Boston fern, Calathea, and prayer plant all get lumped into the "needs humidity" category — and that's true, but they're not the same plant. One will die if its soil dries out for a single weekend. One is most sensitive to water quality. One folds its leaves at night and is relatively forgiving of brief dry spells. Here's how they actually differ.
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Why this comparison matters
"High-humidity plant" is nearly as vague as "low-light plant." The term covers plants with meaningfully different thresholds and failure modes. Boston fern and Calathea appear in the same humidity roundups, but Boston fern's moist-soil requirement is more severe — it's the only one of the three that NC State says soil should "never be allowed to dry out." Calathea and prayer plant are more forgiving of brief dryness in the soil but are acutely sensitive to water quality and ambient humidity.
There's also a practical upside that most comparison articles skip: all three are confirmed non-toxic to pets by the ASPCA. For households looking for high-humidity plants that are also cat- and dog-safe, this group is one of the best options available.
What they are (botanically)
Boston fern — Nephrolepis exaltata (L.) Schott — is native to Tropical and Subtropical America, a naturally epiphytic fern in subtropical biomes per Kew POWO. Family Polypodiaceae. The "Boston" cultivar (N. exaltata bostoniensis) is the most common sold as a houseplant. It produces graceful, arching fronds 2–3 ft long with pinnately compound leaflets.
Calathea / Goeppertia — Most plants sold as "Calathea" have been reclassified into Goeppertia Nees per Kew POWO's 2020+ taxonomy, though the trade name "Calathea" remains in overwhelming use. Common example: Goeppertia makoyana (É.Morren) Borchs. & S.Suárez, formerly Calathea makoyana, native to Brazil (Espírito Santo) per Kew POWO. Family Marantaceae. Known for dramatically patterned foliage and nyctinasty — leaves fold upward at night via a pulvinus at the base of each leaf blade.
Prayer plant — Maranta leuconeura É.Morren — is native to Central and Eastern Brazil per Kew POWO. Family Marantaceae. Shares the same nyctinastic behavior as Calathea; the common name "prayer plant" comes from the leaves folding upward like praying hands at night. It has distinctive red fishbone-patterned veins, a low spreading growth habit, and short rhizomatous stems.
Side-by-side care table
| Need | Boston fern (Nephrolepis exaltata) | Calathea / Goeppertia | Prayer plant (Maranta leuconeura) |
|---|---|---|---|
| Light | Partial shade to bright indirect (NC State) | Medium to low indirect light (NC State) | Bright indirect to medium light (NC State) |
| Watering | Keep moist; never allow to dry out (NC State) | Moist, well-drained; not soggy; avoid tap water (NC State) | Evenly moist in growing season; reduce in winter (NC State) |
| Humidity | High; tolerates bathroom/kitchen conditions | High; tap water causes brown tips (Iowa State) | High; "intolerant of low humidity" (NC State) |
| Temperature | Average indoor warmth | 65–75°F preferred (NC State) | Average indoor warmth; no cold drafts |
| Soil | High moisture-retention potting mix | Moist, well-drained, rich potting mix (NC State) | Evenly moist potting mix |
| Water quality | Average; fluoride tip burn possible | Distilled or rainwater recommended to avoid tip burn (NC State) | Sensitive to fluoride/chlorine in tap water (Iowa State) |
| Difficulty | Moderate | Moderate-high | Moderate |
| Pet safety | Non-toxic (ASPCA) | Non-toxic (ASPCA) | Non-toxic (ASPCA) |
Boston fern care in depth
NC State states it directly: "This fern needs high humidity and moist soil that should never be allowed to dry out." Boston fern's epiphytic origins mean it evolved in humid tropical environments with consistent moisture. Unlike the other two plants in this comparison, brief soil dryness is not just inconvenient — it causes rapid frond browning and shedding.
NC State specifically recommends placing Boston fern "near kitchens and bathrooms for higher humidity or set on a tray of wet pebbles." This is one of the few cases where a primary extension source explicitly endorses bathroom placement. Boston fern also responds poorly to dry air: NC State notes that scales and spider mites become problems when air is too dry.
Scales and spider mites are manageable, but Boston fern's sensitivity to both soil dryness and low ambient humidity makes it the most demanding of the three in terms of consistent environmental conditions.
Calathea / Goeppertia care in depth
NC State Plant Toolbox for Goeppertia provides the authoritative care guidance: medium to low indirect light; moist, well-drained, rich potting mix (never soggy); high humidity; 65–75°F temperature range; and — critically — distilled or rainwater is recommended. Tap water fluoride and chlorine cause the notorious brown leaf tips that make Calathea a frustrating plant for new growers.
The temperature window of 65–75°F is specific and useful — per NC State, this is the preferred range. Cold drafts from windows or air conditioning vents, or temperatures that dip below this range at night, cause additional leaf stress beyond the humidity issue.
Iowa State Extension confirms that Calathea and prayer plants are both sensitive to fluoride and chlorine in tap water, which causes brown leaf tips. Using filtered, distilled, or collected rainwater for all watering is the most reliable way to prevent this damage.
The reclassification from Calathea to Goeppertia is a taxonomic update, not a care change. The ASPCA database still lists the genus as Calathea for its non-toxicity classification; the NC State toolbox uses Goeppertia for the care page. Both refer to the same group of plants sold commercially as "Calathea."
