• A bag of the product to show the scale of what you will receive, a plastic zip-loc larger that the hand holding it, approximately four by six inches in size.
  • 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.
  • A huernia procumbens succulent in a small black two and a half inch pot with black lava top-dressing.
  • Side-view of the plastic bag full of lava rock, showing it is packed full.
1 5

Black lava sand, coarse-grain horticultural grit

Black lava sand, coarse-grain horticultural grit

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

 

Each bag contains 3/4 LB of black lava sand, coarse. Grain size 1/4 inch down to fines (silt). The sand has been washed and sorted to remove foreign materials and any obvious light-colored chunks. 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!

Black lava sand is finely crumbled volcanic rock. It is a favorite in ornamental gardening, used with succulents, cacti, and even bonsai. It makes a decorative lightweight top-dressing that helps hold moisture in the 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 as an inorganic soil, including stapeliads! The fine gravel can also be used in terrariums and fairy gardens.

The porosity of volcanic rock keeps it lightweight, so roots stay airy and dry. At the same time the porosity retains moisture well. When used as a soil it drains immediately but light moisture remains available to the plant, so it is much more difficult to lose a plant to soggy conditions that cause root rot.

How much do I need? If you aim to use this as a potting medium, a 2.5" square pot holds about 4.75oz (about two and a half uses per bag), and a 4" round pot takes about 15 oz (you'll need 1.25 bags).

ONE BAG - 3/4lb - best for one or two plants, fairy gardens, testing out the substrate.
TWO BAGS - 1.5lb - best for small plant collections, mixing with other substrates, terrariums.
BULK - 5lb - best for more advanced gardeners and larger projects. **Ships for the same price as smaller sizes!

View full details