The key to a thriving garden is healthy soil, and that’s true no matter what you’re growing. To get the best soil possible, you sometimes need to add certain materials or adjust its makeup, and lava rocks are one of the most popular ways to do it.
What are lava rocks? Lava rock used in gardening is often applied to soil as an aggregate that improves drainage and the capabilities of the roots.
The small rocks can be mixed through the soil or sat on top of the garden bed or pot with porous characteristics that make it ideal for all types of plants.
If you’re ready to see what this natural substance can do but are wondering where to buy lava rocks and which ones are worthy of your garden, we can help with all of that.
We’ve rounded up a handful of the best black lava rocks made for the garden, so your plants can start reaping the benefits right away.
Our “Best Lava Rocks” review includes:
- Bonsai Supply Soil Aggregate
- Toypopor Lava Rock
- Hoffman Volcanic Lava Rock
- Carurbody Red Lava Rocks
- Oupeng Lava Rock Pebbles
Best Lava Rocks For Your Garden — the Review
The simple act of adding lava rocks to plants and their soil comes with major benefits, as long as you choose the right ones. To ensure you’re using only the best lava rocks for your garden, check out our hand-picked favorites to see what we recommend.
Bonsai Supply Soil Aggregate — Best Overall
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The Bonsai Supply Soil Aggregate contains a mixture of ¼ inch red lava rock pieces and is designed for use with plants like orchids, cactus, and other container varieties.
Coming in a large two-quart bag measuring 2.76lbs in total and featuring a sealable zip-top, you’ll have more than enough to cover your whole plant collection.
Bonsai Supply Soil Aggregate is a must for surrounding any plant that needs better drainage and aeration, and it’s easily our favorite find.
The ¼ inch red lava rocks can be added to the soil mixture and will help the roots split into smaller feeder roots as well as make it easy for the soil to retain moisture without becoming waterlogged.
Unlike lava rocks for landscaping, the smaller size of these makes them more practical in the garden. Customers loved how easy they were to sprinkle on top of potted plants or mix through the soil of those that needed help with drainage.
You only need a small amount to get results for your garden as well, so there’s not much effort required for major benefits.
Cost-wise, the Bonsai Supply Soil Aggregate is one of the best, and when you purchase in this larger bag, you’re able to save even more. Although the size is bigger than most, they’ve thought of the gardener when packaging it, because it comes with a resealable top that you can open and close as needed, ensuring the product stays fresh.
Better still, the materials used to make the bag are 100% recycled, and the rock is sourced from Utah, so it’s another tick for the company.
On the downside, some people found the size of the lava rock itself to be on the small side. According to Bonsai Supply, the rocks measure a ¼ inch but there were some smaller ones that ended up at the bottom of the bag.
Another potential downside that might affect some customers is that these lava rocks are red and not black. Although the color doesn’t impact its ability to drain, it can stand out amongst the soil in your potted plant, so consider whether this works for the gardening layout you’re going for.
Bonsai Supply has created a budget-friendly and effective way to improve the drainage and health of your soil, no matter the type of plants you’re growing.
The large two-quart bag has enough lava rock to cover a range of container plants and to scatter on top of your garden beds, so check out our favorite choice to see what the fuss is about.
Specs
- Volume: 2.76lbs
- Rock Size:0.25 inches
- Color: Red
Pros
- For how much lava rock you get, this is easily one of the better-priced quality raw materials for the garden.
- Having a resealable bag means everything stays fresh until it’s ready to be opened again.
- You’re buying from a brand that’s built in the US and sources its materials there, which is a win-win.
- You only have to sprinkle a small amount of rock into the soil for it to deliver benefits to your plants.
Cons
- Not every gardener will like the red color of these lava rocks, so if you’re hoping for a more discreet black rock, this isn’t it.
- The smaller-sized individual rocks might not be effective for drainage, and we’d like to see fewer of them in each bag.
Toypopor Lava Rock — Runner Up
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Toypopor’s Lava Rock comes in a 2.2lbs bag featuring black rocks that measure between 0.3 inches and 0.4 inches in size.
As a multi-use volcanic rock, you can mix it through the soil for correction, add it to planters for drainage, or just use it as a decorative dressing.
It has high-temperature tolerance and excellent porosity, so it can be used for all aspects of gardening.
If you want a larger lava rock that’s more versatile than the competition, look no further than Toypopor. Their 2.2lbs bag of black lava rock can be used for top dressing, drainage, soil correction, water features, and even in fire pits, making it a truly multipurpose option.
The best thing about these rocks was their size, with each one measuring between 0.3 inches and 0.4 inches.
They’re the perfect size to add drainage to the soil but without falling through the holes in your planter like some other lava rocks have been known to do. You can also use it as a soil additive for plants that need it.
Another bonus of shopping with Toypopor is the appearance of their lava rock and its striking black color, which is great for people who take pride in how their plants look. Better still, the rock has a high-temperature tolerance so you can even use it in fire pits or warmer climates without worrying about it degrading.
