jar.
  4. Let the jar sit for around three to five days. At this point, the mixture should transition from opaque to translucent in appearance.
  5. You are now ready to water your garden with fermented rice water!

Other Uses for Fermented Rice Water

Fermented rice water isn’t just useful in the garden. It sports a host of other benefits, too. Some of those research-backed benefits are outlined below.

How to Use Rice Water In Your Garden

rice water in a watering can for watering the garden and plants

Whether or not you have fermented your rice water, you can top-water your garden with it. Non-fermented rice water should be used only as a supplement to standard watering.

While there are no clear scientific guidelines for the exact amount and consistency, some argue that unfermented rice water should only be used to water your garden once every week or two. If you over-water your garden with unfermented rice water, you will potentially promote unwanted bacterial growth and root rot. 

It is important that you monitor the health of your plants as you provide them with rice water and stop using rice water if you notice undesirable outcomes.

Fermented rice water can be used more consistently, given its anti-microbial properties. The fermented mixture can be a bit potent, so it can be mixed with additional water to dilute it and ensure you can water your whole garden with it.

Like with unfermented rice water, it is important to monitor your garden as you administer the fermented rice water. 

Final Thoughts

Rice is one of the most commonly eaten grains in the world. Thus, discarded rice water represents a large source of waste globally. Using rice water to water your garden will not only help with the overall growth of your plants but helps reduce water waste overall.

Fermenting the rice water can also help promote healthy bacterial growth, ensuring the vitality of your garden. This can help you save money that you would’ve otherwise spent on commercial fertilizer and pesticides.

All you need is some rice and water and you can introduce this useful and practical fertilizer to your garden!

Thanks so much for reading! Don’t miss our other articles on gardening, soil, and fermenting:

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