Shedding some light on "overwatering"

Shedding some light on "overwatering" The term "overwatering" is thrown around so much but it has only served to strike fear in the usually satisfying task of watering your house plants. Fear breeds insecurity but knowledge promotes confidence - let me encourage you to gain confidence in watering your house plants... Understand the enemy: I wrote this article to help you understand that several factors need to come together before a plant will die of root rot. It's more than simply watering too often or too much. The other factors protecting plants are light intensity and soil structure. To summarize: a plant that is not growing (inadequate light), sitting in moist soil with little airflow is at high risk of root rot.

How plants work: plants sustain themselves by producing sugar from combining water and carbon dioxide. The rate at which this reaction occurs depends on the intensity of light received. Direct sun is not always required for photosynthesis. Many tropical foliage plants only require what's called "bright indirect light" - ***this is the light that comes from an open sky during the day*** - therefore, as long as these "low light" plants can see the sky (and not necessarily the sun), they will photosynthesize. The farther they are placed from the view of the sky, the less they will photosynthesize. Soil moisture usage: when your plants get enough light, they will grow. As they grow, they will draw up moisture from the soil. As the daily average light intensity decreases, so does the rate of photosynthesis, and so does the rate of moisture decrease from the soil. Thus, the less light you give a plant, the less soil moisture decreases. It is the prolonged moist soil that promotes the conditions for root rot.

'Okay' solution: avoid bringing the soil to maximum saturation when a plant is barely photosynthesizing. But you're basically starving the plant by not giving it the opportunity to photosynthesize - a kind of low light life support. No plant will survive for long if it isn't growing. Another 'okay' solution: you could repot the plant with soil that has a higher drainage/retention ratio. For example, instead of using 1 part perlite to 4-5 parts peat moss, you could increase that to 1 part perlite to 3-4 parts peat. This is an okay approach because the soil will not hold enough water to create the conditions for rot but the plant is still going to starve for light. 'Best' solution: move the plant to a place where it can see as much of the sky as possible but be shielded from the sun, if necessary (like for tropical foliage plants). In the right light, you can safely bring the soil to maximum saturation - a properly lit plant will rarely die of root rot because the soil moisture is being used up before anaerobic bacteria have a chance to multiply.

'In-between' solution: if you really must keep a plant in a less than optimal position (light-wise), you can manipulate soil structure to prevent pockets where moist soil can become stale. Do this by soil aeration - gently poking holes into the soil with a chopstick. This happens in nature by the action of worms and insects - your indoor plants miss them! In my mind, overwatering isn't the true #1 killer of house plants, it is under-lighting. If a plant is not getting enough light, it will eventually die whether you water it or not. Light is the driver of plant life. Further rambling (skip if you want): Here's an analogy with human life. Would you rather: A) Be forced to walk 8,000 steps per day (average for healthy activity) but be allowed to eat as much as you want. B) Be forced to eat only 1,200 calories per day (minimum to survive) but be allowed to lie in bed all day to conserve energy. I hope your answer is most obviously A). Unfortunately for house plants, we tend to force them into situation B) when we don't understand their light requirements. To make matters worse, we also expect them to look perfect and/or grow while they are starving. If you want to enjoy thriving house plants, you must start with the right light.