Grain Spawn Jars

Sterilized Grain Spawn Jars

Below you can find our full selection of sterilized grain spawn jars for mushroom cultivation. We offer rye berry, popcorn, red milo, white milo, white millet, BRF with vermiculite, and blended grain mixes, available in pint and quart sizes.

All grain spawn jars from Out-Grow arrive fully sterilized and ready for inoculation. Most jars include a self-healing injection port and a 5-micron filter patch.

Rye Berry Grain Spawn Jars

Rye berry is one of the most widely used grains for mushroom spawn production. It provides high surface area for mycelium colonization and works well across a broad range of species. Available in pint and quart sizes.

Popcorn Grain Spawn Jars

Popcorn is a popular alternative grain known for fast colonization and good water retention, and is well suited for a wide variety of gourmet and medicinal species.

Red Milo and White Milo Grain Spawn Jars

Milo grain provides a small kernel size with high surface area, supporting fast and even colonization. Available in both red and white varieties in quart size.

White Millet Grain Spawn Jars

White millet is a small grain that colonizes quickly and is well suited for species that benefit from a higher number of inoculation points.

BRF & Vermiculite Grain Spawn Jars

Brown rice flour and vermiculite jars are the foundation of PF Tek, one of the most widely used beginner cultivation methods. Available in half pint size.

Blended Grain Spawn Jars

Our Mega Mix grain spawn jars combine rye berry, red milo, and popcorn in a single jar, providing varied texture and multiple inoculation point sizes in one product.

Browse the full grain spawn jar collection below, organized by grain type and size.