Perlite is a common name while Pumice may be less common. But upon doing a bit of research on Pumice you will notice it is very similar to Perlite. So, you will wonder which is better Perlite or Pumice?
The main difference between Perlite and Pumice are cost, weight, toxicity, availability, and processing.
People who are more into container gardening, that is flower pots and terrariums may be confused as to using perlite or pumice in the potting mixture. Today we shall have a look at both mediums, and dispel any myths surrounding the two items.
Main Differences Between Perlite And Pumice
Although they both serve the same purpose, there are a few differences. The easy-to-identify difference is that pumice is white in color, more expensive but more porous. Perlite is slightly grayish, easily available, and affordable but needs more processing.
| Characteristic | Perlite | Pumice |
| Color | Multicolored / White / Gray | White / Gray |
| Cost | Less Costly | More Costly |
| Porosity | Lower Porosity | Higher Porosity |
| Weight | Low Weight | High Weight |
| Longevity | Not as long-lasting | Long Lasting |
| Processing | More processing | Less processing necessary |
| Availability | Easy to find | Not as available as Perlite |
| Toxicity | Non-toxic | Its dust can be toxic |
Let us move on now and discuss what Perlite and Pumice actually are, their features use, and their pros and cons.
Related read: Best Potting Soil For Plumeria | How you should choose?
What is Perlite?
Looking at perlite, the small white fragments may look like polystyrene! However, this material we use is created with the addition of water to obsidian, a volcanic glass. Perlite is able to expand upon heating with the appropriate temperature.
Check out 15 substitutes for perlite – Read here
Best Features And Uses Of Perlite
Before processing, perlite can come in colors like red, gray, brown, green, or blue. After the process, they are mainly light gray and white.
Perlite is lightweight and has uses other than the horticultural sector. In other areas, perlite finds use for ceiling tiles, roof insulation, and plaster as it enhances insulation.
1. Improving Water Drainage
Horticulturists and gardeners all over the world use perlite to improve soil drainage. As perlite was originally a rock, it does not blend with the soil. Therefore when dry, the soil does not consolidate into a rock, when using perlite.
This leads to better permeability in the soil. Water is then able to flow out of the pot through the bottom holes since the soil has enough space and water in it.
2. Increasing Soil Aeration
Plant roots need oxygen too. Although you might see plants in places around the home with good air circulation. It can be an entirely different scenario in the pot.
Some people use soil that has more clay or mucky dirt. This will not do as it retains too much water. Roots need air to survive and keep the plant above and below the ground healthy.
Perlite helps this process by providing aeration to the roots. It prevents water accumulation and creates air spaces in the soil.
3. Cost Effective
Perlite is inexpensive. It is one of the main advantages that perlite has over pumice. Unlike other types of soil improvements such as vermiculite, perlite manufacturing is a lot cheaper. Not only that, it is readily available as well.
4. Different Size Options
Fortunately for gardeners, perlite does not come with a “one size fits all” option. There is an international organization that determines the size of perlite. All perlite manufactured must fall between three size categories.
These are:
a. Fine Grade Perlite
This grade of perlite can be blown away by the wind, this goes to show you exactly how fine it is. Fine grade perlite is useful for planting stem and root cuttings.
The largest users of this grade of perlite will probably be nurseries and organizations that are commonly responsible for growing plants from the smallest cuttings.
b. Medium Grade Perlite
This is medium-sized perlite between the coarse and fine perlite. It is applicable in the growth of seeds and seedlings. It provides good drainage and aeration for the seedlings. Mix it at a rate of 50:50 with a good growth medium when planting your seedlings.
This is usually the most commonly used perlite size if you only wish to use it in the garden to grow basic plants.
c. Coarse Grade Perlite
This is the largest size of perlite available. Due to this, it is very porous and has the best draining capacity.
As the particle size is large, it is best in the soil media of succulents, cacti, and orchids. All of the plants mentioned do not do well in soils that retain water. These plants need well-draining and aerated soils.
Orchids and epiphytic plants do not grow in soil as such. They require a chunky medium that is exclusively made up of bark pieces and perlite.
5. Availability
Another reason perlite is so popular around the world is that it is readily available. This is as opposed to coir, pumice, or other soil additives. Hence, you will find that it is an even more popular soil inclusion than pumice.
You can find it at plant nurseries while buying plants or even your local department store will stock this material.
6. Stability
Perlite being an inorganic rock does not disintegrate over time, nor does it release toxins or impurities into the air or soil. It has a safe pH level that does not harm plants. This makes it a safe nutrient-rich and drainage improvement option to use for your plants.
What Is Pumice?
Like perlite, pumice is another rock originating from volcanoes. Its creation occurs when volcanoes eject lava that is extremely hot. The simultaneous cooling and depressurization lead to the rock’s porous air bubble appearance.
