Cooked rice water is really good for plants.
The cooked rice water acts as a natural fertilizer to the plants and provides the plants with needed nutrients like potassium, phosphorus and nitrogen.
Cooked rice water also adds starches and beneficial microbes to boost the health of the soil that the plant is in as well as boosting root growth of the plant.
Using cooked rice water on your plants can lead to healthier and lusher plants, although it should be used in moderation and diluted as using too much rice water and not diluting the rice water could result in nutrient buildup and attract insects and other pests.
I use cooked rice water extra nutrients to my indoor plants and outdoor plants as well including ferns and succulents.
I even use the cooked rice water on tomato plants, pepper plants and okra plants in my garden outside and it helps them thrive.
Although the plants you should be cautious about using rice water on are plants that are housed in aquaponic systems as the rice water may disrupt or block necessary functions in aquaponic systems.
You can also use rice water to add to soups, knead dough with the rice water, cook porridge or oats with rice water, boil vegetables in rice water, grind chutneys with rice water and make a soothing rice Kanji with the rice water.
Rice water is often discarded after use, although rice water is beneficial for a lot of things including cooking with in other foods and adding to plants.