How we read sources
Everything in the care table is what somebody published. The simulator is a drawing, and it needs boundaries on four axes where the sources mostly give words. This page shows every figure it uses and where each came from, so the drawing can be checked rather than trusted.
Three kinds of boundary
Every slider is in real units: degrees, foot-candles, percent relative humidity, and a soil-moisture scale from bone dry to standing water. Each boundary on it is one of three things, and the slider says which.
- This plant’s own figure. The RHS hardiness rating gives a cold floor in degrees for every plant here, and Clemson gives a light band in foot-candles for some.
- A general figure for its kind of plant, from a named extension service, used where no source publishes one for the species: where tropical foliage is chilled, what temperature indoor plants grow best in, what humidity houseplants prefer. These are listed below, each with the words it was read from.
- This site’s reading of a source’s wording, where the source gives words and no figure: RHS sitings such as “Partial shade”, and RHS soil descriptions such as “Moist but well-drained”. The table further down is that reading.
The general figures
Which of these apply depends on the kind of plant, read from what the site already holds: a succulent form uses the cactus and succulent figures; a plant whose hardiness floor is above freezing uses the tropical foliage ones; a plant rated to take frost uses the cool-growing ones. Where a source prints Fahrenheit only, the slider shows the same temperature in Celsius alongside it, rounded to a degree.
| Used for | Source | What the page says (quoted, or restated where its text is not licensed) | Read |
|---|---|---|---|
| Freezing, tender plants | UF/IFAS Extension | “A chilling temperature can be any temperature that is cold enough to cause injury but not cold enough to freeze the plant, usually ranging from just above 32°F to 59°F.” | 2026-09-13 |
| Chilling, tropical foliage | UF/IFAS Extension | “The majority of the foliage plants grown in Florida are subtropical and tropical in origin and are susceptible to damage at temperatures below about 50°F [10°C]” | 2026-09-13 |
| Grows best, foliage plants | University of Maryland Extension | “In general, foliage indoor plants grow best between 70° and 80°F during the day and from 60° to 68°F at night” | 2026-09-13 |
| Heat stress, indoor plants | University of Georgia Extension | “interior plants can tolerate and grow well in the 58 °F–86 °F range because most indoor plants originate from tropical and subtropical areas” | 2026-09-13 |
| Cool rest, cacti and succulents | RHS | In winter, keep nights cool, around 8-10°C (46-50°F), and water little or not at all. | 2026-09-13 |
| Grows best, cacti | Clemson Extension | “Cacti prefer temperatures from 65 to 85 F during the growing season.” | 2026-09-13 |
| Cool-growing plants | NC State Extension | Plants that like it cool do best with days at 50°F – 60°F and nights at 45°F – 55°F. | 2026-09-13 |
| Warm-growing plants | NC State Extension | Plants that like warmth do best with days at 70°F – 80°F and nights at 64°F – 70°F. | 2026-09-13 |
| Light bands | Clemson Extension | “Low (minimum 100 ft-c, 75 to 200 preferred for good growth) Medium (minimum 100 to 150 ft-c, 200 to 500 preferred) High (minimum 150 to 1000 ft-c, 500 to 1000 preferred) Very high (minimum 1000 ft-c, 1000+ preferred)” | 2026-09-13 |
| Too dark to sustain a plant | Mississippi State University Extension | “an intensity of less than 50 foot-candles will not sustain plant life for very long” | 2026-09-13 |
| Full sun outdoors | Clemson Extension | “outdoor light intensity on a clear sunny day may exceed 10,000 ft-c” | 2026-09-13 |
| Shade outdoors | University of Georgia Extension | “Outdoors, the light levels on a bright day range from 10,000 ft-c in an open sunny area to 250 ft-c or less in the shade” | 2026-09-13 |
| Humidity preferred | University of Nebraska–Lincoln Extension | “Humidity levels between 40 and 60 percent are preferred.” | 2026-09-13 |
| Humidity injury | University of Nebraska–Lincoln Extension | “Most houseplants are injured when humidity is under 20 percent, with the exception of succulents.” | 2026-09-13 |
