Plant lovers and environmentally-conscious people are continuously coming up with new, creative ways to promote sustainable wastewater management techniques. Households generate plenty of wastewater from the kitchen, including liquids used for cooking, such as rice water. One common way to repurpose cooking or kitchen wastewater is to use it in the garden.
Rice water is good for plants because it contains numerous essential nutrients for your plants and beneficial microorganisms. However, there are several ways to make rice water, and not all of them can provide equal benefits to your garden.
Further on, we will discuss some essential elements to know about rice water and how some gardeners came to the idea that it can be used on plants. We’ll also be looking into how to use rice water on your plants, along with the practice’s pros and cons.
4 Things to Know About Rice Water Before Using It on Plants
Rice water is a wastewater material common in households where some families cook rice almost every day.
Over a hundred countries consider rice a staple food, and you can only imagine the large volume of rice water generated in each household. This led some families to find alternative ways to reuse it instead of just disposing of it.
But there are a few things to know before you consider getting started.
1. You Can Make It in Different Ways
Rice is found in numerous countries and comes in several varieties. Each variety may require a different method of preparation due to their varying consistency and nutritional contents.
For instance, some people soak rice for several hours to reduce the cooking time required. In other cases, some rice varieties may be sticky due to the different types of starch they contain and thus require a different method of preparation.
As a result, different rice varieties can generate different nutrients and produce varying levels of effectiveness when it comes to plant growth and overall health.
The most important element to keep in mind when thinking about utilizing rice water on plants is that the preparation method matters.
Water From Washing Rice
It is often recommended to rinse rice in cool water to remove dust and dirt. The resulting cloudy rice water, which contains mainly dirt, starch, and a few nutrients, is then flushed down the sink.
One washing is often enough, but some people might find it necessary to do it twice, depending on how dirty the rice looks. However, it helps to remember that rinsing the rice multiple times risks also washing away some essential nutrients.
Washing the rice shortly before cooking and skipping the soaking part will require more water and a longer cooking time. However, even if you don’t soak the rice before cooking, it doesn’t necessarily affect the flavor or texture, especially with some white, long-grained rice varieties. The difference in taste is often subjective.
Many Southeast Asian rice varieties like Jasmine do not require soaking because the excess water will result in a soupy or soggy consistency.
Regardless of whether you plan to soak the rice or not, rinsing is the easiest way to harvest rice water.
Water From Soaking Rice
Some rice varieties, especially colored ones like red, brown, or black rice, often require a soaking time ranging from 30 minutes to several hours. These rice varieties are typically drier and harder, requiring hydration prior to cooking. Otherwise, you will need double or triple the amount of water and time necessary to cook them.
Typically, short-grained and glutinous varieties require a longer soaking time than long-grained rice varieties. A 10-15-minute soaking time is enough for Indian rice like Basmati.
Short-grained Chinese and Japanese rice must be soaked for a maximum of 30 minutes because soaking the rice for longer will remove too much starch, making the cooked rice less sticky.
Moreover, soaking the rice overnight can break down phytic acid, which binds with nutrients like iron, calcium, and zinc, preventing them from being absorbed by the body. This is due to the lack of enzymes in the human body that would otherwise enable us to digest phytates – substances formed from the bonds between phytic acid and essential nutrients.
Water From Cooking Rice
If you’ve been cooking the same type of rice for several years, you probably already know the ideal water-to-rice ratio to achieve the best consistency and texture in your cooked rice.
On the other hand, if you haven’t tried cooking a new rice variety yet, you may need to go through some trial and error to find the best ratio, leaving you with some excess. This excess water typically contains several nutrients that can be beneficial to plants, as long as it is cooled to room temperature before applying.
The heat from cooking the rice can break down some substances through a chemical reaction, releasing nutrients that are different from rice water that comes from rinsing or soaking.
2. It Contains Plenty of Nutrients
Plants have certain nutritional requirements that can change slightly between plant types. Some may absorb more nitrogen, while others use up more phosphorus and potassium.
It can be pretty challenging to determine how much of each kind of nutrient is present in rice water.
The quantity of nutrients depends largely on the following factors:
- Rice variety
- Nutritional qualities of the soil where the rice was grown
- Processing, packaging, and transport method
- Mode of preparation of rice water
Even if you prepare rice water the same way from the same rice variety, there will still be inconsistencies in the nutritional content of the liquid.
Nevertheless, several rice varieties have varying levels of the following essential plant nutrients:
- Nitrogen
- Phosphorus
- Potassium
- Calcium
- Magnesium
- Manganese
- Zinc
- Iron
You would need to send your rice water sample to a laboratory to determine the actual levels of these nutrients in rice water. Of course, that will be costly and impractical.
With that in mind, it is best to treat rice water as a nutritional supplement and not as a complete alternative to fertilizer for plants with specific nutritional requirements, especially during the growing season.
3. Some Parents Feed It to Their Babies
Before arsenic poisoning from rice grains and rice-based products like cereals became a global issue, many parents used to feed their babies rice water. It is considered by many parents to be a suitable first food or drink for babies as it is easy to digest and contains essential compounds.
Although there is little research into these claims, the benefits of feeding rice water to babies can be attributed to the liquid’s nutritional contents – the same reason gardeners use rice water on their plants.
It is important to note that rice water used for feeding babies is prepared from cooking rice. Rice water from rinsing or soaking is unsafe for babies due to the high risk of microbial infection.
