How to Grow Lichen: A Step-by-Step Cultivation Guide

Growing lichen is possible, but it demands a fundamentally different mindset from growing plants. Lichens are not single organisms but symbiotic partnerships between fungi and photosynthetic algae or cyanobacteria, and coaxing those partners to cooperate outside their natural habitat is one of the more challenging projects in amateur and professional biology alike. The timescales alone can be humbling: visible growth from fragments may take many months, and full resynthesis from isolated components in a lab setting can require three months or more just to see the first tiny structures form. Still, researchers have refined workable methods over the past several decades, and hobbyists with patience can adapt some of these techniques at home.

Why Lichens Are Not Like Plants

The first thing to understand is that you are not growing one organism. A lichen is at minimum a fungus (called the mycobiont) living in intimate association with a photosynthetic partner, either a green alga or a cyanobacterium (the photobiont). The fungus provides structure and protection; the photobiont provides sugars through photosynthesis. Some lichens harbor additional partners, including yeasts discovered relatively recently. This composite nature is the reason lichens are so difficult to cultivate: you can grow the fungal partner alone, or the algal partner alone, but neither one will look or behave like a lichen by itself. Getting them to reassemble into a functioning lichen thallus in artificial conditions is the real challenge.

Scientists have been trying since the 1860s, when the dual nature of lichens was first recognized. Early attempts at resynthesis almost universally failed because the theoretical and experimental foundations simply did not exist yet. Successful reconstruction from separate components was only achieved decades later, once researchers understood the biology of each partner and developed methods for growing them in pure culture on artificial media.¹ That historical difficulty should recalibrate your expectations: even professionals find this hard.

Two Paths to Growing Lichen

You have two fundamentally different approaches, and which one makes sense depends on your goals and equipment.

• Fragment propagation: Take pieces of an existing lichen, including its natural vegetative dispersal units (called soredia or isidia), and transplant them onto a suitable surface where they can re-establish and grow. This is the more accessible route. It does not require sterile technique or lab equipment, and it works outdoors.
• Component isolation and resynthesis: Separate the fungal and algal partners, culture each independently in sterile conditions, then recombine them and hope they reassemble into a lichen. This requires microbiology equipment, sterile media, and considerable patience. It is mainly a research technique, though dedicated hobbyists with basic lab setups have attempted it.

Fragment propagation is where most people should start. Resynthesis is for those who want a deeper scientific challenge or who need to work with species that do not produce convenient vegetative propagules.

Growing Lichen from Fragments and Soredia

The simplest way to establish lichen in a new location is to use pieces that already contain both symbiotic partners. Many lichen species produce tiny vegetative structures, soredia (powdery clusters of fungal hyphae wrapped around algal cells) or isidia (small finger-like outgrowths from the thallus surface), specifically for dispersal. These are pre-packaged starter kits: each one contains everything needed to grow into a new lichen if conditions cooperate.

A study on three threatened epiphytic lichens demonstrated how this works in practice. Researchers placed small cotton gauze discs on tree bark and transferred vegetative diaspores onto them. All three species produced anchoring hyphae within the first month. The first lobes resembling adult thalli appeared after eight to twelve months in two species, and after sixteen months in a third. Over a thirty-two-month observation period, thalli reached up to three millimeters in length.² Three millimeters in nearly three years gives you a realistic sense of the pace.

For a practical home approach, collect small fragments or soredia from a healthy lichen colony (with appropriate permissions if on public land). The best time is during a period when the lichen is moist and actively metabolizing, typically after rain. Press the fragments gently onto a substrate that matches the lichen’s natural preference: rough-barked wood for epiphytic species, stone for saxicolous ones. Some growers blend fragments with a small amount of buttermilk or yogurt to create a slurry that adheres to vertical surfaces, though the scientific literature on this folk method is thin. What matters more than the adhesive is choosing the right surface and the right microclimate.

Research on the dispersal and survival of soredia and thallus fragments has shown that the microsite matters enormously. Establishment and survival rates vary depending on exactly where on a piece of bark the propagule lands, with crevices and textured areas offering better purchase than smooth surfaces.³ Tuck your fragments into grooves, crevices, or textured patches rather than placing them on flat, exposed surfaces.

Isolating the Fungal Partner

If you want to try resynthesis, you first need to grow the fungal partner in pure culture. The standard approach is spore discharge: you place a fertile lichen thallus (one bearing fruiting bodies) in a humid chamber above a petri dish of sterile agar. The fungus releases ascospores, which land on the medium and, with luck, germinate.

A large study working with over 200 lichen species found that crustose lichens had the highest spore discharge rates and the best germination percentages. Foliose lichens discharged spores readily but germinated less reliably. The most successful growth medium was 2% malt-yeast extract agar, a relatively simple recipe. The researchers also tested a novel approach using a sponge as a physical carrier in liquid culture, which showed considerable promise for growing mycobionts under static conditions.⁴

Even when spores germinate, growth is painfully slow. Lichen fungi in culture typically grow as tiny, featureless colonies that look nothing like the intact lichen. They often lack the distinctive chemistry of the parent organism: one study found that the mycobiont of Heterodea muelleri grown alone did not produce any detectable secondary metabolites, whereas the intact lichen produced diffractaic acid and barbatic acid.⁵ The fungus needs its algal partner to activate much of its chemical repertoire.

