Good soil drainage. This topic is often mentioned but never discussed at length. People advise you to ensure your plants have proper drainage, or you may have read it in blogs, but no one tells you how to do that. You may have seen expensive potting soil advertised to have excellent drainage, but can you make it home? The answer is yes, and we’re going to tell you how.
What is Good Drainage?
We all know drainage means removing water from an object or place that holds water in excess. You may picture your shower drain or the drain in the kitchen sink. However, what do we mean by good drainage when discussing house plant soil?
Good drainage creates the perfect balance between water and oxygen surrounding plant roots. Soil with good drainage doesn’t drain too slowly, causing water to pool or puddle around the roots and depriving them of air.
When there is too much water in the pot, it pushes out all the oxygen from the soil. Nor does it drain too fast, causing the roots to be exposed to too much oxygen and not giving them time to absorb enough water.
Some plants like moist soil. For such plants, the soil mix is crafted to hold more water while still draining enough not to keep the roots too soggy.
Other plants, like succulents, like quick-drying soil that drains very fast. So, good drainage can be slightly different for different kinds of plants.
To summarize, good drainage means soil that doesn’t hold onto water for too long or lose all the water too fast.
Outdoor and Container Gardening
We do not have to worry about drainage when we plant things in the soil outside. That is because when we water our plants outside or if it rains, there are several ways the water is naturally removed from around the roots.
First of all, competing plants partake in the water alongside the plant. Their roots may touch or even overlap in places. While in containers, we usually have one plant per pot.
These plants try to complete their water needs even if that means reducing the water for other plants. When there is an ample amount of water in the soil, the competing plants help drain access water.
Deeper Soil and Larger Surface Area
Secondly, the soil outside runs deep down to the bedrock. There is plenty of room for the water to sink deeper and deeper into the ground. Also, there is a lot of area around the plant as well. At the same time, pots have a limited depth and space for the water to go.
Outside, the sun shines directly on the soil unless there is some shade. The sun can evaporate the water in the soil much faster than it does for plants inside. Even if a plant is in the shade outside, the soil outside the shade will lose water and pull the excess water.
The first thing we do to ensure proper drainage for our plants is to get planters with drainage holes. We know that some gorgeous decorative planters do not come with drainage holes. However, that’s all they are suitable for, decoration. Such planters do not even provide rudimentary houseplant drainage.
If you have fallen in love with a planter that lacks drainage holes, we cannot stop you from getting it. Regardless, we can give you advice on how to make it work. There are two things you can do. You can bore out or drill drainage holes yourself.
However, some planters look like they might break, or you can’t find the right tools to make holes in them. In that case, you can take a plain terracotta plant pot with drainage holes and place that in the decorative pot over a layer of pebbles or granite.
The stones or granite ensure that the pot stays above the water that drains out of it. However, you must manually drain the decorative pot whenever the water level rises too high and starts to touch the terracotta pot.
Are Drainage Holes Enough?
In most cases, drainage holes are not enough. That is because nutrient-rich pot soil holds on to too much water. Drainage holes work using gravity. The water flows down through the soil and eventually seeps out of the holes from the Earth’s gravitational pull.
However, water has cohesion and adhesion properties that make it hold onto the tiny grains and particles of soil in the pot. The forces of these properties are more potent than gravity when there are tiny particles of soil mix.
That is because there are minimal gaps between these particles, and when the water fills these gaps, they push out all the oxygen and cling to the soil particles.
There is a straightforward solution to this problem. If we add some larger particles to the average soil mix, we increase the gaps in the soil. When the water starts to fill these larger gaps, gravity is stronger than the force of the water’s adhesion to the soil. There is also plenty of space for oxygen to hang out in the moist but not soggy soil around the roots.
Therefore drainage holes aren’t enough on their own. While they provide a place for the water to go, they cannot ensure the soil doesn’t hold onto the water too long.
Problems Caused by Poor Drainage
When plants do not have sufficient drainage, they suffer the same way as if they were being constantly overwatered. The roots start to die, and the plant becomes less robust until it too dies. Here are some issues caused by improper drainage:
- Houseplant leaves turning yellow
- Stunted or slow growth
- Wilting or bending stems
- Root rot
Make Well-drained Soil for Houseplants
Well-drained soil for house plants needs to have a balance of organic and inorganic substances. We need nutrient-rich materials and stuff to hold moisture in the soil. We need larger particles to ensure the drainage as well.
Requirements of Houseplant Soil
Plants need their soil to fulfill their four necessities:
Roots need oxygen since roots take part in respiration. That means they breathe in the oxygen and release carbon dioxide in its place.