The negatives of this lava rock are mainly to do with its price, as there are larger backs of this type of rock available for the same price. You’re likely paying for the black coloring of the rocks so if you’re not fussed about what they look like, there are probably cheaper alternatives you can choose from.
Another downside to Toypopor is that there’s minimal information available about the brand and where they sourced this volcanic rock from. If you’re someone who prefers to shop for American sourced materials for the garden, these aren’t ideal.
Toypopor’s Lava Rock might be a little more expensive, but those who have used it can vouch for its greatness. The large 2.2lbs bag can be added to loads of potted plants or applied as decorative dressing, and with its special black coloring, it’ll add a practical and beautiful boost.
Specs
- Volume: 2.2lbs
- Rock Size: 0.4inches
- Color: Black
Pros
- The color of this lava rock makes it easy to mix through soil or sit on top as a dressing, and it blends in beautifully.
- With a high-temperature tolerance, there are more ways to put this rock to work than just the garden.
- Each rock measures around 0.4 inches so they’re large enough to provide good drainage and not fall through the bottom of the planter.
- These rocks have a high porous factor so they can help with plants that need more drainage in the soil.
Cons
- Although not expensive, these rocks are priced slightly higher than others coming in a 2.2lb bag, so keep that in mind.
- There’s little information available about the Toypopor brand if you prefer to buy from a company that sources its materials within the US.
Hoffman Volcanic Lava Rock — Alternative
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Hoffman’s Volcanic Lava Rock is a 3lbs bag of bright red rocks designed for dressing your garden. Each rock measures around 0.7inches but there’s a good mixture of sizes within, and they come in a resealable bag for your convenience.
These larger volcanic rocks are ideal for decorative purposes and can be added to the soil of larger container plants.
Hoffman’s Volcanic Lava Rock is another of our favorite finds for your garden, and they’re the perfect choice for people wanting more of a top dressing material.
The bright red rocks help with drainage and improve the look of your garden and container plants instantly, no matter what you’re growing.
The benefits of Hoffman’s rocks are that they’re affordable and easy to use, as well as feature a resealable bag that lets you keep them for longer. You’ll get a whopping 3lbs of rocks for the same price that other brands charge for just 2lbs, and they’re just as high in quality as well.
Another selling point for Hoffman’s is that their rocks are a beautiful bright red color that stands out in a good way.
The rocks are larger than most, which can be a good and bad thing, but if you’re after a top dressing for the garden or something to go with your bonsais, the larger size makes them perfect.
On the downside, this larger size can also make them cumbersome to work with. People with smaller potted plants or plant varieties might find that the larger dime-sized rocks in this bag are overwhelming, so do some measurements before you commit.
Another potential negative is that they’re not really ideal for soil correction, so if you’re trying to adjust pH levels or anything else, choose another volcanic rock. These are red lava rocks that are better suited to soil drainage or providing a decorative landscape dressing, so don’t confuse the two.
Hoffman is one of the only brands that offer a satisfaction guarantee on their lava rocks which proves how good they are. If you’re looking for drainage and decoration and prefer a brighter red look, you’ll love everything about these.
Specs
- Volume: 3lbs
- Rock Size: 0.7 inches
- Color: Red
Pros
- The vibrant bright red color is hard to come by and it’s great if you’re looking for a standout dressing for your garden.
- The larger size of these makes them a good fit for decorative purposes and placing on top of the soil.
- For this 3lbs size bag, these rocks are one of the cheapest, so they can help you garden on a budget.
- Comes with a quick zip resealable bag so you can keep the excess rocks stored in good condition.
Cons
- These lava rocks are marketed as being a decorative feature rather than one used for soil correction, so keep that in mind.
- As larger rocks, they might not be ideal for smaller pots, with each one measuring around the width of a dime.
Carurbody Red Lava Rocks — Alternative
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This 2.2lbs of red lava rocks from Carurbody is ideal for container plants that require some help with drainage and gardens that prefer a smaller-sized rock.
The rocks are naturally colored with no dyes, sized at around 0.3 inches width each, and come in a handy resealable bag for your convenience.
Carurbody has packed these all-natural Red Lava Rocks for you to use in your garden, and they’re one of the best out there. The 2.8lbs bag of rocks is ideal for any plant that needs help with drainage, and because of their beautiful, natural coloring, they add a great decorative touch as well.
According to customers, the best thing about Carurbody’s rocks is how effective they are with drainage. If you have plants that regularly suffer from root rot then placing a handful of these at the bottom of the container is all you need to do to rectify it.
The smaller size of these rocks means you can cover more ground with them, and most people found that a single bag was enough for up to 12 potted plants. Although the bag weighs less than most at around 2.2lbs, it requires less product to work, so it evens out in the end.
The sealable pouch helps you to store them away so they stay fresh as well, and because they never erode, one bag can last for years.
You’ll be somewhat limited on the types of plant containers you can use these with because of their size, which means anything with drainage holes is off-limits.
The smaller size of the rocks means they’ll fall out with each watering if there are holes to go through, so if you have anything larger than 0.3 inches, they won’t be suitable.
