Expanded perlite is offered in two particle sizes: fine (1–3 mm) and medium (3–6 mm), both in 60 L bags. Both share the same origin and general behavior, but the difference in particle size changes their agronomic function: the fine improves aeration without significantly altering the texture of the base substrate; the medium drains more strongly and adds macropores to the root ball. This comparison helps you decide which to combine with your substrate.
🎯 Choose the variant in 10 seconds
- If your case is seedbeds, cuttings, or fine substrate for small pots: go to the fine variant (1–3 mm)
- If your case is deep pots, hydroponics with frequent irrigation, or ornamentals that require drainage: go to the medium variant (3–6 mm)
What to consider before choosing a variant
Both variants share the same mineral origin (perlite expanded by thermal shock), the same chemical inertness properties, and the same 60 L bag presentation. The choice comes down to particle size. These are the key criteria:
- Pot/container size: In germination trays and small pots (≤ 1 L), fine perlite integrates better with the substrate and does not "float" upwards. In deep pots and large containers, the medium perlite drains more and maintains available air in the root zone.
- Base substrate: When mixed with peat or fine coco fiber (Pith), fine perlite retains texture and slightly increases aeration. When mixed with coarse substrate (coco chips, bark), medium perlite acts as a draining supplement without collapsing the mixture.
- Irrigation frequency: The more frequent the irrigation (hydroponics, daily fertigation), the more medium perlite is needed to ensure root oxygenation between waterings. The less frequent the irrigation, the more fine perlite is needed to help retain moisture through capillarity.
- Mixing ratio: As a reference, 20–30% perlite in the base substrate is most common for standard pots; 40–50% for cutting substrates or hydroponic crops. Mixtures with more than 60% are used in specific systems where the inertness of the medium is desired.
- Handling and dust: Being a lightweight porous material, perlite generates dry dust when handled. Lightly moisten the bag before mixing, or work outdoors with a mask. Medium perlite produces less dust than fine perlite.
Fine variant (1–3 mm): the mix for seedbeds and small pots
- Particle size 1–3 mm: homogeneous integration
- Improves aeration without altering the texture of the base substrate
- Suitable for germination trays and cuttings
- High capillarity: helps distribute water
- Generates dust when handled dry
- Less vigorous drainage than medium
- Insufficient for large pots with frequent irrigation
Fine perlite is the standard choice for mixing with peat, Pith coco fiber, or fine commercial substrates. Its small particle size integrates homogeneously without creating layers and improves the aeration of the root ball without turning the substrate into a draining medium. It is the natural option for seedbeds, plug nurseries, and propagation by cuttings, where the medium must remain moist but aerated.
Medium variant (3–6 mm): the drainage for deep pots and hydroponics
- Particle size 3–6 mm: drains strongly
- Creates macropores: oxygenation between waterings
- Suitable for hydroponics and NFT with frequent irrigation
- Less dust than fine perlite when handled
- Lower capillarity: faster drying
- Not recommended for germination trays
- Can separate from fine substrate with intense watering
Medium perlite is the option for large pots, deep containers, and any system with frequent irrigation where the main risk is root asphyxia. In hydroponics with substrate (coco fiber grow bags, NFT system with filling) or in ornamentals that do not tolerate waterlogging, medium perlite ensures that the root zone has oxygen between waterings. It is also used as a drainage layer at the bottom of deep pots before adding the main substrate.
Comparison table of variants
Both variants share all the material properties and differ only in particle size and, consequently, in their effect on the substrate.
| Characteristic | Fine (1–3 mm) | Medium (3–6 mm) |
|---|---|---|
| Ideal use | Seedbeds and cuttings | Deep pots and hydroponics |
| SKU | 642346 | 756799 |
| Particle size | 1–3 mm (0.04–0.12 in) | 3–6 mm (0.12–0.24 in) |
| Capillarity | High | Medium |
| Drainage | Medium | High |
| Root aeration | Good | Very good |
| Dust when handled | More | Less |
| Bag volume | 60 L (15.8 gal) | 60 L (15.8 gal) |
Use case matrix → recommended variant
| If your case is… | Recommended variant |
|---|---|
| Germination tray with fine substrate | → Fine |
| Propagation by cuttings in small pots | → Fine |
| Mixing with peat or Pith coco fiber for standard pots | → Fine |
| Hydroponics with substrate and frequent irrigation | → Medium |
| Deep pot with plant sensitive to waterlogging | → Medium |
| Mixing with coco chips or bark for ornamentals | → Medium |
Perlite is always mixed; it is never used alone in cultivation (except in specific hydroponic systems). As a quick reference: for standard pot substrate, use 20–30% perlite; for cuttings and rooting, 40–50%; in hydroponics with pure perlite, up to 100% in systems with automated irrigation and nutrient supply. If your mixture feels "heavy" after a couple of waterings, it needs more perlite; if it dries too quickly, it has too much and you should reduce it.
Do not handle perlite dry without respiratory protection. The dust is light and remains suspended; although not toxic, it irritates the respiratory tract and eyes. Before mixing, lightly moisten the bag with a sprayer or work outdoors with a mask and goggles. Medium perlite generates significantly less dust than fine perlite, but caution applies to both.
Frequently asked questions
Perlite or vermiculite: which one should I choose?
Perlite drains and aerates, retaining hardly any moisture. Vermiculite retains moisture and provides capillarity, without draining as much. For substrates that tend to compact and need air, use perlite. For substrates that dry out too quickly or for seedbeds with infrequent watering, use vermiculite. Many nurseries mix both (50/50) to obtain a balanced substrate in aeration and retention.
Does perlite provide nutrients?
No. Perlite is chemically inert: it neither provides nor absorbs nutrients. All nutrition must come from the base substrate (peat, coco fiber, compost) or from fertigation in hydroponic systems. Its function is strictly physical: to aerate, drain, and maintain structure.
Can perlite be reused?
Yes. As it is inert, it retains its physical properties after a growing cycle. To reuse, separate the perlite from the substrate (washing with water is usually enough because perlite floats), rinse it, and if you want greater sanitary safety, dehydrate it in the sun for a few days or submerge it in 60 ºC (140 ºF) water for 30 minutes to reduce pathogens. In crops with a high incidence of soil diseases, do not reuse and discard the entire substrate.