No one is questioning the effectiveness of perlite.
Most experienced gardeners and most beginner gardeners continue to pick perlite when they decide on a soil amendment, but did you know there are alternatives?
A more sustainable one in particular; rice hulls. Which is better, rice hulls or perlite?
When you look at rice hulls and perlite from an economic, environmental, and usability standpoint, rice hulls are better.
Yes, rice hulls and perlite have their drawbacks, but by the end of this article, you will understand why rice hulls have minor advantages that shouldn’t deter you.
Why Rice Hulls are good for plants
Rice hulls are the thin shells on each grain of rice, similar to the husks on corn.
Following harvesting of the grains, the hulls are peeled off and generally burned to discard the byproduct waste from the farm.
That is until someone had the great idea to repurpose the byproduct into something useful.
Now after being peeled away, see the hulls are sterilized by being parboiled, so that it can kill any diseases.
There’s tons of good reasons to choose rice hulls from now on.
Environmental Impact of using rice hull in your garden
We’ll talk about this soon, but perlite is a non-renewable resource that is mined and dug out of the earth with big machinery.
Using a resource that can’t be renewed using machinery that is expelling carbon monoxide and nitrogen oxides to the atmosphere is the direct opposite of rice hulls.
Rice hulls are totally renewable. As long as rice is being harvested, there will be rice hull byproducts.
Good to Know: They don’t need to be mined and the harvesting the hulls doesn’t have the negative effects on ecosystems that peat does.
What Rice Hulls Do For Your Plants
Rice hulls help your plants and gardens in so many ways.
They improve soil texture, they contribute to better drainage, they provide silica, and they can be used as mulch to fight weeds!
When adding rice hulls to your gardens you’ll want to spread a 2-inch layer over your soil, then mix the rice hulls into the top 6-12 inches.
Rice Hulls for plants
Horticulture Grade Rice Hulls, 3lb – 3 Gallon Bag – Listed for organic use, made for greenhouses, vegetable gardens, raised bed gardens, potted plants, house plants, transplanting, soil mixing, crop aeration, and general aggregate substitute.
Cheaper than perlite and vermiculite with additional advantages making this a great “GREEN” substitute.
Pros
- Lower cost
- Naturally breaks up hard soils
- Natural appearance
- Organic Product
- Increases water retention
Cons
- Can blow away in windy areas of the garden
- Needs replacing every few months
Hey there! If you’re considering incorporating rice hulls in your potted plants, you can max it out at a 50 percent ratio of hulls to soil.
When rice hulls are worked in, it will loosen the soil, which helps with stronger root growth, improves drainage in the soil, and provides tons of space for oxygen.
All of these are crucially important for plant growth.
Rice hulls also helps add silica to the soil.
As you may be aware, silica is the key for making the cell walls stronger in plant tissue, and will give the plant more immunity to disease, drought, and heat.
Key Takeaway: Usually, silica has been costly and time-consuming to spray any way before, adding rice hulls in is cheap and fast.
Disadvantages of using Rice Hulls for plants
There’s two drawbacks to using rice hulls:
The first drawback is they start to decompose after a couple years, and as they decompose, the soil will compact once more.
You can remedy this by plopping more rice hulls into the soil. Adding rice hulls once a year can help to keep your soil from compacting.
The second drawback to using rice hulls is they can lead to a nitrogen deficiency.
The bacteria and microorganisms in your soil will use nitrogen to break down any additive that has high carbon content (like rice hulls) and leave very little nitrogen for the plants.
Have you noticed: If you’ve been watching your plants and you see the leaves are turning a pale yellow color, and have slowed down their growth, you may need to add a nitrogen-rich fertilizer.
How much do Rice hulls cost and are they easy to obtain?
Rice hulls are a little tougher to find than perlite, but they are available at specialty shops, some garden centers, and online.
Average cost per lbs: $1/lbs.
Rice hulls are sold in bulk or 50 lbs bags for around $40 to $60.
How much does Perlite cost and is it easy to obtain?
Describing perlite as volcanic glass popcorn isn’t too far-fetched.
This all starts with the process of volcanic eruptions. When lava comes in contact with water, it cools down fast and traps water vapor inside the glass.
This raw glass is mined from a volcanic site and subjected to a temperature of 1,600 degrees F.
Once heated to this temperature, the trapped water vapor is vaporized and expands, causing the volcanic glass to “pop” like popcorn.
When the glass pops, it expands in volume to over 10 times its original size.
After the volcanic glass pops, you are left with a very light weight material with microscopic air comartments.
What Perlite Do For Your Plants?
Perlite helps soils to loosen, prevents soils from compacting, and also helps with both water retention and water drainage.
