Quick Answer: Orchids need warmer, more humid conditions than most greenhouse crops, but the exact numbers depend on which of the American Orchid Society’s three temperature groups they fall into: warm growers want 80–90°F days and 65–70°F nights, intermediate growers (the largest group) want 70–80°F days and 55–65°F nights, and cool growers want 60–70°F days and 50–55°F nights. Almost all orchids share two other needs regardless of group: 60–80% relative humidity and a 10–15°F day/night temperature drop to trigger blooming. Get the temperature group right and pair it with heavier shade cloth than a vegetable house needs, and most of our greenhouse kit picks can support a thriving orchid collection.
If you’ve read our guides on greenhouse tomatoes, peppers, cucumbers, or succulents, orchids add a wrinkle none of those crops have: there isn’t one orchid target temperature, there are three. Cattleya, Phalaenopsis, Cymbidium, and Dendrobium don’t all want the same greenhouse conditions, and picking the wrong group for your species is the most common reason an orchid survives in a greenhouse without ever blooming.
Greenhouse orchids by the numbers:
- 65–90°F daytime range — the full span across all three American Orchid Society temperature groups, from 60–70°F for cool growers up to 80–90°F for warm growers. Knowing which group your orchids belong to matters more than any single “ideal” number.
- 10–15°F — the day/night temperature drop most consistently linked to orchid blooming across all three groups; without it, plant respiration and metabolism suffer even when daytime conditions look correct.
- 60–80% relative humidity — the range most orchids do best in, well above the 40–60% University of New Hampshire Extension recommends for common houseplants, and closer to the 65–90% our tomato and pepper guides call for.
- 60–70% shade cloth — the density that works best for most orchids, heavier than the 30–50% default for vegetables in our shade cloth guide.
The three temperature groups
Unlike the single-target crops in the rest of this series, orchids split into three distinct temperature preferences based on their native elevation and climate:
| Group | Daytime | Nighttime | Common genera |
|---|---|---|---|
| Cool | 60–70°F | 50–55°F | Cymbidium, Odontoglossum, Miltonia |
| Intermediate | 70–80°F | 55–65°F | Cattleya, Phalaenopsis, most Dendrobium |
| Warm | 80–90°F | 65–70°F | Vanda, Phalaenopsis (some), tropical species |
Intermediate growers make up the largest share of orchids sold at retail, which is why most hobby greenhouses default to intermediate settings and treat cool- and warm-group species as the exception rather than the rule. If your collection mixes all three groups, running the house for the intermediate range and giving cool- or warm-group orchids their own shaded or heated microclimate on a separate bench works better than trying to satisfy all three with one thermostat setting.
Digital Greenhouse Thermometer & Hygrometer
- Confirms the day/night temperature drop is actually happening instead of assuming it from an average reading.
- Tracks humidity alongside temperature — orchids fail more often from missed humidity swings than missed temperature swings.
- Worth the upgrade over a basic dial thermometer for an orchid collection specifically, where one missed cold night can be expensive.
Building out a dedicated orchid bench with humidity trays, a hygrometer, and the right shade cloth is exactly the kind of recurring supply list Kindle Unlimited pairs well with — load an orchid-care field guide while you wait on gear to arrive. Sponsored link — we may earn a fee if you sign up. No extra cost to you.
Getting humidity right
Most orchids want 60–80% relative humidity, well above what common houseplants tolerate and closer to the high end of what our tomato and cucumber guides call for. In winter especially, greenhouses tend to run drier as heating systems pull moisture out of the air, so a hygrometer reading is worth checking daily rather than assumed. Humidity trays — a layer of pebbles kept wet under the pots — raise local humidity around the plants without soaking the roots directly, and a greenhouse humidifier with a hygrometer-linked auto-shutoff prevents the sustained high readings that invite fungal disease in a shared structure.
Light and shade cloth
Orchids need 10–16 hours of light a day, but not all orchids want the same intensity. Soft, thin-leaved types like Phalaenopsis want less direct light and do well with heavier shading, while hard, leathery-leaved types like Cattleya and Vanda tolerate — and often prefer — being hung close to the glazing. Across the group, 60–70% shade cloth is the common recommendation, noticeably heavier than the 30–50% that works for most greenhouse vegetables. Our shade cloth guide covers the full range if you’re running a mixed structure that needs both densities on different sides of the house.
The night-drop that triggers blooming
A 10–15°F drop between day and night temperatures is one of the most consistent blooming triggers across all three orchid temperature groups. A greenhouse that holds a flat temperature around the clock — common in smaller structures with a single thermostat-controlled heater — will often keep orchids alive and green without ever coaxing them into flower. If your structure runs unusually stable overnight, cracking a vent slightly before sunset or scaling back supplemental heat a few hours earlier can reintroduce that drop without risking cold damage.
Ventilation and airflow
Automatic humidifying equipment works best paired with steady air movement, not against it. Side and roof vents — automatic or manual — combined with a circulating fan keep moisture-laden air moving through the structure instead of settling as standing humidity on leaves, which is one of the more common paths to fungal problems in a high-humidity orchid house. A greenhouse fan running continuously at low speed, alongside vents sized to your structure using the guidance in our greenhouse ventilation guide, does most of the work here.
Growing orchids alongside other crops
| Factor | Tomatoes / Peppers / Cucumbers | Orchids (intermediate) |
|---|---|---|
| Daytime temperature | 70–80°F | 70–80°F |
| Nighttime temperature | Modest drop | 55–65°F, 10–15°F drop required for blooms |
| Humidity target | 65–90% | 60–80% |
| Shade cloth | 30–50% | 60–70% |
| Biggest failure mode | Blossom drop from heat/humidity swings | No blooms from a missing night-temperature drop |
The temperature overlap with intermediate-group orchids is closer to fruiting vegetables than you’d expect — the two things vegetables don’t need that orchids do are heavier shade and a deliberate nighttime temperature drop. A shared structure works fine if you zone for those two differences rather than assuming one setting suits both.
How to choose
- Identify your temperature group first. Cool, intermediate, and warm growers have genuinely different needs — a Cymbidium and a Vanda in the same unzoned house means one of them is unhappy.
- Don’t skip the night-temperature drop. A flat, stable temperature is often why an otherwise healthy orchid never blooms.
- Run heavier shade than your vegetables need — 60–70% for orchids versus 30–50% for most fruiting crops.
- Track humidity, not just temperature. A combined hygrometer/thermometer catches the dry swings a heating system causes in winter that a temperature-only check misses.
- Zone a mixed greenhouse rather than compromising the whole structure to split the difference between orchids and vegetables.
The bottom line
Orchids are less forgiving of a one-size-fits-all greenhouse setting than most of the crops in this series, because “orchid” really means three different temperature preferences depending on genus. Nail down your group, hold 60–80% humidity, run heavier shade cloth than your vegetables need, and don’t skip the nightly temperature drop — get those four right and a greenhouse orchid collection blooms reliably instead of just staying alive.
Still shopping for the structure itself? Our best greenhouse kit roundup and best mini greenhouse picks both work well for a dedicated orchid bench, and our greenhouse thermometer guide covers the monitoring gear that matters most for a temperature-sensitive orchid setup.