One of the most common questions that new plant growers have regarding houseplants is how much and how often a plant should be watered. Although most plant varieties have different needs, in the end, it all comes to water drainage. Watering is intrinsically related to the drainage in a pot or the soil.
When gardeners talk about drainage, they refer to the capacity of the soil or the pot to let the excess water drain out after watering a plant. Once the soil gets saturated with water, any excess needs to drain out of the pot and off the soil for a plant to stay healthy. When there is an excess of moisture in the soil or the pot, the roots suffocate and eventually rot. Therefore, the plant’s health starts declining until it dies.
Watering plants in pots with water drainage
The best way to water plants in pots that have water drainage is to water the soil thoroughly, always making sure that the excess water drains out of the pot through the drainage holes below. Then, not water again until the soil feels dry to the touch, at least two or three inches deep into the soil. If the pot comes with a drip tray below, it helps to discard the water sitting in the tray to avoid root rot.
Watering plants in pots without drainage
So, what happens if a pot does not have drainage holes? Well, it may sound contradictory, but drainage isn’t always necessary, although it makes caring for our plants easier.
Drainage holes allow excess water to escape. If you add too much water at one time, it seeps out the drainage holes, and you can empty out the drip tray, so the plant doesn't drown. But if you're careful and don't get into a situation where you're not adding too much water at any one time, then the holes aren't necessary.
The best way to water a plant in a pot without drainage is to water it just enough to get the soil moist. The amount of water poured into the soil can’t be excessive. The right amount will depend on the size of the pot and the type of plant. For example, some succulents and cactus plants have a very shallow root system, so they take the water from the first layers of the soil. That means that there is no need to water the soil lower than its upper half.
Adding rocks below the soil for drainage
Adding rocks below the soil inside a pot is a bit of an urban myth. Although it sounds logical that the rocks should help the excess water to drain down, the combination of rocks and soil can get the soil compacted and trap the water in the soil for longer than it should. The rocks can also end up clogging the holes or create air pockets that can provide a perfect habitat for fungus and other bacteria.
Adding rocks will also reduce the amount of growing medium available to the plant’s roots to grow, thereby decreasing the plant’s potential maximum growth size.