How to Cultivate Morels: A Step-by-Step Guide

The cultivation of morel has fascinated mankind for more than 130 years. Many have tried to grow them outdoors as well as indoors. But they failed.

Now it seems that the Chinese found a method which is working – at least for the outdoor cultivation of morels. But new challenges are on the horizon.

These and more I want to address in today’s article.

Nutrition and Health benefits of Morels[1]

Why do you want to grow them anyway? Morels are a rare and delicious mushroom. They contain

tocopherols (α, ϒ, δ)
carotenoids (β, Lycopene)
organic acids (oxalic acid, malic acid, citric acid, fumaric acid, quinti acid)
phenolic compounds (protocatechnic acid, p-Hydroxybenzoic acid, p-Coumaric acid)

and they have

antimicrobial properties
anti-inflammatory properties
antioxidant potential
immunostimulatory
anti-tumor properties

Due to these factors, their market value is high and, therefore, attracts many people in trying to cultivate them artificially.

Why is it so tricky and What are morels anyway?

Morels were first thought to be saprobic[2]. Later studies found that some morels but not all have the ability to form a mycorrhizal relationship with a host in order to receive nutrients[3]. If you, therefore, choose the wrong morel species, you are prone to fail. Only nowadays, with the help of DNA sequencing, you can better select the right species. But still, then, there is no guarantee for success.

If you choose a morel species which is mycorrhizal, then you must emulate not only the environmental conditions but also the host

Host trees for Morels

In a 2010 published article, the authors interviewed morel hunters in America and collected information about the relationship between host trees and morels (Figure 1). According to their findings (tulip) poplar, elm, and ash are a good indicator to find morels.

While it seems that black morels can be found more often near (tulip) poplar. Yellow morels can be found more frequently near elm trees. Both morel types, as well as gray/white morels, can be found next to ash trees.

Figure 1: Frequency of mention of associations between morel types and tree species[4]

History of Morel Cultivation

As mentioned earlier, many have tried over the last 130 years to cultivate them because of their nutritional and health benefits as well as their high economic value. Here a quick overview of some milestones.

The first report on outdoor cultivation dates back in 1882[5].

1904 first successfully cultivation on apple compost was reported[6].

In 1982 Ower claimed success and filed a patent which was granted in 1989. But the commercial scale of indoor cultivation failed[7]. Ower was robbed and murdered in a park in San Francisco before the patent was filed[8].

1990 Neogen and Domino’s Pizza formed “Morel Mountain” claimed to produce 1,400 lb per week but closed in 1999[9].

Since 2008 there was no artificial cultivation taken place[10].

The Chinese started back in 1980s with the research. The first success was reported in 1994 by Zhu, which filed four patents (2001, 2007, 2009, and 2012)[11].

The cultivation of morels in China grow from 405 ha in 2011 to 9,470 ha in 2016[12].

The Natural Habitat of Morels

If you want to cultivate mushrooms of any kind, you have to understand their natural habitats. Therefore, many people went out and analyzed the morel bearing sites. Pilz summarized the findings in his 2007 released booklet and stated that “Morels can be found in all countries of the Northern Hemisphere that have temperate and boreal forests (forest with distinct cold season), in Mediterranean or subtropical Areas like California, in the Highlands of Mexico and Guatemala as well as in the Middle East[13]”.

Several other studies described the growth of morels in Jammu and Kashmir, Himachal Pradesh, and Uttaranchal[14].

Morels are also found in Chile and in Australia both in conjunction with eucalyptus[15].

According to Du, black morels are distributed in the cold temperature zone of the mountain, where the altitude is generally above 2,000 m. While the yellow morel can be found in the mountains below 1,200 m[16].

To summarize these statements, figure 2 provides us with a hypothesis of how morels spread throughout the world.

Figure 2: Hypothesis of place of origin, migration routes, and rapid radiation and speciation of morels[17].

What Soil Conditions do Morels need?

Because not all regions are created equally and therefore, morels don’t grow everywhere people starting to take a closer look at the composition of soil and the environment. They found that the soil should be sandy to loam with humus[18]. With the best yield of humus-rich sandy loam is yellow loam[19]. Besides, the soil should be of high aeration and porosity[20].

An interesting analysis did Singh in his study. He compared the soil underneath morels and some meters away from them where no morels could be found. Because I am a visual guy, I put his data in a graph (figure 3), which illustrates the difference in both areas better.

The bars in blue represent the values for the soil underneath the morels, while the orange bars represent the values of the soil away from them.

As we can (now) see, the soil underneath morels is rich in carbon and nitrogen, as well as sodium. In the same token, the electrical conductivity (EC) is high.

Areas without morels are high in phosphates, chlorides, potassium, and have a low EC.

Everything else is quite similar.

Figure 3: Elemental profile and soil ecology of morel bearing sites; carbon, nitrogen, and phosphates in percent; chloride, potassium, calcium, lead, sodium, and nitrates in ppm (blue: soil below the fruiting body, orange: soil away from the fruiting body)[21]

I found some more numbers in Manikandan’s article, where he analyzed the natural sizes in Himachal and Rajasthan[22].