Prayer plant care in depth
NC State describes prayer plant as "intolerant of low humidity" and recommends placing it "in a humidified room or in a pot standing in a tray of wet pebbles as it requires high humidity." Unlike Boston fern, however, prayer plant tolerates some variation in soil moisture: NC State recommends keeping the potting soil evenly moist throughout the growing season but holding back in winter to allow the soil to dry out in the winter months.
This seasonal adjustment distinguishes prayer plant from Boston fern — prayer plant naturally rests in winter and can tolerate a slightly drier soil period. Boston fern cannot.
Maranta's low, spreading growth habit is also distinctive. NC State notes the plant "will spread horizontally" with short rhizomatous stems and that new leaves "appear as a rolled tube." The red fishbone-patterned veins on M. leuconeura are a clear identification feature — no other plant in this comparison group has this pattern.
Pet toxicity
All three are confirmed non-toxic by the ASPCA:
- Boston fern (Nephrolepis exaltata bostoniensis): Non-toxic to dogs and cats
- Calathea (Calathea spp.): Non-toxic to cats and dogs
- Prayer plant (Marantaceae family): Non-toxic to cats and dogs
This makes all three strong candidates for pet households seeking high-humidity plants. For contrast: the other popular high-humidity plants — peace lily and pothos — are both toxic to cats and dogs per ASPCA.
The ASPCA's non-toxic classification means no serious systemic effects are expected from typical ingestion amounts. It does not mean plants are edible or that GI upset from eating plant material in quantity is impossible.
How to tell them apart
Boston fern: Arching, feathery fronds 2–3 ft long with many small leaflets. NC State describes fronds as "graceful, green, have a lacy look." No distinctive leaf patterning — purely green. Growth is upright and arching from a central crown, not spreading.
Calathea / Goeppertia: Bold patterned foliage — species vary widely, but patterns include stripes, spots, and color contrasts on the upper leaf surface, often with purple or burgundy undersides. Upright clumping growth with longer petioles. Leaves fold upward at night. Many species reach 1–2 ft in height.
Prayer plant: Lower-growing and more spreading than Calathea. The distinctive red fishbone-patterned veins on the midrib are the clearest identification feature. NC State describes the veins as "prominent red fishbone-patterned veins, pale central variegation." Leaves fold upward at night via the same pulvinus mechanism as Calathea, which is where the common name comes from.
Which one should you get?
Get Boston fern if: You have a bathroom, kitchen, or laundry room with naturally elevated humidity and adequate indirect light. It's the most rewarding visually when it's happy — full, cascading fronds look dramatic in a hanging basket — but it punishes any lapse in moisture more severely than the others.
Get Calathea/Goeppertia if: You want patterned, decorative foliage that's also pet-safe. Be prepared to switch to distilled or rainwater and keep it away from drafts. The 65–75°F temperature range and water quality sensitivity are the two most common failure points per NC State.
Get prayer plant if: You want something similar to Calathea but with a lower growing, spreading habit and the distinctive red fishbone veins of Maranta leuconeura. It is the most tolerant of the three for occasional winter dryness and is confirmed non-toxic by ASPCA.
Use filtered water for all three — tap water fluoride and chlorine cause brown leaf tips in both Calathea and prayer plant per Iowa State Extension. Boston fern is less water-quality-sensitive but benefits from the same practice.
Frequently asked
Why do my Calathea leaves have brown tips?
The most common cause is tap water fluoride or chlorine. Iowa State Extension confirms that Calathea and prayer plants are sensitive to fluoride and chlorine in tap water, which causes brown leaf tips. NC State Plant Toolbox for Goeppertia specifically recommends avoiding tap water and using distilled or rainwater. Low ambient humidity is the second most common cause. Both problems often occur simultaneously, which is why bathroom placement helps — if the water quality issue is also addressed.
Is Boston fern safe for cats and dogs?
Yes. ASPCA lists Boston fern (Nephrolepis exaltata bostoniensis) as non-toxic to dogs and cats. It is one of the more widely available confirmed-safe plants for pet households that also provides visual interest. Non-toxic in ASPCA terms means no serious systemic toxicity from typical ingestion — it doesn't mean unlimited consumption is without consequence.
Do Calathea and prayer plant actually fold their leaves at night?
Yes — both exhibit nyctinasty, the movement of leaves in response to changes in light. The folding mechanism in both plants relies on a pulvinus — a specialized joint at the base of each leaf blade that expands and contracts with changes in water pressure. NC State notes new Maranta leaves "appear as a rolled tube" and that the prayer-plant name comes from the folding posture. This is a normal physiological behavior, not a sign of stress. If the leaves stop folding, that's usually a sign of insufficient light or poor plant health.
Sources: Kew POWO — Nephrolepis exaltata · Kew POWO — Goeppertia makoyana · Kew POWO — Maranta leuconeura · NC State — Nephrolepis exaltata · NC State — Goeppertia · NC State — Maranta leuconeura · ASPCA — Boston Fern · ASPCA — Calathea · ASPCA — Prayer Plant · Iowa State Extension — Diagnosing Houseplant Problems: Environmental Conditions