Whoa, that sounds counter-intuitive; it helps retain water and helps drain water? It isn’t, and here is why.
The perlite is going to give your soil bulk to prevent compacting. The holes being left by the perlite will let the water drain out of the soil.
Promotes Healthy Roots and is great for facilitating Soil. Harris Horticultural Grade Perlite is ORGANIC and helps soil to retain moisture and keeps nutrients available while preventing soil compaction allowing your plants to grow better than ever.
Pros
- Aerates Soil
- Improves Drainage
- Prevents Compaction
- Promotes Moisture Retention
- Promotes Root Growth
Cons
- Looks visually untidy
- Impact on the environment
- An 8-quart bag does not go far
- Costly
If the soil has become compacted, that water has nowhere to drain. It cannot leave the dirt until it evaporates, or somehow makes it way through the pot, which results in root rot.
And those small air pockets?
They are trapping water molecules as the water is moving through soil. The pockets are too small to hold much water, just a little.
Then as the soil dries out, it pulls moisture from the perlite, where your plants can access it.
If you don’t want to buy premade soil mixes, you can make your own. The best ratio when making your own mix for pots is one part loam, one part peat, and part perlite. This mixture provides the best amount of structure, drainage, water retention, and helps the soil from compacting.
Perlite is great for propagation too!
Get a Ziploc bag, and fill it with moist perlite. When you have a cutting that you want to root, place the bottom into the perlite up to a node.
Fill the bag up with air, and seal shut. Keep out of direct sunlight, and check back once three weeks has passed.
Your cutting should have rooted, and you should be able to plant this cutting.
What are the disadvantages of using Perlite for plants?
Perlite has a few downsides:
The first downside is its light weight. Sure it helps with soil, but it can be blown away with wind, or washed away with rain. It is so light, it actually floats in water.
Perlite can also cause lung and eye problems if not handled properly. If you’re working with perlite, you should always put on a pair of goggles, and a mask or you can easily irritate your eyes or lungs with the dust.
The biggest downside to using perlite is the impact on the environment. Perlite is a non-renewable resource. We can’t make any more, we can only mine whatever is there.
Looks bad, it’s like styrofoam balls.
Expensive, an 8-quart bag does not go a long way.
The mining and processing of perlite are also terrible for the environment.
The machines required to mine and process perlite contribute CO2 emissions and the energy needed to heat the perlite to a whopping 1600 degrees F is not good either.
Cost and Availability of Perlite for gardeners
Average cost per lbs: $5/lbs.
You can find perlite at your local garden store or on Amazon. It comes in much smaller bags; for about $10, you can get 2 lbs.
However, you’ll be surprised to find you need more than you think. I bought an 8-quart perlite bag when I first started gardening and didn’t know better and it didn’t last very long at all.
Quick fire FAQ’s about Rice Hulls vs Perlite
Can rice hulls and perlite be used together in soil mixes?
For sure, you can totally use rice hulls and perlite together in soil mixes. They have complementary properties that can enhance soil structure, drainage, aeration, and nutrient availability. Rice hulls can also improve soil structure, and provide nutrients to plants while perlite improves drainage and aeration.
How do rice hulls and perlite affect soil pH?
Rice hulls are slightly acidic, so they can affect soil mixes to reduce the acidity of the soil. Perlite is not acidic and pH neutral and does not affect soil pH.
Can rice hulls be used for succulents?
For sure, rice hulls can be on succulents. Rice hulls can hold water pretty well and contribute to soil structure, both of which will be beneficial for growing succulents. As rice hulls break down over time, they can also provide nutrition in the soil.
Can rice hulls or Perlite be used around Children and Pets.
Both have risks, rice hulls are natural but they could cause choking if consumed. It is better to handle perlite with gloves and a mask so you don’t irritate your skin or lungs while handling it. Perlite dust can irritate your eyes and your lungs so it is best not to inhale it.
Is perlite unsustainable?
Perlite is considered a sustainable resource. Perlite is naturally sustainable volcanic glass formed from different deposits created from cooling lava around the Earth. It was created when lava cooled rapidly and trapped water.
This means Perlite is not a non-renewable resource such as oil, coal, or gas; it is a naturally occurring mineral, and it was found in significant deposits all around the world.
Why I use Rice Hulls over Perlite ?
They both work great for gardens so trying to decide which one was was much harder than I thought it would be.
It really came down to cost, how easy it was to use, and their eco friendliness.
Rice hulls come at a fraction of the cost of perlite, don’t require protective gear to handle, and a renewable product that was once considered a waste.
This is what made the rice hulls better than perlite. Plus, it makes me feel good that I am using natural products on my plants.