Growli Research · Data study
The frost-tender houseplant report — a third can't survive a freeze
More than a third of catalogued houseplant species — 2,044 of 5,472 zone-tagged plants — are rated hardy only to USDA zone 10 or warmer. They won't survive a hard outdoor freeze. Here is what the data reveals about the plants you bring inside every autumn.
Published 26 June 2026 · By the Growli editorial team
Key findings
- 36.8% of zone-tagged species are frost-tender (2,044 of 5,472). More than a third of catalogued houseplant species are rated hardy only to USDA zone 10 or warmer — they are not reliably frost-hardy and will not survive a sustained outdoor freeze. The 89 untagged species are excluded from this calculation, making 36.8% a conservative floor.
- A further 17.6% (984 species) are half-hardy at zone 9. Zone 9 plants tolerate light-to-moderate frost (20–30°F / −6.7 to −1.1°C) but are damaged or killed by hard freezes. Keeping them out of the 36.8% headline makes the frost-tender count conservative. If zone-9 half-hardy species were included, the combined frost-sensitive share would reach 54.4%.
- 43.9% of zone-tagged species (2,444) are rated zone 8 or colder. The cold-tolerant majority can withstand temperatures at or below 10°F (−12.2°C) and are genuinely outdoor-suitable across most of the UK and northern US without winter protection.
- Most bestseller houseplants are frost-tender tropicals. Monstera, pothos, philodendron, anthurium, peace lily, bird of paradise, Aglaonema, bromeliads and caladiums are all zone 10–12. They are sold as indoor plants in temperate climates precisely because they cannot tolerate any sustained outdoor frost.
Here is the hardiness-zone distribution across the catalogue.
| Zone band | Species (n) | Share of tagged | RHS equiv. | Cold limit |
|---|---|---|---|---|
| Zone 10–12 (frost-tender) | 2,044 | 36.8% | H1a–H2 | Above 30°F / −1.1°C |
| Zone 9 (half-hardy) | 984 | 17.6% | H3 | 20–30°F / −6.7 to −1.1°C |
| Zone 8 or colder (frost-hardy) | 2,444 | 43.9% | H4–H7 | Below 10°F / −12.2°C |
| Zone unknown (untagged) | 89 | 1.6% | — | — |
Methodology
gov, updated November 2023 reflecting 1991–2020 climate normals) and horticultural reference databases. 4%) carry a zone value; the remaining 89 are untagged and excluded from all percentage calculations. Definition: "frost-tender" = lowest survivable USDA hardiness zone is 10a or higher. 7°C), which straddles the 32°F (0°C) freezing point. The cleanest claim is "will not reliably survive a sustained outdoor freeze" rather than "cannot survive any frost" — a very brief, light radiation frost at 30–32°F may not immediately kill every zone-10a plant, but a hard freeze will.
1°C) species are classified half-hardy and kept outside the headline figure. USDA zones describe average annual extreme minimum temperatures for a location, not per-winter guarantees; the dataset value is the plant's rated minimum hardiness zone (what cold it can take), not where it is grown. uk): zone 10+ ~ H1a–H2 (tender), zone 9 ~ H3 (half-hardy), zone 8 and colder ~ H4–H7. Cold-damage physiology framing fact-checked against Clemson HGIC factsheet on cold damage, Iowa State Extension, and MSU Extension publications on protecting plants from cold temperatures.
Frequently asked questions
What percentage of houseplants are frost-tender?
In Growli's 2026 dataset of 5,561 plant species, 36.8% — 2,044 of the 5,472 species that carry a hardiness zone value — are frost-tender, defined as rated hardy only to USDA zone 10 or warmer (approximately 30–35°F / −1.1 to 1.7°C minimum). They will not survive a hard outdoor freeze. A further 17.6% (984 species) are half-hardy at zone 9, and 43.9% (2,444) can tolerate zone 8 or colder.
What does USDA zone 10 mean for a houseplant?
A plant rated USDA zone 10 is only reliably hardy in areas where the average annual extreme minimum temperature stays at or above 30–35°F (−1.1 to 1.7°C) — essentially frost-free climates such as coastal Florida, Hawaii, or southern California. In the UK and across most of the US, zone-10 plants must be brought indoors before the first autumn frost. They are sold as houseplants in temperate climates specifically because they cannot survive outdoors year-round.
Which popular houseplants are frost-tender?
The most common frost-tender houseplants (all zone 10–12) include monstera, pothos (Epipremnum aureum), peace lily (Spathiphyllum), anthurium, philodendron, bird of paradise (Strelitzia reginae), most palms, caladiums, bromeliads and Chinese evergreens (Aglaonema). These are sold as indoor plants in temperate climates precisely because they cannot tolerate frost.
How do I protect frost-tender plants in winter in the UK?
Bring zone-10+ plants indoors before the first frost — typically October across most UK regions. Place them in a frost-free greenhouse, conservatory or bright indoor space; reduce watering; keep away from cold draughts. For borderline zone-9 (half-hardy) plants, heavy fleece or straw mulch over the root zone can provide several degrees of protection. The RHS recommends a minimum of 5°C (41°F) for most tender tropical houseplants.
What is the difference between frost-tender and half-hardy plants?
Frost-tender plants (USDA zone 10+, RHS H1a–H2) cannot tolerate any sustained freeze — they will be damaged or killed at or below 32°F (0°C). Half-hardy plants (USDA zone 9, RHS H3) can tolerate light frost down to roughly 23°F (−5°C) but are killed by sustained hard freezes. In the Growli 2026 dataset, 36.8% of zone-tagged species are frost-tender and a further 17.6% are half-hardy — together 54.4% cannot safely overwinter outdoors in most of the UK or northern US.
Does RHS hardiness correspond to USDA zones for houseplants?
Broadly yes. USDA zone 10+ aligns with RHS H1a–H2 (tender, 'will not survive being frozen'). USDA zone 9 aligns with RHS H3 (half-hardy, tolerates light frost but not sustained freezing). USDA zone 8 and colder aligns with RHS H4–H7 (frost-hardy to fully hardy in most UK conditions). The systems were designed independently and the mapping is approximate.
What methodology does Growli use for hardiness zone data?
Each of the 5,561 species in Growli's catalogue carries a USDA hardiness zone rating drawn from the USDA Plant Hardiness Zone Map and horticultural reference databases. 5,472 of 5,561 species (98.4%) have a zone value; the 89 remaining are untagged and excluded from all percentages. 'Frost-tender' is defined strictly as minimum zone 10a or higher. USDA zones describe average annual extreme minimum temperatures for a location, not a per-winter guarantee — actual plant performance varies with microclimate, soil drainage, wind exposure and plant establishment.
Cite this study
Growli (2026). The Frost-Tender Houseplant Report 2026. getgrowli.app. Data licensed CC-BY 4.0 — free to quote, embed or chart with attribution to getgrowli.app.
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