No matter what type of plants you are growing, using containers with drainage holes is essential to their health.
A lack of drainage is one of the most common culprits in cases of unhealthy and dying plants.
Let us look into the reasons why indoor plants need drainage
Why do indoor plants need drainage?
Barring few aquatic plants, roots of plants don’t like to sit in water. They need to exchange oxygen and carbon dioxide with the air. Oxygen is used by the roots of the plant to stay healthy and to do their job of gathering water and nutrients for the plant.
Good soil drainage allows air into the soil for the roots to use. Excess water closes off air pockets in the soil.
This is exactly what happens when there are no draining holes. Such plants tend to become overwatered. The inner layer becomes very wet even if the outer layer of soil appears dry.
Waterlogged soil can lead to root rot which can eventually kill your plant. Root rot is an irreversible condition for the plant.
Signs of root rot are wilted and yellow leaves and the roots will be black or brown and slimy or mushy in nature. In other words, letting the plant soak in water for a long time will lead to their untimely demise.
Waterlogging can also occur if we let the water sit in the plant tray underneath. What happens is that water gets wicked back into the plant-soil making it soggy and wet and difficult for the roots to breathe.
Make sure to dump the water from the tray underneath the plant.
In the case of aquatic plants like water lilies and water hyacinths, they have developed ways to get air to their roots when the water has filled up all the air spaces in the soil.
They grow in water with the help of water movement which creates air bubbles. These air bubbles are used up by the plants.
Another major reason why drainage is important for plants is that they help in the flushing of salts from the soil. As you might be aware, tap water and fertilizers contain salt which gradually builds up in the soil.
This build-up of salts can harm the plants. When there is good drainage and we water thoroughly, water along with these salts flows out from the drainage holes in the bottom of the container and is flushed out.
With the absence of drainage holes, salts keep building up creating an unhealthy environment for the plants. Signs of salt buildup and improper drainage are that leaves turn brown on tips and edges and a whitish crust of salt on the soil surface.
What to do in case the pot does not have drainage holes?
In such cases, it is better to make one using a drilling machine. If that is not possible, use a double pot system and use the pot with no holes as a decorative pot.
For a double pot system, take a smaller porous pot with good drainage holes and place your plant in it. Next, place this small pot in a larger no drainage hole decorative pot.
Every time you want to water, remove the smaller container and water it in the sink. When it is finished draining, replace it in the decorative pot.
Sometimes a plant is already planted in a pot with no drainage at all. The best option for this plant is to take it to the sink, water it, then after a few minutes turn it on its side for a minute or two to let the excess water drain out.
If the plant is large, put some gravel or pebbles in the bottom of the decorative pot and place the functional pot with a plant and drainage holes on top of it.
This way gravel functions by keeping the plant’s roots away from sitting water. This method is a form of pebble humidity tray and a boon for humidity loving plants.
Double potting techniques may also be used to combine plants with different environmental requirements; to minimize extreme soil temperature fluctuations; to keep beautiful but invasive plants from spreading.
Beware of permanently attached plant trays or saucers in which emptying the overflow is difficult or impossible. Go for detachable water trays or saucers so that the plant-soil dries up a bit.
A word of caution here. Never place your plant without proper drainage outdoors in places where rain can fall on it. This is because you will not be able to regulate the amount of water your plant receives and can kill the plant with waterlogging and root rot.
Placing a gravel layer just beneath the soil layer in a pot to improve drainage is a myth. Instead of extra water draining immediately to the gravel, the water gathers into the soil just above the gravel.
The water keeps gathering until no air space is left. Once all the available soil air space fills up, excess water drains into the gravel below. So the gravel layer does little to keep the soil above it from getting saturated by overwatering.
However damp gravel placed in a saucer or a plant tray underneath the pot helps to increase the humidity in the immediate area of the plants as the water evaporates from the gravel surfaces.
How to Improve Drainage – Some Tips
One of the methods to improve drainage is to use a porous pot like a clay pot or a terracotta pot. A porous pot allows water to escape through evaporation. Use a deep pot rather than a shallow and small pot. A deep pot helps to increase porosity thereby improving drainage.
Using a good porous draining soil. Add compost for good air pockets and to improve the well-draining capacity of the soil. It opens up the porous structure allowing water to drain through and also acts as a sponge, holding required water in the soil where the plants can reach it.
Add coco coir or sand to allow for pore spaces to open up. Pore space is an area between one soil particle to the next and is often occupied by air.
Some of the good potting mix components are vermiculite, pine bark, perlite, sand, zeolite, soil, animal manure, wood chips, sawdust, etc.
From them, you can also make soilless mixes in an appropriate ratio. Certain gardeners recommend using activated charcoal. According to them, it is a highly porous material and effectively absorbs excess water. It also deters insects, molds, and eliminates odors.
Another way to improve drainage is to use self-watering pots. They effectively draw water from a bottom reservoir into the soil without causing the soil to become too wet.
Water is drawn up into the soil by capillary action or wicking. This is done with the help of small soil columns, rope wicks, or use of moisture sensors. Self-watering containers are especially useful for people who do not have time to check watering needs daily.
Drainage is a natural process by which water moves across, through, and out of the soil/ potting mix as a result of the force of gravity. So it’s a definitive yes to whether the plants need drainage and you must have well-draining soil and some good draining holes to allow excess water to exit.
These rules, however, don’t hold good for aquatic plants, shoreline plants who like constantly moist soil or those growing in shallow ponds like water lilies, pickerel rush, chameleon, etc.
Apart from them, almost all container plant roots require proper ventilation.
Regarding how many drainage holes, three to four (1/4th inch holes) are usually sufficient to drill in plastic, ceramic, metal, or resin planters.
Holes larger than 1/4th inch in diameter can allow some soil to escape along with water. Cover the holes with some chip of broken pottery or keep a stone over the hole on the inside of the pot below the soil to prevent the escape of soil from the drainage holes.
In case you do not have a drill, use a hot nail or a soldering iron with a sharp tip that can punch some holes. I have personally made holes in a plastic container by melting a certain point with the help of a lighted matchstick. How cool is that? Be creative and try the options available and easy for you.
Summing up, plant roots cannot survive without two elements: air and water. In nature, these two elements can rarely coexist together. If one is in abundance, the other one becomes limited.
Both of these are critical to plant root development. Without adequate water being absorbed by the plant’s roots, the transport of nutrients stops inside the plant.
On the other hand, they need oxygen as well or else the roots will suffocate causing the plant to die prematurely.
Too much air will mean inadequate water or moisture and too much water will inhibit air availability. This is where plants need good drainage. Good drainage will ensure that soil holds the water required and removes excess creating a balanced environment for the plant roots.
Good drainage for indoor plants will also increase the efficiency of phosphorus fertilizer, conserve nitrogen, control waterlogging, leaching, and remove salt deposits.
Choose your plant, your soil, and your pot accordingly. All the best!
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