Pozzolan for mulching or drainage in the garden or in your pots

Pozzolan is a natural draining material which is used a lot in the garden but also for plants grown in pots or trays. Let’s see what exactly pozzolan is, what are its main advantages and how to use it.

What is pozzolan?

It’s about a rock from volcanic slag. It is also called the lava rock. It is a material 100 % naturel with an alveolar structure whose density is around 800 to 900 kg/m3.

Pozzolan is used in many fields such as cheese making because it is used for refining, aquariums, construction, sanitation, septic tanks, protection of spreading networks, lagooning, underground backfilling for road construction for example, above-ground agriculture where it enters into the composition of the substrate or even gardening, whether for plants in the ground or in pots.

If pozzolan is also used it is because it is an interesting material at different levels: it is natural, light, porous, crumbly and sandy.

What are the main advantages of pozzolan?

Lava stone is a material that is difficult to do without because of its special characteristics.

  • Durable,
  • Resists all types of weather,
  • Does not break down over time,
  • Does not acidify the soil,
  • Has good water retention capacity,
  • Draining due to its porosity,
  • Easy to carry,
  • Easy to handle…

Pozzolan is widely used in the garden and in pots. It’s a real ally of plant lovers who appreciate the multiple benefits of this amazing rock, namely:

  • Limits the phenomenon of beatthat is to say the compaction of the soil by water which disturbs the penetration of water and air into the earth.
  • Facilitates the work of the soil since it settles less if it is protected by a mulch of pozzolan,
  • Stabilizes the environment of underground fauna which benefits the garden by transforming organic matter into humus,
  • store heat,
  • Limit watering,
  • Reduces the time devoted to weeding since it reduces the growth of weeds,
  • Protects plant roots against frost,
  • Limits the risk of cryptogamic diseases because a pozzolan mulch prevents splashes on the foliage and therefore the dissemination of spores,
  • Keeps slugs and snails away as its edges are sharp.

Pozzolan is also capable of highlight the plants at the foot of which it is used as mulch. Depending on the degree of oxidation, its red, brown or black color seems to change depending on the brightness. In cloudy weather, its shade is dark, and on sunny days it is much more colorful.

What are the main uses of pozzolan?

This light and porous but also decorative material is very versatile since it can be used:

  • As mulch in the vegetable garden, in the orchard, in the pleasure garden, in the pots and planters on the terrace,
  • As draining integrated into the soil for potted and container plants that are grown indoors such as orchids, bonsai, exotic plants, succulents,
  • As a draining layer which covers the fund des cans before placing the compost or to put at the bottom of the planting holes if the garden soil is clayey,
  • As ground cover for an effect that is both protective and decorative, whether in flowerbeds, rockeries, along the path,
  • As protection of fruits and vegetables such as strawberries, tomatoes, squash for example since thanks to a layer of pozzolan spread at the foot of the plants, the good garden products are no longer in direct contact with the ground. They are therefore cleaner and are less exposed to the risk of damage.

We can use it alone or combined with other materials in order to create a beautiful harmony during the development of a landscaped garden for example.

It should however be noted that pozzolan does not add nutrients to the soil. It is a mineral element that is used in addition to an organic mulch. Placed on a compost for example, the lava stone brings an aesthetic touch.

Where to find pozzolana?

Everyone can buy pozzolan in the garden center where it is marketed in bulk or in bags in the mulch section. We find her in blocksit is then rather intended for the creation of rock gardens, finely ground or even in different grain sizes, 7-15mm, 12-20mm and 20-40mm. A small particle size is mainly used to form a substrate, while a large particle size is perfectly suited for mulching.

As an indication, there are approximately 70 to 75 kg pozzolan with a grain size of 6-12 mm per m². We therefore buy it in bulk if we want to cover a large garden area with this volcanic rock. It is necessary to count between €12 and €15 for a 20-litre bag i.e. about 16 kg.

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