Altitude 1,350 m

Texture Clay loam

Bulk density (Mg/m³) 1.33

Water holding capacity (%) 37.29

Organic carbon (%) 0.64 to 0.72

pH 7.82 to 7.86

Electric conductivity (dS/m) 0.76 to 0.81

Avg. N (kg/ha) 336.5 to 364.5

Avg. P (kg/ha) 9.82 to 15.04

Avg. K (kg/ha) 486.4 to 624.4

But these values can be misinterpreted or to be more precise misguiding. Why?

Morels will alter the soil composition throughout their growth. In which way, I will describe later more in detail.

Which Morels can be cultivated?

Now the more interesting part. Which morels can be cultivated? There are according to Pilz 196 morel species[23]. Of which 61 species can be found in East Asia or China[24], 23 species in Europe[25], and 19 species North America[26].

Out of all these species so far, four different types of morels are cultivated right now in China.

M. importuna
M. sextelata
M. septimelata
M. esculenta

With M. esculenta as the largest share of 95 %[27].

Morel Mushroom Life Cycle

An essential part of understanding morels better is to understand the life cycle of them (figure 4). The foundation of our understanding comes from Volk and Leonard[28]. Two of the most critical phases during the morel mushroom life cycle are sclerotia formation and conidia production[29].

I will spare you with my writings about the life cycle and refer directly to one of the sources – Pilz 2007.

Figure 4: Morchella life cycle[30]

Current development

After that introduction, let’s have a closer look at the ongoing development.

According to Liu, the commercial production of morels increased from 200 ha in 2011 to 1,200 ha in 2015[31]^,[32]. That means as I wrote earlier that the Chinese found a method which produces morels on a larger scale.

What the Chinese figured out is that by providing local sources of high nutrient morels will develop. This method is called the Exogenous Nutrient Bag (ENB) method[33].

With the ENB method, a mixture of wheat grain and rice husk as a nutrient source is laid on top of the beds (Figure 5). The mycelium growth into the ENB extract the nutrients and transfer them to the soil.

And here, the process of alteration of the soil composition starts.

Figure 5: Schematic diagram of ENB decomposition by M. importuna SCYDJ1-A1[34]

Why ENB seem to work?

As shown in figure 5, the mycelium enters the ENB and transfers nutrients to the beds. In doing so, the dry weight of the ENB drops during the cultivation period (figure 6). While at the same time, the fruiting body yield increases (figure 7).

Figure 6: Development of the dry weight of the ENB during the cultivation period[35]

Figure 7: Development of the fruiting body yield during the cultivation period with ENB[36]

According to Pilz, changes in the environment can trigger the primordia formation. Such triggers can be wildfires, tree death of forest disturbances[37]. Some of these triggers lead to loss of soil nutrient or flushes of readily available nutrients[38].

By providing the ENB, the mycelium has access to an abundant source of nutrients.

What’s in the bag?

If the ENB method works, then everybody wants to know “What’s in the bag?” While not many detail information is out there, we can still find hints right and left.

First, the sclerotia development. Alvarado-Castillo found that rye grains increased the mycelial growth by a factor of 3-5 over wheat grain (figure 8). He also found the physical barrier introduced by Ower leads to a smaller sclerotia weight[39].

Figure 8: Mycelial growth (cm²) of Morchella in different types of grain for five strains studied[40].

Second, the ENB itself. Tan describes the following compounds of the ENB[41].

Carbohydrates: Over 90 % of amylose was metabolized during the cultivation period, and 72 % of the amylopectin.
Lipids: While the lipase activity was the second-highest in ENB. The content of lipids was not. It is, therefore, hypothesized that lipids were synthesized and stored temporarily in the ENB.
Lignin: The decomposing started slowly during the 15-45 days after placing the ENB and increased during the period 45-75 days.
Nitrogen nutrition: Only slightly variation both in the ENB and the soil during the cultivation period.

To understand the impact of the ENB better, Qingya Liu analyzed the effects of elements complexes containing Fe, Zn, and Mn in ENB and found that the relationship between had an impact on the yield (Figure 9).

With the following trend: Zn-Fe > Mn > Zn > Zn-Mn > Fe-Mn > Zn-Fe-Mn > Fe > ck[42].

Figure 9: Morel yields of groups with different element treatments[43]

Step-by-Step Process to Grow Morels[44]

With everything you learned so far in mind, it is now time to go through the process of cultivating morels step by step.