Another downside to these lava rocks is that they come with a lot of dust in the bag, which nobody wants when they’re spending this much money. Customers mentioned having to wash the rocks off before they started using them which is annoying and makes it harder to place them back into the bag for storing if they’re wet.
Carurbody’s Red Lava Rocks are all-natural and highly effective for the garden, as long as you use them right. If you prefer the reddish hue of lava rock and need something that’s adept at drainage, you won’t mind paying a little extra for the benefits they offer.
Specs
- Volume: 2.2lbs
- Rock Size: 0.3 inches
- Color: Red
Pros
- Those wanting smaller rocks for smaller containers will love the size of these.
- The natural red color is achieved without any dyes so you can feel good about putting them in your garden.
- You’ll get a total of 2.2lbs in each bag which is enough to cover up to 12 containers.
- One of the best options for providing drainage at the bottom of plants if you have issues with root rot.
Cons
- These are suited to containers with no drainage holes because otherwise, they can fall out of the bottom.
- Some customers found that the bags had a lot of dust in them which means the rocks had to be washed off first.
Oupeng Lava Rock Pebbles — Alternative
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Oupeng’s Lava Rock Pebbles come in a bulk size of 5.7lbs and feature all colors and shapes of lava rock.
These mixed rocks are ideal for drainage, decorative dressing, and maintaining moisture, no matter what plants or containers they’re added to and they can also be added to fish tanks, fire pits, and more.
If you have a large garden or the need for a lot of lava rocks, look no further than Oupeng. They’ve packaged a massive 5.7lbs of lava rocks into one bag, featuring a unique mixture of red, gray, and black colors as well as all shapes and sizes.
The coolest thing about these rock pebbles is their drainage ability, and if you’re looking to improve the health of your plants’ roots, they’re one of the best. Because they have a mixture of sizes and shapes they’re fast draining and they won’t all out the bottom of the container like others do.
Another bonus of the Oupeng Lava Rock Pebbles is the price, thanks to the bulk size they come in. You can save over around $30 buying in bulk like this, and because they can be easily sealed up and stored away, there’s no need to use them when they arrive.
The negative side of having such a large amount of rocks is that they create a lot of dust during transportation. This means people had to wash their rocks off two or three times before they could add them to the soil.
Another downside of buying cheaper lava rocks is that the quality suffers somewhat, and this is true with the Oupen brand. They do a good job of providing drainage still, but a closer look at them will show they don’t appear to be the same texture as more expensive lava rocks, which could be a negative.
Oupeng’s Lava Rock Pebbles are our favorite pick if you’re after affordable and large quantities of this raw material. Their rocks are naturally colored and you’ll find no fillers or additives in the bag, so if you want an easy way to improve drainage and the health of your plants, Oupen is one of the best.
Specs
- Volume:5.7lbs
- Rock Size: Mixed
- Color: Mixed
Pros
- This bulk packet of lava rock pebbles is the cheapest, so if you need more it’s the best way to buy them.
- A colorful mix of black, grey, and red lava rocks looks amazing in all types of garden settings.
- The rocks are both smaller and larger-sized ones so they’re great for improving drainage.
- You can use these in all sizes of containers and even those with holes, and they won’t fall out.
Cons
- Customers found a lot of powder in each bag of pebbles which had to be washed off at least twice before they could use them.
- The overall quality of these lava rocks is slightly less than more expensive brands, and they’re not as beneficial for soil correction.
Lava Rocks FAQ
There are all kinds of wonderful things you can add to your soil to improve its performance, but lava rocks are known as some of the best.
If you’re still wondering what lava rocks can bring to the table, check out these FAQs that will answer all of your questions about the wondrous natural material.
Is Lava Rock Good For Your Garden?
Lava rock is a natural material sourced from volcanic rock and it offers advantages like improved drainage, retaining moisture, and strengthening roots.
The addition of the rocks to the top of the soil or mixed through it can be hugely beneficial, depending on the type of plant and soil it’s added to.
What Is The Difference Between Red And Black Lava Rock?
The color of lava rock is determined by the cooling process it underwent and the minerals that it contains. When applied in smaller pieces in the garden, black and red lava rocks are much the same, with benefits being improved drainage and moisture retention.
Red lava rocks are used in the garden for decorative purposes and to assist with drainage, mainly as they contain fewer minerals, whereas black lava rocks can improve drainage and allow for better root growth.
Are Lava Rocks Better Than Mulch?
There are certain advantages that lava rock has over mulch in the garden, including the fact that they don’t decompose and they’re heavy enough to stay put where they’re placed.
However, the benefits of organic mulch materials are their ability to feed nutrients to the soil and improve its quality over time.
What Plants Grow In Lava Rock?
The best plant varieties for growing in lava rock include succulents, Tillandsia, and certain grasses.
Placing lava rock in a planter will help with soil drainage and it can be used with all kinds of plants inside and outside of the house, as long as the plants don’t require constant moisture.
The Lava Rocks That Rock
If you want to improve drainage and support root health in your garden, the addition of lava rocks is a powerful way to do it. With our top picks for lava rocks and some insight into what they can do, your plants will be thriving in their new soil home.
