To keep plants alive, you need a number of things:
- Nutrients
- Light
- Water
Of these, the first two are usually handled by nutrient-rich soil and putting the plant in a well-lit place, respectively. The main issue with keeping plants alive after satisfying those two points is usually the third point, as this has to be handled on a daily basis.
Here, it's not just a simple matter of keeping the water topped up, but instead of staying within the range where the soil has enough but not too much water. The presence of too much water in the soil affects how much oxygen the plant can absorb via its roots. As a result, with too much water in the soil, the plant will wither and die.
On the other hand, too little water means that the plant cannot take up enough water to compensate for the water that is being evaporated through its leaves, nor can it get the nutrients into its roots. In this case, the plant will also wither and die.
When manually watering plants, we tend to use rough estimates...