Step 1: SPAWN PRODUCTION

Maternal spawn, A: Morel mycelium, is transferred on potato dextrose agar (PDA) and incubated at 15 °C for 15 days.
B: A 500 ml jar is filled with 400 cm³ of solid substrate (360 cm³ (90 %) of sandy loam soil and 40 cm³ (10 %) of logging debris). Autoclave the bottled substrate at 121°C for 2 hours.
Proto-Spawn: Transfer of 2 cm³ (0.5 %) of (A) into the mixture (B) and incubate at 15 °C for 20 days.
C: A 500 ml jar contains 400 cm³ of solid substrate (200 cm³ (50 %) of soaked wheat grains, 180 cm³ (45 %) of sandy loam soil, and 20 cm³ (5 %) of logging debris is filled in jars and autoclaved at 121°C for 2 hours.
Cultivating spawn: Transfer of 20 cm³ (5 %) of (B) into the mixture (C) and incubated at 15 °C for 20 days.

Qizheng Liu mentioned the following alternative recipe for spawn production[45].

wheat 46 %
husk 20 %
wheat bran 18 %
sawdust 10 %
gypsum 1 %
precipitated calcium carbonate (PCC) 1 %
humus 4 %

Step 2: PREPARING THE BEDS AND SOWING

Preparing the beds … Zhang mentioned 0.8 to 1.0m for the width of the ridge. 0.3 to 0.4 m for the width of the groove and a 0.2 to 0.3 m depth of the ditch. The height difference between the surface and the bottom of the groove is preferably 20~30 cm[46].
Sowing 400 g/m² of (C) on the prepared beds.
Covering the beds with a non-nutrient soil layer (1-2 cm) – casing.

Ge mentioned the adding of “calcium oxide or calcium carbonate (250 to 370 kg/ha) or plant ashes (1,000 to 1,240 kg/ha) to adjust the soil pH[47]”.

Step 3: ENB PREPARATION

Wheat grain (85 %) and rice husks (15 %) are soaked until soften
Mixing of the substrate
Filling of the mixture in bags (350 g) and autoclaving at 121 °C for 3 hours.

An alternative mixture for ENB is provided by Zhang[48].

85 % corncob (cotton seed shell, crop straw) fermented material
10 % wheat bran
4 % grass ash
1 % gypsum
Water content 60 %

Step 4: ENB PLACING

Both Tan and Zhang are putting holes in the bags before placing them onto the soil. The holes are facing downwards.
The ENB will be placed 15 days after the sowing.

Step 5: PRIMORDIAL FORMATION

Primordia formation starts four months after sowing
The soil moisture should be kept between 45 % and 60 % during the winter[49].
The temperature should be kept between 8 °C and 20 °C[50].

If we look at some hints about how to proceed further, we can found some in the writing of Pilz where he writes “Morels will fruit when winter snow is melted, the soil is beginning to warm, and the air is still humid[51]” and “Warmth and humidity provide the conditions morels need to continue development once they start fruiting[52]”.

Indoor cultivation of Morels

In his 2019 published master thesis, Ge investigated two types of experiments with the goal of cultivating morels indoors. These experiments had the following setups.

Experiment 1: 1 Morchella isolate, five different substrates, two nutrient bags.
Experiment 2: 4 Morchella isolates, two soil substrates, two nutrient bags

For the spawn production, he used the following recipes.

250 ml flasks

50 ml beaker level full of rye grain

½ tsp. Calcium Carbonate, powder (lime)

¼ tsp. Calcium Sulfate (gypsum)

60 ml warm water

The ingredients were mixed and autoclaved for 35 minutes at 121 °C.

1,000 ml flasks

250 ml beaker level full of rye grain

2 tsp. Calcium Carbonate, powder (lime)

1 tsp. Calcium Sulfate (gypsum)

220 ml warm water

The ingredients were mixed and autoclaved for 35 minutes at 121 °C. Which is in comparison with Tan way shorter (see step-by-step process).

Ge reported contamination during his two experiments with more contamination in the second experiment. Due to the lack of information, I, unfortunately, couldn’t figure out if there is any correlation between the contamination and the substrate mixture and or nutrient bag. Ge wrote that the reason could be the soil or raw materials.

I am not sure about that, because one of the main differences between these two experiments is, that during the second experiment the tubs were heavily watered with tap water at 55 dpi[53] (in analogy to the cultivation of shiitake) while the tubs in the first experiment didn’t receive this treatment.

As Zhang mentioned, “prevent flooding […] if the amount [of water] is too large it causes mycelium death[54]”. For me, this could be the reason for the failure.

Challenges of Morels Cultivation

While the outdoor cultivation of morel seems to be a success. It still is a challenge. As Alvardo-Castillo wrote in his paper, “the production of Morchella depends on the formation of sclerotia.[55]” If you don’t get the parameters right, you will fail.

Besides that, another challenge started in 2013, parallel with the establishment of the outdoor cultivation of M. importuna[56].

It is the raise of pileus rot disease and of a white mold. Several article can be found on this topic[57].

The stipe rot disease is caused by the Fusarium incarnatum-F. equiseti species while the white mold disease is caused by the Paecilomyces penicillatus[58].

But that is part of another article.

If you want to go deeper into the trenches, than you will find in the next section all the literature and some more I used for this article.