| Humidity, tropical origin | Mississippi State University Extension | “compared to the 70 to 90 percent humidity levels found in the native climates of most tropical plants” | 2026-09-13 |
| Humidity, cacti and succulents | University of Arizona Extension | “However, cactus and other succulents are perfectly at home in a humidity range of 5–15%.” | 2026-09-13 |
| Damp and disease | NC State Extension | Botrytis blight is kept in check by avoiding what favours it: humidity of 85% or more combined with cool air at 60-70°F. | 2026-09-13 |
| Watering check | University of Arizona Extension | “When the top inch of the soil in containers up to 8–10 inches in diameter feels dry, the plant probably needs watering.” | 2026-09-13 |
| Roots and waterlogging | Clemson Extension | “Roots need both water and oxygen, and when surrounded by water, they cannot take up oxygen. These roots may rot and eventually the whole plant may die.” | 2026-09-13 |
Where the site draws a direction, not a figure
Two boundaries have no published figure behind them, and the slider says so where they appear. Light more than about four times a plant’s upper figure is drawn as bleaching, and ten times as scorch: light acts in ratios, and no source read prints where scorch starts for these plants. And the damp end of the humidity slider for a succulent starts at 60%: the sources say succulents manage in dry air, not where damp begins to harm them.
Reading RHS sitings as light
RHS describes where to site a plant outdoors; Clemson measures what reaches the leaf indoors. Where Clemson rates a plant, its printed foot-candles are used. Where only RHS does, “Full shade” is read as up to 250 foot-candles, “Partial shade” as 250 to 2,000, and “Full sun” as 1,000 to 10,000, from the outdoor figures in the table above. That reading is this site’s.
Two vocabularies, one axis
The care table and the soil-moisture slider still use the table below, which puts each source’s wording on a 0 to 100 position. Where two sources disagree, the plant’s page says so and names both; this table only makes the disagreement visible.
| Source | Attribute | Wording | Band |
|---|---|---|---|
| RHS | light | Full shade | 0–30 |
| RHS | light | Partial shade | 25–60 |
| RHS | light | Full sun | 65–100 |
| Clemson Extension | light | Low light | 10–40 |
| Clemson Extension | light | Medium light | 35–65 |
| Clemson Extension | light | High light | 60–100 |
| NC State Extension | light | Full Sun | 65–100 |
| NC State Extension | light | Partial Shade | 25–60 |
| NC State Extension | light | Dappled Sunlight | 25–55 |
| NC State Extension | light | Deep shade | 0–30 |
| RHS | water | Well-drained | 20–50 |
| RHS | water | Moist but well-drained | 40–70 |
| RHS | water | Poorly drained | 60–90 |
| NC State Extension | water | Good Drainage | 20–50 |
| NC State Extension | water | Moist | 40–70 |
| NC State Extension | water | Occasionally Dry | 15–45 |
| NC State Extension | water | Occasionally Wet | 55–85 |
Where a source names more than one siting
A claim reading “Full sun, Partial shade” is read as the union of both, because that is what the source is saying: either will do.
When two sources are treated as agreeing
Where their bands overlap by at least ten points of the axis, the overlap is used, since it is the part both of them vouch for. Where they overlap by less, they are treated as describing different conditions and the wider span is used instead. The fiddle-leaf fig is the case that forced this: one source puts it in full sun and the other in a middling band, and those meet at a single point, which produced a comfortable range one point wide that no reader could satisfy.
Temperature has a top now, and it is general
No source read for this site publishes an upper temperature for any plant it covers. The warm end of the slider uses general figures for indoor plants instead, marked as general, and says so. Before those were found the slider ran to the top of its axis with nothing drawn, which told readers nothing.
What this does not cover
These are readings of published words and general figures for kinds of plant, and either can be wrong for a particular plant. None of it says how much light actually reaches a particular windowsill, or how long a cold night lasted, which are the numbers that would settle most of it and which nobody can publish for you.