Mother Earth Coarse Grade Perlite - 4cu ft

Fine-Granule Sterile Perlite for Blending into Starting Mixes, Grade Coarse

Seed-starting and propagation mixes need a lightweight amendment that opens up pore space without overwhelming a fine-textured blend with oversized chunks. Mother Earth Coarse Grade Perlite is kilned from naturally occurring siliceous rock in a process similar to popping popcorn, which sterilizes the rock and expands it up to 20 times its original volume into granules measuring 1/8 to 1/4in.

At 4cu ft per bag, this granule size is proportioned for blending evenly into soil and soilless starting mixes or for use as a hydroponic rooting and germination medium, where a finer perlite grade distributes more consistently than a coarser one.

Key Features & Benefits

• Expands Up to 20x When Kilned — produces a lightweight, sterile growing media from raw rock
• Neutral pH of 7.0 — will not shift the pH of the growing mix it is blended into
• 1/8 to 1/4in Granules — sized for even distribution when blended into fine-textured starting mixes
• Hydroponics Compatible — works as a rooting and germination medium

Who Should Use Mother Earth Coarse Grade Perlite

Growers blending a fine-textured seed-starting or propagation mix, or who need a sterile rooting and germination medium for hydroponics, will find this grade's smaller granule size distributes most evenly through the blend.

About Mother Earth

Mother Earth's growing-media lineup spans potting soils, coco coir, and perlite, distributed through Hawthorne Gardening Company's branded product pages. Coarse grade sits at the fine end of its kilned perlite lineup, which runs from this seed-starting size up through the heavier-drainage #3 and #4 grades.

Frequently Asked Questions

What does the kilning process do to raw perlite rock?

Kilning heats the raw siliceous rock in a process similar to popping popcorn, which sterilizes it and causes it to expand up to 20 times its original volume. The result is a lightweight, sterile growing media rather than a dense, unprocessed mineral.

Why choose the Coarse grade instead of the #3 or #4 grade?

Coarse grade runs the smallest granule size of Mother Earth's perlite line, at 1/8 to 1/4in, which blends more evenly into fine-textured seed-starting or propagation mixes than a larger granule would. Growers needing heavier drainage in a container mix typically reach for the larger #3 or #4 grade instead.

Will this perlite change the pH of my growing mix?

No, it carries a neutral pH of 7.0, so blending it in should not shift the pH of the surrounding soil or soilless mix. Any pH adjustment still needs to come from your water or nutrient program.

Can this perlite be used in hydroponic systems?

Yes, it works as a rooting and germination medium in hydroponic setups, since the kilning process leaves it sterile and free of contaminants. It is commonly used for starting cuttings or seeds before transplanting into a larger system.

How much Coarse Grade Perlite should I blend into a starting mix?

A common starting ratio runs around 20-30% perlite by volume blended into the rest of the mix, though exact proportions depend on the base media and the crop being started. Adjust the ratio over successive batches based on how quickly the finished mix drains.