Rubiaceae
Coffea
133 species, of which two carry the entire world coffee trade. The one grown here, Coffea arabica, is an understorey tree of Ethiopian montane forest — which is the key to everything about keeping it, because almost all the advice in circulation is written for an irrigated plantation in full sun. It is also, despite the drink being everywhere, Endangered in the wild.
Native to Tropical Africa, Madagascar, the Mascarenes and Asia
How Coffea generally wants to be treated
Species pages start from this and record only where they differ.
- Light
- Dappled shade to partial shade — two to six hours of direct sun. This is a forest understorey plant growing wild between about 950 and 1,950 m, and full sun is a field-production choice rather than what the plant is built for. No source at this level publishes a lux figure.
- Water
- Consistently moist but never soggy, in a mix that drains well. But see the dormancy field: watering it evenly all year is one of the three reasons a houseplant coffee never flowers.
- Humidity
- High. NC State names it as one of three indoor requirements alongside bright light and a free-draining mix, and nobody publishes a percentage.
- Temperature
- Kew gives the optimum mean as 64-73 °F (18-23 °C). Indoors, 70-80 °F (21-27 °C) by day and 60-65 °F (16-18 °C) at night. Leaf drop starts below 55 °F (13 °C) — well above freezing, and the usual reason a coffee plant sulks after a cold snap indoors.
- Substrate
- A free-draining potting mix, slightly acid. Nothing exotic; drainage matters more than the recipe.
- Fertilizer
- No published rate exists for an indoor coffee plant at any level of source I could reach, so this record does not invent one. A balanced feed at half strength through the growing season is the conventional approach.
- Propagation
- Seed, sown fresh. Coffee is the textbook example of intermediate storage behaviour: the seed does not survive drying, so a dried or roasted bean is dead and will never germinate. Cuttings are used commercially, with a caution this record cannot source properly — see the species page.
- Dormancy
- No true dormancy, but flowering has real requirements that a comfortable room defeats. Bud initiation fails above a 13-hour photoperiod and above 82 °F (28 °C), and floral bud dormancy is broken by a dry period followed by re-wetting. A plant kept warm, evenly lit and evenly watered is being told, three separate ways, not to flower.
- Common problems
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- Leaf drop after a cold night — the threshold is 55 °F (13 °C), not freezing
- Scorched or bleached leaves in direct sun; this is an understorey plant
- It never flowers, which is usually correct behaviour rather than a fault — see dormancy
- Stripping the side branches for a tidy single stem removes the wood that flowers, since the flowers are borne on lateral branches
- Spider mites and mealybugs in dry indoor air
- Every part contains caffeine, and it is genuinely dangerous to a dog or cat rather than merely irritant
In the collection
- Coffee plant Coffea arabica L.