Shiitake Log Cultivation: Is it Worth?

Today I want to write about something that come up again some days ago. It was the idea that you look at something and thing “hey that’s looks easy and can do that too” and then you jump. But then after digging a little bit deeper you conclude that it is way harder than you thought it is.

There is nothing wrong in jumping but 1) just because something looks form the outside easy doesn’t mean it’s the case and 2) starting something is easy but sticking to it, it’s not.

What has this to do with mushroom cultivation in general and with log cultivation in specific? From my perspective a lot. From the outside mushroom cultivation looks easy and especially when it comes to log cultivation.

The story I was referring to with my opening was a talk I had some time ago with a friend of mine who runs successfully a mushroom farm. During our talk he mentioned that he was thinking to start log cultivation. And the way he described it, it sounded easy but from what I read myself its actually not.

And coincidentally I just saw while I was thinking about this talk a video of my mentor who was interviewing someone who got into log cultivation. And while I was watching this interview, I realized more and more that this guy didn’t knew what he is up to when he first started.

And that’s why you are now reading this article. To get things straight. I don’t want to bash log cultivation. I have no reason to do so, but I think it is my obligate to inform those who want to start log cultivation so they can make better decisions.

Let’s start and see for yourself if log cultivation is something for you.

Step by Step

When it comes to log cultivation there are roughly 6 steps to go through in order to grow mushrooms successfully. These steps are

  1. Fell Trees for Bolts
  2. Inoculate Bolts
  3. Incubation Period
  4. Shock or Force Bolts
  5. Fruit and Harvest Shiitake => Process and Sell Shiitake
  6. Repeat step 3 to 5

Figure 1 gives you a quick overview over the process itself.

Figure 1: Process of shiitake cultivation on logs

Figure 1: Process of shiitake cultivation on logs[1]

Step 1 Fell Trees for Bolts

Like with every other mushroom cultivation technique everything starts with the substrate. The substrate you have a hand determines what mushroom strain you will in the end use. I grabbed a nice overview form the Mushroom Growers’ Handbook (Table 1).

Table 1: Trees suitable for growing shiitake

Table 1: Trees suitable for growing shiitake[2].                       

After you got familiar with the tree at hand you have to think about the time when you will fell the trees or if you by them when you should by them. According to what I read the majority recommend that the trees for log cultivation should be felled in winter or in spring.

Step 2 Inoculate Bolts

Now that you have your logs it is time to think about your mushroom strain. In this article I will only focus on the cultivation of shiitake. Before you choose your favored strain please keep in mind that strains used for natural log cultivation are different form strains that are used for sawdust bag cultivation!

One more time

“Strains used for natural log cultivation are different form strains that are used for sawdust bag cultivation!”

I can’t stress this point enough because from what I read many first-time mushroom farmers picked the wrong strain because they didn’t know it and even worst that the people from which they buy the strain didn’t inform them about this difference.

The consequence was that many of these first-timer lost all their logs.

If you are just starting out, then you should preferable choose a high temperature strains. The main reason for that is that high temperature strains are more sensitive to physical shocks. Which I will talk about in step 4.

High temperature strains are not only more sensitive to physical shocks, but their incubation period is shorter (see table 2). And that is a good thing. 1) get faster to market and make money, and 2) and more importantly you as a first-timer get faster feedback what worked and what not.

Table 2: Properties of shiitake strains (Summary)

Table 2: Properties of shiitake strains (Summary)[3].

After you have pick your strain than it is time to inoculate your logs. The logs should be inoculated anytime between one day and three weeks after the tree is felled – the sooner the better.

You can inoculate them with sawdust spawn, plug spawn, or thumb spawn. Each of them has their own advantages and disadvantages …

The process of inoculation is quite simple. You just drill hole into your log (figure 2), place your spawn into the hole and close everything with wax to protect the spawn. And here we come to the first bottleneck of log cultivation.

From what I saw every hole is made manually (30 – 40 hole per log). And with the 800 logs (see part 3) you will end up drilling 32,000 holes by hand. Because of that you will spend hours of just drilling.

Figure 2: Patterns of drilling and mycelial growth. A: Typical arrangement of holes, B: Growth patterns of shiitake in a log (bolt)

Figure 2: Patterns of drilling and mycelial growth. A: Typical arrangement of holes, B: Growth patterns of shiitake in a log (bolt)[4].

Step 3 Incubation Period

After you have inoculated the logs (now called bolts) and stack them together, the incubation period starts. This period can last between 8- to 18 months. During this time the humidity should stay between 75% and 100%. A drop of the humidity over a longer period will have a negative impact on your yield.

The recommended temperature range is 22°C to 26°C, with an optimum between 25°C and 30°C[5]. For that reason, shade cloths are used.

Step 4 Forcing Bolts

Now comes one of the more critical phases – the forcing phase. The question is when to start shocking? Which means when do you know that the incubation period is over.

To get a first idea it would make sense to see if we find any relationship between incubation period and yield. And there is one. If you look at the following figure 3 you will notice that the longer you wait the higher the yield.

Even though the is a lot of variance going on which give the impression that you can start earlier to shock you bolts it’s recommended to wait at least 14 to 16 months.

Figure 3: Spawn run length

Figure 3: Spawn run length[6]

Besides the relationship between incubation period and yield there are other signals that can tell you more about the “perfect” timing to shock you bolts.

  • When mycelium is visible on most of the bolt end (not all logs might have white mycelium).
  • Smaller diameter logs and warm weather spawn run earlier than larger logs and cold weather strains.
  • Night-time temperature avg. > 50°F (10°C).
  • When the logs lost 30% of their weight[7].

Now that you know when to shock the question arises how to shock? I found the following five methods which helps to initiate the pinning.

  • Place the logs in the coldest water available.
  • Keep the tank out of the sun.
  • Submerge in water for 24h.
  • Stack them together in A-frame.
  • Cover the logs.

The way you do the shocking will have an impact on the number of fruiting bodies per log (see table 3).

Table 3: Effect of beating and soaking the logs on fruiting body yield

Table 3: Effect of beating and soaking the logs on fruiting body yield[8].

After the shock the bolts were placed in an A-shape arrangement. The pinning itself will begin 3 to 5 days later.

Step 5 Harvesting Shiitake

Shiitake mushrooms are usually ready to be harvested 7 to 10 days after shocking, depending on the temperature. The higher the temperature the faster and vice versa. If you have done everything correctly you will be rewarded with a yield of 0.25 to 0.5 pound per log in the first year and 3 to 4 pound per log in the 2nd to 5th year.

After the fruiting the logs need to be rested for 6 to 8 weeks. Some will wait until 12 weeks. Then they will shock the bolts again and the pinning starts again. If you follow this cycle you will end with up to 3 flushes per log per year.

What are your thoughts about log cultivation? Do you think it is worth it?

The other two parts of this series can be found below.

Article 2 Bag Cultivation: The Holy Grail?

Article 3 Log Cultivation: Is it worth it?

[1] Mushroom Growers’ Handbook 2

[2] Mushroom Growers’ Handbook 2

[3] Mushroom Growers’ Handbook 2

[4] Mushroom Growers’ Handbook 2

[5] Mushroom Growers’ Handbook 2

[6] Northeast Share

[7] Mushroom Growers’ Handbook 2

[8] Mushroom Growers’ Handbook 2

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