• A hand full of black lava gravel, small angular pieces of porous rock. The smallest are the size of sand grains, while the largest are around a centimeter.
  • A birds-eye view of a bowl of multi-colored lithops, with black lava gravel as top dressing. The dark rock makes the plant colors of purple, orange, white, and green pop.
  • Four brown paper bags full of black lava sand arranged on a garden table, demonstrating the different sizes available. There is a large scribble over the image with text reading 'sizes updated! all options slightly bigger then this now'
  • A huernia procumbens succulent in a small black two and a half inch pot with black lava top-dressing.
  • Diagram indicating the lava gravel provides good heat retention over winter, but can lead to plant burns if used in direct summer sun conditions
1 5

Black lava sand, 1/8-minus

Black lava sand, 1/8-minus

$4.00 USD
$4.00 USD
Sale Sold out
Shipping calculated at checkout.
Size

Lava sand, 1/8"-minus containing up to 40% fines (silt)
The material has been screened to remove foreign materials and reduce fines.

Available in sizes: 1/2 qt (1 lb), 1 qt (2 lb), 3 qt (6 lb), 8 qt (16 lb)
HOW MUCH DO I NEED? 1 dry qt is the equivalent of a 32oz deli plastic container (filled), equal to about 2 pounds of lava sand.

Black lava sand is finely crumbled volcanic lava cinders. It is a key component of DIY Pon mixes for succulents, cacti, aroids, hoya, bonsai, and carnivorous plants. The fine gravel can also be used in terrariums and fairy gardens. It is a decorative lightweight top-dressing that helps hold moisture in soil. Alternatively, mix it into the soil like perlite for a lightweight grit.

There are many cacti and succulents that are happy to be planted directly in lava sand or lava rock mixed with other rock types to create an inorganic soil—it more closely mimics low-nutrient natural growing conditions. The porosity of volcanic rock keeps soil lightweight, so roots stay airy and dry. At the same time the porosity retains moisture well similar to LECA, so lava rock soils drain immediately but light moisture remains available to the plant. This makes it much more difficult to lose a plant to the soggy conditions that cause root rot. (And dissuades fungus gnats)

This material is mined in northern Arizona, and characteristic of the region's material I have found some tiny bits of peridotite/olivine mixed in!

View full details