How To Grow Mushrooms On Logs Or Stumps Using Mushroom Plug Spawn

Welcome to the official Liquid Fungi guide to using Mushroom Plug Spawn! 

Mushroom plug spawn is used to inoculate freshly cut solid hardwood logs or stumps with mushroom mycelium, in order to grow mushrooms directly from the log or stump. While plug spawn is active fungi culture and can be transferred to any medium, it is typically used exclusively for this purpose. This methodology has the best long term return on investment, producing mushrooms for 5+ years. However, you will have to wait around a year to see your first mushrooms, because it takes time for that mycelium to work itself through the dense wood initially.

The Pros

  • Best return for time invested.
  • Does not require a flow hood or sterile equipment.
  • Can be done with basic drill and hammer.
  • Low tech outdoor growing.
  • Produces mushrooms for many seasons.
  • Easy to maintain after setup.
  • One of the oldest known cultivation methods.

The Cons

  • More up-front work preparing logs.
  • You must have freshly cut hardwood available.
  • Inoculation and harvesting must be timed with the seasons. 
  • You must wait about year before getting your first mushrooms.

Selecting Your Mushroom Species

This methodology can only be used for hardwood loving mushroom species like Oyster Mushrooms or Lion's Mane. These species require a hardwood substrate to grow. This methodology will not work for compost/bovine loving mushroom species such as Portobello. 

Selecting Your Wood

You will specifically need hardwood such as Alder, Ash, Birch, Bitternut, Cherry, Chestnut, Hophornbeam, Ironwood, Maple, Oak, Pecan, Sweet gum, Sycamore, Tulip poplar, Walnut, Willow. They do not grow on pine/conifers. The hardwood logs need to be freshly cut, within the past 20 days. Logs should be 4-10 inches in diameter, and cut to consistent length so they can be organized in stacks. We suggest cutting them 2-4 feet long. If you intend to inoculate a stump, it must be fresh cut as well. This is a good way to naturally break down stumps over a few years and turn them into something useful.

Inoculating and Cultivating the Fungi

Logs are typically inoculated after the last frost in early spring, and harvested the following spring. Simply drill 5/16" holes 1" deep to hammer the plug spawn into. The holes should be drilled right before plugging them, and spaced about 4" apart. After inoculation, Place the logs in a shaded area or incubation container. The logs should not be placed in direct sun or they will dry out quickly. Many people stack the logs into piles or towers under tree cover. This allows them to be protected from the sun, but still receive natural rain. Preventing the logs from drying out is important, and the more moisture they retain, the better they will incubate and fruit. If it does not rain for a couple weeks, it is a good idea to water the logs yourself. 

Mushroom Fruiting & Harvesting

After incubating for a year, the logs will begin to produce mushroom fruiting bodies. They will produce consistently throughout the season as long as they have ample moisture available. It is a good idea to drown soak or water your logs between fruiting flushes. Adding moisture back into the wood will increase mushroom production and yield.