The RHS gardenia growing guide says to keep gardenia compost constantly moist but not saturated in spring and summer, to water less in winter without letting it dry out, and to use rainwater where possible, especially in hard water areas. It also says gardenias need high humidity, to stand pots on damp gravel, and to avoid misting while plants are in flower. The RHS does not give a pH or hardness figure.
Water type
The RHS says rainwater is preferable, especially in hard water areas. It does not explain why, and gives no mineral figures. Gardenias need acid conditions (see Soil pH for Gardenia), which is the likely reason hard water is a concern, but that link is not spelled out on the page.
How much and how often
| Season | What the RHS says |
|---|---|
| Spring and summer | Keep compost constantly moist, but not saturated |
| Winter | Water less, without letting it dry out |
| Humidity | High; damp gravel under the pot; no misting in flower |
Watering mistakes and bud drop
The RHS says bud drop is usually caused by extreme or fluctuating temperatures or by irregular watering. Clemson lists low humidity, over- or under-watering, insufficient light and high temperatures. See Gardenia Bud Drop and Gardenia Humidity Indoors.
What the sources do not cover
They give no watering interval in days, no volume per pot, and no test for tap water. The advice is a pattern: steady moisture, less in winter, rainwater when possible.
Frequently asked questions
Should I use rainwater on gardenias?
The RHS says where possible, especially in hard water areas.
Should I mist a gardenia?
The RHS says to avoid misting while plants are in flower, and to use damp gravel under the pot for humidity.
How wet should the compost be?
Constantly moist, but not saturated, in spring and summer, according to the RHS.
Sources read for this page
Last reviewed 15 October 2026. Written by Md. Firozur Rahman. This page gives general guidance and cannot diagnose a plant from a description; see the Disclaimer. Back to the Gardenia hub.
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