Cooked rice water is unlikely to contain harmful microbes because the high heat followed by simmering required to cook rice is enough to eliminate them.
Older research from Singapore also recommended the use of cooked rice water in treating gastroenteritis among infants, especially in areas in developing countries that don’t have access to adequate treatment.
Scientific evidence on the nutritional content and safety of rice water on babies supports the idea that the liquid can be repurposed for other uses, such as gardening.
4. It May Contain Salt or Broth
In addition to the typical plain white rice, there are several flavored rice varieties on the market with spices or flavorings added. Some recipes even recommend replacing water with broth.
You can use regular rice water from rinsing and soaking in your garden, but it’s best to avoid using flavored rice water after cooking. Too much salt is bad for the plants as it may cause dehydration, especially if you plan to use salted rice water on potted plants.
On the other hand, the aroma of the broth may attract insects, microbes, and even house pets to your pots or garden. So if you plan to use rice water on your plants, it’s best to avoid the additives altogether.
To learn more about the impact of salt on plants, you can read my other article: Can Plants Survive if They Get Salt on Them?
How to Use Rice Water on Plants
As discussed, there are several ways to prepare rice water.
Assuming that you’re going to perform all steps from rinsing, soaking, and cooking, you can follow the suggestions below on how to use rice water on your plants:
Rinse the Rice
Using cool water from the tap, fill the rice container with enough water to cover it up to an inch (2.5 cm) above the surface. Stir the rice to remove dirt, but avoid squeezing the grains.
Collect Water in a Separate Container
It’s okay if you want to rinse the rice several times. Just be sure to collect the water in the same container every time you drain the rice.
Pour It Into the Soil
Next, pour the rice water from rinsing into the soil. Be mindful of your plant’s water requirements to avoid overwatering.
Collect Water From Soaking
You can also collect the rice water from soaking. You can use this water on another plant or pour it directly into your garden soil.
Cool Down the Cooked Water
Pour the excess cooked rice water into a container with a lid to prevent microbes and pests from getting to the liquid as it cools down. Wait until the rice water reaches room temperature (approximately 68 °F / 20 °C) before using it on your plants.
A Few Things to Remember
Along with the steps above, keep the following things in mind when watering your plants with rice water:
Avoid Pouring This Water on the Leaves
Letting the starch in the solution sit on the leaves can invite unwanted pests to your plants. Allow the nutrients to seep into the soil to be absorbed by the roots or to feed the helpful microbes.
Pay Attention to Your Plant’s Watering Needs
If you cook rice every day, avoid watering the same plant with rice water as often. Instead, you can use the rice water to feed other plants or pour it on bare garden soil to enrich it.
Alternate Rice and Pure Water
Providing your plant with purified water between rice water feedings can help leach out any excess nutrients from your pot. It can also help rinse your soil of white suds from the rice water.
Benefits: Eco-Friendly, Reduced Risk of Fertilizer Burn
When collected and applied correctly, rice water can be beneficial to plants.
Check out the benefits below:
It Provides an Eco-Friendly Way to Reuse Water
One-time preparation of rice can generate at least a liter (33.8 fl. oz.) of rice water from rinsing, soaking, or cooking. Instead of flushing water down your drain, you can collect it and pour it on your garden soil.
You can use it directly for your gardening needs without having to treat it along with other wastewater sources.
It Doesn’t Cause Fertilizer Burn
The low levels of nutrients in rice water can supplement your plant’s nutrient needs. They are not potent enough to cause fertilizer burn, especially if you follow the recommended frequency of application. Moreover, pouring rice water on the bare ground before planting can enrich your soil.
Downsides: Risk of Attracting Microorganisms and Pests
As with anything in gardening, it also helps to pay attention to the disadvantages of using rice water for plants. It can help you decide whether or not you want to give it a try.
Can Boost the Growth of Harmful Microorganisms
The starch in rice water can feed harmful microorganisms in the soil, compromising the health of your plants. Using rice water can be counterproductive, depending on the type of microbes and the health condition of your plants.
How to Fix
While there is no way to prevent this issue, you can limit the number of times you provide your plants with rice water. If your plant requires weekly watering, you can use rice water every two weeks and feed your plant distilled or purified water in between.
You can also boost your plants’ health through other means, such as providing adequate sunlight and nutrients. This can help them become sturdier and less susceptible to microbial infection.
Dried Starch Suds Can Attract Pests
When you harvest rice water from rinsing, soaking, or cooking, you will notice white suds floating on top. Ideally, you shouldn’t throw them out because they contain starch and other nutrients your plants may need.
However, once the water dries up and leaves behind these white suds, you may notice tiny insects gathering around your plant. You may even find cockroaches because they are attracted to starch.
How to Fix
You can use physical pest repellents like sticky paper to prevent cockroaches and other insects from getting to your plants. Avoid using pesticides because the chemicals may be toxic to your plants. You can also scrape the dried-up white suds on the surface of your soil.
Final Thoughts
Rice water is good for plants as long as you know how to collect it properly. It’s also essential to remember that rice water is not a perfect alternative to fertilizer because it can be challenging to identify and measure the nutrients present in the liquid.
Be sure to follow the tips above on how to use rice water on your plants to maximize its benefits without compromising your plants’ health.
Written by Alexander Picot, Reviewed by Madison Moulton
