Avoiding Mistakes in Mushrooms: A Troubleshooting Guide

Environmental factors, contamination and plain bad luck are among the things that make mushrooms fail. Here are ways to determine the source of the problem.

by Jereme Zimmerman
PHOTO: Jereme Zimmerman

If the appropriate steps are followed, mushroom cultivation can be a fairly simple process and can result in years of successful harvesting. However, fails happen. Whether it’s bad luck, environmental factors or contamination, sometimes you need to take a step back to determine the source of the problem with your mushrooms.

When troubleshooting, first examine your overall technique before attempting to isolate the source of the problem, as improperly executing one part in the process can exacerbate other problems. Of course, eliminating potential problems in the first place is always the best option.

For some problems, once they’re discovered, it might be too late to produce mushrooms from that spawn. In that case, take note of these tips, and be better prepared next time.

Problem: Inoculated But No Fruit

When the inoculated medium never produces mushrooms, the first and most frequent solution to this problem is time. Some mushroom varieties can take a year or more to produce. It can be tough for the beginner to practice patience, but if you stagger cultivation over a couple of years, you will have regular flushes for years to come.

Several measures exist to speed things up, or to reinvigorate the mycelium (mushroom “roots”) if it seems to be slow to fruit. One is to moisturize. This includes misting logs, chips or other medium at least once a week—more during dry periods—and soaking logs in cold water for 24 hours. Another is proper airflow. Position logs outdoors in a well-ventilated area that gets air from as many directions as possible.

If growing indoors, keep a fan going or open windows to ensure airflow throughout the room. It’s helpful, although not absolutely necessary, to moisten the spawn and growing medium before inoculating. You could also moisten the growing medium directly after inoculating to help things move along faster and prevent the spawn from drying out.

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Another potential factor is contaminated spawn. Avoid this by careful handling. Wash your hands before handling spawn and after taking breaks from inoculation. Don’t let the spawn contact any surface but the medium you plan on inoculating, and avoid handling it while sick. All manner of bacteria exist on the human body and in the environment that can potentially contaminate your spawn, taking over before the mycelium has a chance to achieve dominance.

If possible, pasteurize your growing medium before inoculating. Generally, you will do this only with straw. Heat it up just enough to remove all harmful bacteria but keep beneficial bacteria alive. Sterilization—through chemicals or very high heat or pressure—will kill all bacteria, leaving an opening for bad bacteria to take over quickly. The ideal pasteurization temperature is between 160 and 180 degrees F. Heat water to 160 to 170 degrees, maintain this temperature and soak the straw in the water for one hour.

Susie Wyshak/Flickr.jpg

Problem: Growing Mycelium But No Fruit

If, upon examining your logs or other medium, you notice white fibrous materials, your spawn has successfully begun producing mycelium. It can still be some time before mushrooms arrive. If they never do, or if they start to form but abort, you might have used a bad strain or mismatched the strain and growing medium. In the former case, choose a different strain the next time around; in the latter, research carefully to ensure you use the most appropriate medium. Don’t confuse very small mushrooms, or pins, with aborted mushrooms. Often, you will only see pins well before you achieve full growth.

Problem: Substrate Not Producing

Be sure you understand the optimal region for the strain you order and the growing life cycle before determining that you have a growing problem. The three main designations of each strain’s ideal growing conditions are “warm weather,” “cold weather” and “wide range.” These indicate when they’re likely to fruit rather than the environment in which they grow best. In other words, if you live in a moderately temperate region, you can plant all three strains for staggered harvesting.

Wide range strains should produce in midsummer, late fall or early spring—depending on how northerly or southerly your climate is; cold weather strains will produce in early spring and late fall in northerly climates and most of the winter in southerly climates; and warm weather strains generally produce from midsummer to early fall in most climates. The easiest solution to mushrooms that are slow to produce is patience.

Problem: Deformities

Long stems, underdeveloped or cracked caps, “fuzzy feet” and other deformities can result from inadequate lighting, too much moisture or poor airflow. The vast majority of mushrooms need some degree of diffused light to grow. As the fruit grows, it will turn toward light.

A poorly lit area will cause the stem to grow too long as it tries to point the cap, which will stay small and narrow, toward light. Too much moisture or not enough moisture can also cause deformities. Don’t allow logs to sit in pools of water or place any medium in an area that stays consistently moist.

Moisture is good for mushrooms but you must give it an opportunity to evaporate. If moisture is inadequate, mushrooms might produce but will be dry and brittle with cracked caps. Add more and consistent moisture if you encounter this. As with any other part of the process, good airflow is important to avoiding deformities. Mushrooms like high CO2 environments and will develop fuzzy feet with a lack of fresh air.

Jereme Zimmerman

Problem: Spoiling Quickly After Harvest

Late harvesting can cause spoiling. Use late-harvested mushrooms quickly or avoid harvesting late. Most mushrooms are ideally harvested when their caps are still downturned and while dry. Avoid harvesting wet mushrooms.

If packaging and selling mushrooms at a farmers market, chill them before packaging. Package them in breathable containers covered in cellophane or an anticondensate greenhouse film.

These are the primary problems you might encounter when growing mushrooms. You probably won’t encounter all—or any—of them if you have carefully followed all appropriate steps. Always research the proper technique, growing medium and environment for each type of mushroom you grow. Most of the work in growing mushrooms is performed by time. All you have to do is get things started and wait for that first harvest (and many more) of delicious gourmet mushrooms.

This story originally appeared in the November/December 2017 issue of Hobby Farms.

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