A comprehensive review of culture requirements for lichen-forming fungi has catalogued the nutritional and physicochemical needs for 110 species, giving researchers a reference point for media composition, pH, and temperature.⁶ If you are attempting this at home, malt-yeast extract agar at around 2% concentration is a reasonable starting point for many species.

Isolating the Algal Partner

The photobiont can be isolated separately, though it requires different techniques. One approach involves homogenizing a piece of lichen thallus and plating the resulting suspension onto a medium that favors algal growth while suppressing fungal contamination (often by adding antifungal agents). Researchers have also succeeded with a simpler thallus method that skips the homogenization step entirely, placing small pieces of thallus directly onto appropriate media and waiting for algal cells to grow out.⁷

Lichen photobionts are most commonly species of Trebouxia (green algae) or Nostoc (cyanobacteria), depending on the lichen. These grow more quickly in culture than the fungal partner and are generally easier to maintain. A brightly lit windowsill or a grow light providing moderate illumination can sustain algal cultures in simple mineral media. The algal partner is the less finicky half of the equation.

Putting the Partners Back Together

Resynthesis, the holy grail of lichen cultivation, means taking your separately cultured fungus and alga and getting them to form a functioning lichen thallus. This is where the difficulty escalates. Both partners need to be in the right physiological state, the environmental conditions need to mimic the stress that drives symbiosis formation, and the process takes months.

In one well-documented experiment, researchers co-cultured isolated fungal and algal partners of Usnea hakonensis for three months. The result was visible protrusions on the culture surface: tiny but recognizable thallus structures that confirmed the symbiosis had re-formed.⁸ Three months for small protrusions gives you a realistic benchmark. Full, mature-looking thalli take much longer.

The general protocol involves mixing fungal and algal cells together on a nutrient-poor medium (nutrient stress encourages the fungus to seek out the alga) and maintaining the culture under cycles of light and dark with periodic misting or humidity. Some researchers use membranes or filters as substrates to support the developing thallus. The conditions are deliberately kept somewhat harsh: rich media tend to let each partner grow independently, while lean conditions push them toward partnership.

Light, Moisture, and Substrate

Whether you are growing fragments outdoors or maintaining cultures indoors, three environmental factors dominate lichen success: light intensity, hydration cycling, and substrate chemistry.

Lichens generally do not need or want intense direct sunlight. Laboratory measurements of two epiphytic species, Lobaria pulmonaria and Platismatia glauca, found that their photosynthesis reached light saturation at just 100 to 150 micromoles of photons per square meter per second, and they hit the compensation point (where photosynthesis just barely exceeds respiration) at only 5 to 10 micromoles.⁹ For context, full outdoor sunlight is roughly 2,000 micromoles. Bright indirect light or dappled shade outdoors is perfectly adequate. Indoors, a standard fluorescent or LED grow light at moderate output will do the job, and keeping the light too close or too bright can actually harm the lichen by drying it out.

Hydration cycling is arguably more important than light intensity. Lichens are poikilohydric, meaning they cannot regulate their own water content the way vascular plants do. They absorb moisture directly from rain, fog, and humid air, and they dry out completely between wetting events. This drying-and-rewetting cycle is normal and necessary. A lichen kept perpetually wet will rot; one kept perpetually dry will go dormant and eventually die. If you are growing lichen outdoors, natural rainfall in a temperate climate usually provides adequate cycling. Indoors, misting once or twice a day with clean water and allowing the thallus to dry out between mistings mimics natural conditions.

Substrate matters because lichens physically interact with their growing surface. Rock-dwelling species, for instance, produce extensive root-like structures called rhizomorphs that penetrate and incorporate particles from the substrate. Research on two rock-colonizing lichens showed that rhizomorph hyphae pushed between substrate particles and, in the case of calcareous rock, chemically dissolved the matrix to gain purchase.¹⁰ Match your substrate to the species: bark for tree-dwelling lichens, calcareous stone for limestone species, acidic rock for granite colonizers. Using the wrong substrate is a common reason transplants fail.

Keeping Cultures Clean

Contamination is the nemesis of anyone trying to culture lichen components in the lab. Lichen thalli harbor a rich community of other fungi, bacteria, and yeasts beyond the primary mycobiont. If you do not sterilize the surface before attempting to isolate partners, your petri dish will be overrun with contaminants long before the slow-growing lichen fungus gets going.

A study testing different surface sterilization protocols for lichen thalli found that the most effective method involved a brief dip in 70% ethanol for ten seconds, followed by immersion in 0.5% commercial bleach for three minutes, and then three consecutive one-minute washes in sterile distilled water. This protocol yielded a 100% isolation rate with zero fungal growth on control tissue prints.¹¹ If you are working at home with limited equipment, this ethanol-bleach-rinse sequence is a practical baseline.