Europe produces the largest amount of pumice, due to the large number of volcanoes found there.
Best Features And Uses Of Pumice
Like perlite, pumice helps aerate the soil and is a very good conditioner for soil. It keeps the soil loose and even suppresses weed growth.
1. Facilitates Water Drainage
Pumice assists with good drainage. It prevents the soil from holding onto excessive amounts of moisture. This helps in discouraging fungal and bacterial growth in the soil. Good drainage also helps to flush out any build-up of toxins and minerals from the soil.
Harmful substances are inevitably produced and stay in the soil due to regular fertilizing. By having a well-draining medium, these toxins will be flushed out regularly.
2. Retains Moisture
Although pumice looks like a dry rock, its surface can absorb water. However, it can only retain that extra moisture for 48 hours. It can then release this moisture slowly into the soil.
This is an advantage for succulent and cacti plants which don’t like too much moisture all at once. It can also stop water greedy plants from dehydrating in hot weather.
3. Provides Trace Elements
As pumice is a volcanic rock, it is the source of several types of trace elements. This varies from region to region according to where the pumice was mined. But, overall there could be up to 70 different categories of trace minerals that could be present in the pumice.
This makes it an excellent addition to any potting mix. Providing trace elements at regular intervals can also benefit your soil by keeping it fertile for future use.
4. Loosens Soil
A plant’s underground parts also need air to breathe, carry out reactions, and function. This is when aery soil is mandatory for optimal plant growth. But what can you do if you don’t have great soil? Pumice can help to create these air spaces in your soil.
Roots are especially in need of air, having the pumice present in the lower half of the pot is highly beneficial.
5. Long Lasting
The outstanding advantage of pumice is that it will not break or disintegrate in the soil. No matter how old it may be, this breaking down and disappearing will not be a problem you have to face. Having to replace it time after time would also be very expensive.
Although the pumice might be a bit more pricey, it is a one-time investment. Considering its long life, you shouldn’t have to think twice before buying it if it fulfills all your needs!
6. Excellent Top Dressing
Have you ever watered your flower beds or container and just hated it when the soil splashes onto your dress or shoes? If so, this is another reason why you need to get your hands on pumice, fast!
By using pumice as a top dressing, you will eliminate the problem of losing soil while watering. It can even save dry pot soil from being blown away by a fan if it is indoors. Not to mention that it looks neat and attractive as well.
7. Higher Weight
Pumice is not as light as perlite, a feature you will find quite important. Adding it to your garden pots will increase their weight. Thus you don’t have to worry about your pots being blown over in strong winds or rain.
Plus this can help you to anchor your plants into the soil if they are very heavy! You won’t have to worry about the plant falling out at any time!
8. Large Size Variety
Pumice is usually packaged in transparent packets from which you can see the size of the fragments. You can expect a wide range of sizes, with Pumice measuring one-third to one-eighth of an inch among many others.
You can easily go to a department store or gardening store and fine pumice. Go ahead and pick out the pumice fragment size you feel will be best for your plants. You can ask the store attendant to help you out if you are unsure.
Can I Replace Pumice With Perlite?
Pumice does have a few better properties over perlite, but their main functions are identical. If you want a material that won’t be lost to wind and rain, pumice is better because of its heavier weight.
Also, pumice does not decompose like perlite. Hence, you won’t have to replace it again. These two properties mean you cannot really replace pumice with perlite if weight is an important factor. Also, pumice works out to be more cost-efficient.
Otherwise from the viewpoint of water draining improvement, loosening the soil, and retaining moisture they are equal! Availability near you and cost can also influence your decision. Pumice can replace perlite in general.
Can You Use Perlite And Pumice Together?
You can use perlite and pumice together if you are growing plants that will benefit from their combination. However, first, check if just one of them will suffice in being the sole component necessary.
Conclusion
Perlite and Pumice both originate from volcanic matter. Their use in the gardening world is popular and rightfully so.
- Both materials are useful in soil drainage, moisture retention, and aeration of the soil.
- The main differences include cost, weight, toxicity, availability, and processing.
- Being cheaper or having better availability and no toxicity, Perlite is the better option.
But either is fine if you don’t have any specific requirements besides helping water drain out and have air stay present in the soil.
FAQs
Can I add perlite to cactus soil?
Yes, you can add perlite to cactus soil as they prefer well-drained soil that does not retain too much water for long periods of time. In fact, you will even find that your cacti will thrive in a medium that has high perlite quantity. Perlite is best also to avoid the cactus roots becoming overly wet.
Where else is Pumice used apart from gardening?
Pumice also finds great use in the construction and abrasives industry. This is because of its qualities as being less weighty than concrete, yet more insulating. As for abrasives, you can find pumice useful in industrial cleaning items as well as personal care products such as soap. This is all in addition to its use in horticulture.
