Black Witches' Butter Care (Exidia glandulosa)

This wood-inhabiting jelly fungus prefers cool, shaded woodland light rather than direct sun.

• Provide dappled or full shade with no more than 1–2 hours of weak early-morning sun; avoid any direct midday or afternoon sun, which can dry and toughen the fruiting bodies.
• Black Witches' Butter forms best on shaded, north- or east-facing logs where it receives indirect light all day and remains moist.
• In summer, protect host wood from exposure that raises surface temperatures or causes rapid drying; in winter, low light is acceptable as long as moisture is maintained.

This fungus depends on consistently moist wood rather than direct watering of the fruiting bodies.

• Maintain host logs or branches in humus-rich, well-drained woodland soil that stays evenly moist but not waterlogged; avoid standing water around the base.
• Before re-wetting cut wood, check that the outer 2–5 cm feel just starting to dry, then soak or thoroughly hose until the wood is evenly moist again.
• Shriveled, hard Exidia glandulosa that swells and becomes gelatinous after rain indicates previous dryness; persistent soggy, rotting wood with foul odor suggests chronic over-saturation.

This species is adapted to cool, temperate woodland climates with broad seasonal variation.

• Optimal active growth usually occurs around 40–65°F (4–18°C), common in moist autumn and winter conditions in many temperate forests.
• It tolerates a broad annual range of roughly 20–80°F (-7–27°C); short frosts may pause activity but rarely kill the organism within the wood.
• Extended heat above 80–85°F (27–29°C), especially combined with drying winds and sun, reduces visible fruiting; shelter host wood in cooler, shaded, humid microsites during hot spells.

This fungus prefers consistently moist, humid conditions rather than dry air.

• Aim for 70–90% humidity, similar to a shaded, damp woodland environment.
• Dry air causes shriveling, tougher rubbery texture, and reduced or halted new jelly-like growth.
• Increase humidity by placing culture containers in a closed, ventilated terrarium box with damp sphagnum or by misting nearby surfaces, not the fruiting bodies directly.

This wood-decay fungus is not grown in conventional soil but on suitable woody substrates.

• Use well-rotted hardwood logs or thick branches with high organic matter instead of soil, as Exidia glandulosa digests dead wood.
• Ensure the log drains freely and does not sit in standing water, because prolonged submersion limits oxygen and slows colonization.
• Maintain slightly acidic conditions (around pH 5–6.5) by avoiding lime-treated timber or heavy ash contamination on the wood surface.
• To improve aeration, raise logs off bare ground on bricks or racks so air can move around and excess moisture drains away.

This species is generally unsuitable for traditional container growing, as it requires colonized wood rather than potting media.

Exidia glandulosa (black witches' butter) fruits on nutrient-poor dead wood and generally does not need additional fertilizer.

Exidia glandulosa itself is not pruned; any management focuses on the host wood it grows on.

• Carry out any pruning of the supporting tree or log in late winter or after main fungal fruiting has finished.
• Remove only dead, unsafe, or badly damaged branches that host the fungus, using clean, sharp saws or loppers.
• Avoid cutting away colonized wood unless needed for safety, as this removes the substrate the fungus requires.
• Shape or thin surrounding vegetation rather than the fungus to improve light and airflow around the site.

This wood-inhabiting jelly fungus is not suited to normal repotting and behaves more like a decomposer than a potted plant.

• Transplant only if moving colonized logs or branches, not the fungus alone, since it depends on the wood substrate.
• Shift logs in cool, moist weather to reduce drying stress on the mycelium inside the wood.
• Place the new log location in partial shade with stable moisture so the wood does not desiccate quickly.
• Avoid frequent moving; instead, allow the colonized wood to remain undisturbed for several years.

Propagation of Exidia glandulosa is specialized and usually left to natural spore spread rather than home methods.

• In nature, the fungus reproduces from spores released from mature jelly fruiting bodies in cool, damp weather.
• To encourage spread, keep colonized hardwood branches in a shaded, moist, but well-ventilated area outdoors.
• Position fresh, uncolonized hardwood close to existing fruiting logs so airborne spores can land and infect new substrate.
• Avoid disinfectants or fungicides near the site, as these can suppress spore germination and mycelium growth.

This species is very cold hardy and typically needs no special winter care in the landscape.

• Fruit bodies often appear or persist in cool, wet winter conditions on dead hardwood.
• For container-grown wood sections, keep them outdoors in a shaded, moist spot rather than in a heated room.
• Avoid rapid drying by shielding logs from strong winter sun and wind while still allowing natural rain exposure.