Watering kills more houseplants than pests, light and cold put together. Not because it is difficult, but because the advice people are given is a number of days, and a number of days is the one thing that cannot be right.
Why schedules fail
The same plant in the same pot needs water at wildly different rates depending on the season, the light, the temperature, the pot material and how root-bound it is.
A Monstera by a bright window in July might want water twice a week. The same plant in the same spot in December might want it once a fortnight. Watering it weekly all year means drowning it for half the year and starving it for the other half.
Use a schedule as a reminder to check, never as a reminder to water.
How to tell when a plant needs water
The finger test
Push a finger 3-5cm (1-2 inches) into the soil. If it comes out with soil clinging to it, wait. If it comes out clean and dry, water.
This is unglamorous and it is the most reliable method there is.
Weight
Lift the pot after watering, then lift it again a few days later. A dry pot is dramatically lighter. Once you know the difference for a given plant you can judge it in a second.
The plant itself
Some plants tell you clearly. Pothos and Peace Lilies go limp and recover within hours. Fittonia collapses flat. These are useful signals, but relying on them means the plant is already stressed each time.
Moisture meters
They measure conductivity rather than water, so mineral content and compaction throw them off. Useful as a rough check on a large pot you cannot get a finger into, unreliable as a sole method.
How much to give
Water thoroughly until it runs freely from the drainage holes, then let it drain completely and empty the saucer.
Small frequent sips are worse than they sound. They wet only the top of the soil, so the deeper roots stay dry and the shallow ones do all the work. They also leave fertiliser salts behind, which build up and burn the roots.
Never leave a pot standing in water
This is the single most common way a houseplant dies. Roots need air as well as water, and soil that never drains suffocates them.
Overwatering is not about volume
Overwatering means watering too often, not too much at once. A plant given a thorough soak every three weeks is not overwatered. A plant given a small drink every three days is, even though it receives less water overall.
The distinction matters because people respond to a sick plant by watering less at a time rather than less often, which makes it worse.
Telling the two apart
Overwatered and underwatered plants both droop, which is why so many plants get watered to death. Check the soil before doing anything.
| Symptom | Overwatered | Underwatered |
|---|---|---|
| Soil | Wet, sometimes smells sour | Bone dry, may be shrunk from the pot |
| Leaves | Yellow, soft, limp | Crisp, browning at the edges |
| Stems | Soft or mushy near the soil | Firm |
| Recovery | Slow or none | Within hours of watering |
Water quality
Most plants do not care. A handful care a great deal.
Calathea, Maranta, Spider Plants, Dracaena and most ferns are sensitive to fluoride and chlorine in tap water, and show it as brown, crisp leaf tips. Filtered water, distilled water or rainwater solves it. Leaving tap water to stand overnight lets chlorine off-gas, but does nothing about fluoride.
The seasonal shift
Growth slows or stops in autumn and winter for most houseplants, and water use drops with it. Keep watering at summer frequency and you will rot the roots just as the plant is least able to recover.
As a rough guide, halve the frequency from late autumn until new growth appears in spring.
Bottom watering
Standing the pot in a tray of water and letting it soak up from below works well, and it encourages roots to grow downward.
It has one drawback: it never flushes the soil, so fertiliser salts accumulate. Water from the top every third or fourth time to wash them through.