Plants need water to survive. They need water for their structural integrity or turgidity, for photosynthesis, and to transport nutrients to different parts of the plant.
Plant roots dig into the soil and carry the weight of the entire plant. In nature, the roots can go deep and far enough or anchor themselves to rocks to hold the plant.
Soil is the source of potassium, nitrogen, sulfur, calcium, magnesium, and more essential nutrients plants need to grow and survive.
How To Make Well-Drained Soil For Houseplants
To make well-drained soil for houseplants that fulfills all its requirements, we need:
A source of nutrients, the primary substrate, something to hold moisture, and drainage material. You can add soil from your garden or nearby land for the primary substrate or buy some dirt from a nursery.
Here are some things you can add to make your soil nutrient rich:
- leaf mold
- aged manure
Some plants need slightly acidic soil, while others need neutral to slightly basic soil. You can use soil amendments to raise or lower the ph of the soil. To know the current ph of your soil mixture, you will have to test it.
You can use lime or baking soda to raise the soil’s pH. Conversely, you can add aluminum sulfate to lower the soil’s pH, making it more acidic.
For plants that enjoy moist soil, you can add coconut coir or clay soil to ensure your soil retains enough water. Balancing these moisture-retaining soil amendments with drainage amendments will ensure that the soil does not hold too much moisture. You should not use more than forty percent coconut coir or clay soil in your pot mixture.
There are also moisture retainers that have a larger particle size than coconut coir or clay soil, so they aerate the soil along with retaining moisture. These materials both help water drain while holding on to water. Some examples are perlite, vermiculite, and pumice stones.
Drainage Soil Amendments
Drainage amendments are the things that make sure that water drains out of the soil into the drainage holes fast enough. These have a much bigger particle size than other parts of the soil mixture.
You can make well-drained soil for houseplants by using up to thirty percent drainage material in your soil mix. Here are some good options.
Gravel is the aggregate of crushed or sounded rocks larger than sand. It is cheap and readily available, making it the first choice for many houseplant owners.
You can add sand into your basic soil mix if your soil is very rich in clay or compost. To create the perfect loamy soil, you must balance clay and sand. Some plants, especially succulents, prefer sandier soil.
LECA stands for lightweight expanding clay aggregate. These are balls made of clay that are baked in a kiln. They are porous and expand when they come in contact with water. You may think using clay to improve drainage is counterproductive as it holds onto water.
However, LECA is usually used on its own as the main substrate since it also holds nutrients. If used in the soil mix, it improves physical drainage because of its size while retaining both water and air in its crevices.
Perlite is another all-rounder soil amendment like LECA. It can hold water and air and improve drainage simultaneously. However, perlite doesn’t contain nutrients as LECA does. Using this is a great way to ensure that moisture slowly releases into the soil without puddling around the roots.
Vermiculite is an ore formed when phyllosilicates are heated at high temperatures. It is similar to perlite as it is highly porous and retains moisture well. However, perlite aerates the soil more. Vermiculite is only suitable for plants that love a lot of water or to fix very sandy soil.
Ideal Soil Mix Proportions
The ideal soil mixture for most plants has two parts. The main soil mix and the drainage amendments. To proportions for the basic soil mix are:
- Thiry percent nutrient-rich material like compost or manure
- thirty percent substrate
- thirty percent moisture retaining soil amendments
In a large container, combine the prepared soil mix and drainage material of your choice. Or seventy percent soil and thirty percent drainage material. This is a balanced ratio that guarantees that the water requirements of your plant it met without waterlogging the plant.
If we have a plant that needs dryer soil, we can add more drainage material than substrate to the soil mix. You can mix even fifty percent soil and fifty percent sand for succulents. They will handle it.
The takeaway is that good drainage means much more to the plant than water leaving the pot. We must find the perfect balance of water and air in the pot.
To create the optimum root environment, there must be ample air and nutrients and something for roots to hold on to. We can make well-drained soil for houseplants at home instead of spending huge amounts of money.
If you think about it, early houseplant owners most likely used the soil they found outside for free. We suppose you can make your perfect plant mix in the spirit of doing things ourselves and being less reliant and more sustainable. Once you have mastered basic plant soil, you can adjust it for different plants. Some want moist soil others like it to become dry sooner.
Trial and error is necessary to make the right mix for your plants. In the same way, you need trial and error to learn if you are watering a plant appropriately. We hope this article helps you take care of your houseplant collection and save money.
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Hi! I’m Sophia, and I love plants – especially an expert in growing house plants. I stay in Chicago, United States of America, and through my blog and social media platforms, provide tips and tricks on how to grow healthy, vibrant plants indoors. Check out more here.