The primary points for understanding how to water plants outlined in part I (The previous blog) were 1. determining when your plant requires watering by testing the dryness of the soil, and 2. Observing how the amount of light affects how fast your plant dries out.
Another important factor is: The size of the nursery container relative to the size of the plant. By nursery container, we mean the plastic container with drainage holes enclosing the rootball of your plant. Indoors especially, it is best to place this container inside the decorative container. This way you have water drainage, but the outer container will keep it from leaking on to your floor. This also makes it easier if you ever need to remove the plant! Naturally if you don’t have good drainage, it is more likely that your plant will become overwatered eventually.
It is usually best that indoor plants remain in their nursery container as long as possible. Unlike outdoor plants and trees, they rarely receive very bright light for extended periods. Therefore once you have watered the plant, the goal is for the soil to drain and dry out within a week if possible.
With the exception of very small plants (6″ pot or smaller), the nursery container your plant came in will stay moist enough for atleast 7 days. The larger your nursery container (or growpot) is, relative to the size of the plant, the longer the roots will stay wet, so repotting to a larger size is not necessary until your plant has grown quite a bit. When a plant or tree grows, and its foliage becomes taller and bushier, its roots are growing in all directions and starting to fill up the pot. However indoor plants usually grow very slowly unless they receive consistently bright light.
The point to remember is that noticing how full and bushy the foliage is, and noticing the size of the nursery pot, can help you to predict how fast the plant will use its water, and how much water it will need once it is dry. The more you observe plants the better understanding you will have of the size of the pot relative to the size of the plant. This is especially true in a plant store where the nursery pots are always plainly visible.
Noticing the brightness of the environment of a particular plant will also help you predict how fast it will use its water. This is common sense really, but you also need to observe it at different times during the day to have an idea of the duration of the light and average brightness of that area. Temperature, which also affects the rate at which a plant dries out, generally increases along with brightness of light, but indoor air conditioning or heating can affect plants independent of light intensity.
Please let me know if this was helpful, and feel free to respond with any questions!