Even with good sterilization, expect some plates to become contaminated. Work near a flame or in a still-air box, transfer quickly, and prepare more plates than you think you need. Professional labs use laminar flow hoods, but a simple still-air box made from a clear plastic storage container can reduce airborne contamination enough for hobbyist work.

Scaling Up with Bioreactors

For those interested in producing lichen biomass or metabolites at larger scales, bioreactor culture of isolated mycobionts has shown dramatic improvements over static petri-dish growth. In one study, two Ramalina species were first grown in optimized flask cultures, where they each produced a few grams of biomass over sixty days. When the same optimized conditions were transferred to a bioreactor, R. nervulosa yielded roughly 17.7 grams of biomass in just four and a half days, and R. pacifica produced about 10.3 grams in the same timeframe.¹² The bioreactor biomass also produced substantial quantities of bioactive compounds like usnic acid and salazinic acid. This approach is not about growing intact lichen thalli; it is about farming the fungal partner rapidly for its chemical products. But it illustrates that lichen components can grow fast when freed from the constraints of the symbiosis and given ideal conditions.

Outdoor Restoration at Scale

If your goal is to establish lichen cover over a larger area, say on a garden wall, a restoration site, or a disturbed landscape, the fragment-slurry approach can be scaled up. Ecological restoration research has tested practical methods for re-establishing lichen-moss biocrust communities. In one multi-year field experiment, researchers applied moss and lichen fragments in a water slurry, sometimes with added clay and sometimes onto jute ground cloth laid over bare soil. After three to four years, moss and lichen cover on jute cloth was five to eight times higher than on bare ground. Plots that received lichen fragments specifically had about six times more lichen cover than those without.¹³

The jute cloth finding is worth paying attention to. The fabric provides a rough, moisture-retaining surface that gives fragments something to grip while they anchor. If you are trying to establish lichens on a smooth garden wall or a new concrete surface, providing some kind of textured underlayer, or at least roughening the surface, could substantially improve your success rate. Clay mixed into the slurry also seemed to help, likely by providing mineral particles that retain moisture and give developing hyphae something to bind onto.

Air Quality as a Hidden Limiting Factor

One reason lichen transplants fail in urban or suburban settings, even when light, moisture, and substrate seem right, is air pollution. Lichens are famously sensitive to atmospheric contaminants, and different species respond to different pollutants. Research in a Mediterranean urban area found that certain lichen functional groups, particularly those preferring low-nutrient, moist, acidic conditions, declined sharply near roads with heavy traffic. Other groups tolerant of nutrient enrichment and dry conditions were more common in polluted areas.¹⁴

Ammonia is a particularly damaging pollutant for sensitive species. Experimental exposure showed that in an ammonia-sensitive lichen (Flavoparmelia caperata), the gas degraded chlorophyll in the photobiont and damaged the cell membranes of the mycobiont, while a tolerant species (Xanthoria parietina) showed only mild photosynthetic effects.¹⁵ If you live near a busy road or an agricultural ammonia source, choose tolerant species for your cultivation attempts. The bright orange Xanthoria parietina, commonly found on rooftops and urban walls, is a good candidate for polluted environments precisely because of its resilience.

Storing Lichen Material for Later Use

Lichen fragments and cultures can be stored for remarkably long periods if handled correctly. A study on long-term storage found that desiccated lichen thalli kept at minus 20 degrees Celsius remained fully viable for up to thirteen years, with unchanged coloration and chlorophyll fluorescence. Even more extreme, thallus fragments of Xanthoria parietina grew normally after a week of storage in liquid nitrogen without any cryoprotectant.¹⁶

For practical purposes, this means you can collect lichen fragments during favorable conditions and store them dry in a freezer until you are ready to use them. Standard home freezer temperatures (around minus 18 to minus 20 degrees Celsius) fall right in the range shown to preserve viability. Let the fragments air-dry thoroughly before sealing them in an airtight container for freezer storage. When you are ready to use them, allow them to thaw and rehydrate gradually by misting with water. This approach is especially useful if you collect fragments during a trip to a natural area and want to transplant them weeks or months later in your own garden or on a studio project.

Working with Lichen Fragments in Culture

Between full outdoor transplanting and full aseptic resynthesis from isolated components, there is a middle path: growing lichen fragments in controlled laboratory-like conditions. Researchers have placed pieces of various lichens in culture and observed regeneration and developmental steps over time. Work with Cladonia fragments showed that the stages of podetial development (the upright, cup- or trumpet-shaped structures characteristic of the genus) were easily distinguishable and developed in a synchronized fashion over comparatively short periods.¹⁷ Fragment culture is a useful approach if you want to study lichen development without the full complexity of isolating and recombining partners. It also lets you observe regeneration in species that have been damaged, which can inform conservation or transplant strategies.

For a home setup, small lichen fragments can be placed on damp filter paper inside a covered petri dish or a clear container with ventilation holes. Keep the container in bright indirect light and mist periodically to maintain humidity without waterlogging. You will not see rapid growth, but over weeks to months you may observe the fragment extending new hyphae and, in some species, developing recognizable new structures at its margins. A magnifying glass or simple dissecting microscope makes the process much more rewarding, since the changes are often too small to appreciate with the naked eye.