Microsorum spectrum aka Triploid Fern

Microsorum spectrum is a challenging fern to grow, requiring specific conditions to thrive. It needs consistently high humidity (ideally 60-80%), pure water such as rainwater or distilled water, and careful attention to avoid overwatering while keeping the substrate moist. The species is slow-growing and sensitive to environmental stress, making it best suited for experienced growers or those with greenhouse or terrarium setups.

Microsorum spectrum requires high humidity levels to thrive, ideally 60-80% or higher. In its native Hawaiian rainforest habitat, it experiences consistently moist conditions. When grown indoors, use a humidifier, mist frequently (2-3 times daily), place the pot on a tray of wet pebbles, or grow in a terrarium or enclosed greenhouse environment to maintain adequate moisture levels.

Microsorum spectrum thrives in warm tropical conditions between 18-28°C (65-82°F). As a Hawaiian endemic fern, it cannot tolerate cold temperatures and should never be exposed to temperatures below 15°C (59°F) for extended periods. Frost will cause severe damage or death. If growing in cooler climates, maintain warm indoor temperatures year-round and avoid cold drafts.

Microsorum spectrum can be propagated through rhizome division or spore propagation. For rhizome division, select healthy sections with 2-4 fronds and cut below a node using a clean blade. Keep newly divided plants in shaded, warm conditions under plastic cover. Spore propagation is possible but requires controlled greenhouse conditions with high humidity and bottom heat, and produces variable frond morphologies.

Microsorum spectrum is a fairly compact fern with slow growth. Individual fronds typically measure less than 22 cm (9 inches) in length, though the variety pentadactylum can produce fronds exceeding 35 cm (14 inches). The fern spreads via slender, creeping rhizomes that prefer deep containers. Due to its slow growth rate, expect gradual development over months to years rather than rapid expansion.

Microsorum spectrum can only be grown outdoors year-round in tropical climates like its native Hawaii (USDA zones 10-11 or warmer). It requires consistently warm temperatures above 15°C (59°F), high humidity, and protection from direct sunlight. In subtropical or temperate regions, it must be grown indoors or in a heated greenhouse. If growing outdoors in suitable climates, provide a shaded location with moist, well-draining substrate and protection from wind.

Microsorum spectrum is susceptible to thrips, aphids, scale insects, mealybugs, slugs, and snails. Inspect fronds regularly, especially the undersides, for signs of infestation. Common diseases include root rot from overwatering, leaf spot, and botrytis in overly humid conditions without adequate air circulation. Treat pest infestations with insecticidal soap, neem oil, or manual removal with alcohol-dipped cotton swabs. Prevent root rot by ensuring excellent drainage and allowing the substrate surface to dry slightly between waterings.

Two varieties of Microsorum spectrum are recognized. The typical variety spectrum has simpler frond morphology and is found across the major Hawaiian Islands. The variety pentadactylum, restricted to Kauai, features more prominently three-to-five-lobed fronds with a distinctive ivy or sweetgum-leaf appearance, and can produce longer fronds exceeding 35 cm (14 inches). Both varieties share the characteristic fragrance and are critically endangered.

Microsorum spectrum is renowned for its distinctive fragrance, which is central to its cultural significance in Hawaiian traditions. The scent is often described as reminiscent of maile (Alyxia stellata) with notes of vanilla and light almond. The fragrance intensifies as fronds age. Traditionally, Hawaiians prized this scent for perfuming kapa (bark cloth) and coconut oil. However, some cultivators report difficulty detecting fragrance in cultivated specimens, suggesting environmental factors may influence scent production.

Repot Microsorum spectrum every 2-3 years or when rhizomes begin to outgrow the container. Choose deep pots to accommodate the spreading rhizomes and use a well-draining substrate such as New Zealand tree fern fiber, sphagnum moss, or a mix of peat, leaf mold, and sand with added charcoal. Handle the shallow root system gently during repotting and avoid disturbing rhizomes more than necessary. Repot in spring when active growth resumes.

Microsorum spectrum requires minimal pruning. Remove dead, yellowing, or damaged fronds by cutting them at the base near the rhizome using clean, sharp scissors. This encourages new growth and prevents pest and disease problems from developing on decaying plant material. Avoid cutting healthy fronds as the slow-growing plant benefits from every leaf for photosynthesis. Always sterilize cutting tools between plants to prevent disease transmission.

Clean Microsorum spectrum fronds gently by misting with pure water or wiping with a soft, damp cloth. Avoid using commercial leaf shine products which can clog pores and damage delicate fern fronds. Regular misting for humidity also helps keep fronds clean and dust-free. If pest infestations occur, wipe affected fronds with a cotton swab dipped in diluted rubbing alcohol or insecticidal soap solution.

Triploid Fern’s native range is Temperate and Tropical Old World.

Triploid Fern should be watered regularly, allowing the soil to dry out between waterings.

Triploid Fern requires special care to keep it thriving. Its sensitivity to dry soil means that you need to be especially careful when it comes to selecting the right potting soil. Look for a soil that will retain moisture, but is also well-draining. A good potting soil should have plenty of organic material, such as coco coir or sphagnum moss, which will help to keep the soil moist and provide extra nutrition for your plant. When planting your Peahi, make sure to mix the soil with some compost or manure to give it an extra boost of nutrients. Additionally, you should water your plant often to ensure that the soil remains moist. With the right care and attention, your Triploid Fern will bloom beautifully in your home.

Triploid Fern can survive in low light conditions, making them ideal for rooms that are far from windows or other light sources. However, for best results, place the plant less than 6 feet from a south-facing window to ensure it receives enough light.

Repotting the Triploid Fern is necessary either when it has doubled in size or once every year, whichever happens first. With fresh potting soil replenished annually, the plant will receive all the necessary nutrients, rendering the use of fertilizer unnecessary. Keep in mind that the source of a plant's energy is the sun, not fertilizer.

The toxicity level of this plant has not been officially confirmed by Ploi. If there is a possibility of ingestion of plant material with an uncertain toxicity by you, a family member, or a pet, it is advisable to seek the assistance of a medical professional.