Table of Contents
- 1 What are rice hulls?
- 2 What is the purpose of mixing rice hulls with garden soil?
- 3 How to Use Rice Hulls in Gardening
- 4 Comparison of Rice Hull with Other Soil Amendments
- 5 FAQ
- 6 Conclusion
- 7 References
What are rice hulls?
Rice hulls, also known as rice husks, are the by-products of rice. You may also know them as the seed coat or protective covering of rice grain.
But did you know you can use rice hulls for gardening?
Rice hulls are excellent soil amendment because they improve soil drainage and moisture-holding capacity.
Further, rice hulls provide good aeration to any grow medium 
Rice hulls are also used as a hydroponic media to improve plants’ growth.
Unlike perlite, rice hulls do not require mining or any manufacturing processes.
Rice hulls do not cause any harm to the environment (unlike peat moss) and are a very sustainable material for gardening.
Whereas peat moss takes thousands of years to form, and that’s why it is not environmentally friendly.
First, the millers remove the hulls from the rice grains and then parboil to sterilize the materials at a higher heat.
This temperature ensures the destruction of diseases and weed seeds. Rice husks are regarded as non-toxic and organic amendments.
Furthermore, they break down easily, and due to their stability, they last for a longer duration.
This sustainable soil amendment is very cheap because it is considered a kind of waste. Hence, gardeners can easily buy them from rice mills.
Related post: Various Types of Hydroponic Growing Medium
What is the purpose of mixing rice hulls with garden soil?
Rice husks are biodegradable, and they improve soil physical and chemical properties.
Hence, it would be best if you mixed them properly in your garden.
Due to its availability, many farmers and gardeners use it on farms or potting soils.
Mixing rice hulls with gardens or using it as the hydroponic growing medium reduces the need for peat moss and other expensive amendments.
Rice hulls are rich in silica (94% of the weight) . Silica improves the drought tolerance limit of the plants by delaying the wilting point.
Also, it enhances the stability of the stem and helps the plant resist the toxic effects of micronutrients. 
In addition to this, rice hulls can increase the aeration capacity of the soil and reduce the risk of soil compaction.
Moreover, you can also use these materials as mulches to cover the surface.
How to Use Rice Hulls in Gardening
Incorporating rice husks in gardens is quite easy. You can follow these steps to for using –
- Spread hulls maintaining about 2-inches layer across the soil surface during the spring.
- You can also mix them into the top 6-inches layer of the soil. It will improve soil properties in the root zone. Also, mixing them with the surface increases aeration.
- If you plan to use hulls for potted plants, you should use 10-50% husks in the mix.
- You can also use hulls as mulching materials like straw.
- Since these materials are extremely lightweight, wind can blow them away.
A gardener can also use this as a mulch. Mulching materials can retain moisture for a longer duration and eliminate weeds.
Rice hulls are considered an effective method to control weeds in the garden. You should use this material as a mulch and cover the soil surface.
Unlike perlite, vermiculite, perlite, and other minerals, rice hulls break down easily in one season. Thus, it is great for adding organic matter to the soil.
Comparison of Rice Hull with Other Soil Amendments
Rice hulls are almost similar to most sustainable soil amendments like coco coir, sphagnum peat moss, and sawdust.
But unlike them, husks are more sustainable and takes time to decompose, though less effective in holding water for a longer period.
But the gardeners get a plethora of benefits from the silica content in the husks.
Here, we will briefly discuss the comparison of rice hulls with the two most sustainable soil amendments – moss and coco coir.
Peat Moss vs. Rice hulls
- Peat is mainly found in boggy areas. It takes thousands of years to form these mosses.
It is not good to harvest these mosses as it is a limited resource in our environment.
On the other hand, rice husks are easy to find. In fact, they are available to every rice mill.
- Both moss and husks are sustainable soil amendments as they can improve soil health.
Peat has a better capacity to absorb water, while hulls can make the soil airy and somewhat less capacity to retain moisture than peat.
- They can improve the overall air and water holding capacity. As a result, root respiration is not hindered.
You can use them in the garden or potting soil.
- Peat can affect the pH of the potting mixes as this material is acidic. In contrast, husks do not affect pH fluctuation.
You can add rice hulls to the peat mix to maintain the balance.
Coco Coir vs. Rice Hulls
- Like rice husks, coco coir (or coco peat) is also considered a waste product of the coconut and is a renewable resource.
Coco coir has a better water retention capacity than the hulls. And husks have a better air retention capacity than coco coir.
- Both coco coir and the husks can be a great addition to the plants. And compared to the coco coir, the rice hull is cheaper.
- Coconut coir is an inert substance that resists decomposition. Also, it does not supply any nutrients to the plants.
At the same time, hulls contain silica that can strengthen the plants’ stems.
- Coco coir can be added to both sandy and clayey soil. But it is better to avoid applying hulls in sandy soil.
- Both of these substances have neutral pH
How to Use Rice Hulls in Gardening?
Rice hulls should be mixed with the soil properly to improve the soil’s physical condition.
Mix them with the top 6-12 inches layer. You may also spread them on the surface.
Do these husks absorb water?
Yes, these materials absorb water and retain it for a longer duration.
What are rice hulls?
Rice hulls or husks are mainly the seed coat that covers the grain.
Are rice hulls good for gardening?
Yes, these hulls are good for gardening, and they are sustainable too.
What is the purpose of mixing the hull with garden soil?
The main purpose of mixing hulls is to increase water holding capacity, cation exchange capacity, and improve other soil properties.
Can I use hulls with peat mix?
Yes, you can. It is a good idea to mix rice hulls to maintain a balanced pH.
You can mix hulls, perlite, vermiculite, and other rock products to improve aeration in your potting soil to increase efficacy.
If you are thinking about hydroponic agriculture, you may also use the mixture of perlite and husks to improve the drainage condition of the medium.
A gardener can obtain the best result if he mixes hulls with other organic matter.
- Demir, Z. and Gulser, C. 2020. Effects of Rice Husk Compost on Some Soil Properties, Water Use Efficiency, and Tomato (Solanum Lycopersicum L.) Yield under Greenhouse and Field Conditions. Communications in Soil Science and Plant Analysis, 52(9): 1051-1068.
- Souza et al., 2002. Silica Derived from Rice Burned Rice Hulls. Materials Research, 5(4).
- Purdue University. 2010. Rice hulls a sustainable drainage option for greenhouse growers. ScienceDaily.
Lindsey Hyland grew up in Arizona where she studied at the University of Arizona’s Controlled Environment Agriculture Center. She continued her gardening education by working on organic farms in both rural and urban settings. She started UrbanOrganicYield.com to share gardening tips and tactics. She’s happy to talk about succulents and houseplants or vegetables and herbs – or just about anything in a backyard garden or hydroponics garden.