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Reusing Plant Drainage Water: Recover Leached Nutrients


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Watering plants is an essential task any plant owner has to perform on a routine basis to ensure the survival of any plant. A result of watering is excess or drainage water that collects at the bottom of the potted plant.

Reusing a plant’s drainage water helps reduce the amount of fertilizer we have to add to any particular plant since the drainage water will contain valuable nutrients which were leached from the soil during watering and can now once again become available to the plant.

After irrigation and a plant take in as much water as needed, the leftover water will gather to the bottom of the plant and go through the bottom into the saucer beneath. 

This drainage water contains the mineral ions that would return to the ground otherwise.
As a result, there are many benefits of reusing the water runoff from potted plants which we will discuss further in this article.

Benefits of Reusing Plant Drainage Water

Reusing Plant Drainage water

Reusing plant drainage water is a form of recycling, as we are not using clean water to irrigate the plant, but using what’s left behind. 

By doing this we can –

  • Recover nutrient and minerals which the plants did not get to utilize
  • Reduce the cost of purchasing more nutrients for plants
  • Reduce the amount of water being used to irrigate plants
  • Reuse other minerals which may bleached out of the soil during watering.

To take the guesswork out of determining how much moisture your soil has, you can use this cost-effective soil moisture meter from amazon.

XLUX Soil Moisture Meter

What Does the Drainage Water Contain?

The contents of plant drainage water vary a lot depending on the type of soil you use. 

However, most commonly, there are mineral ions and leached fertilizer. 

While the water is constantly escaping through the bottom of the pot, you may be able to see a white substance that gathers around the pot’s holes used for draining and sometimes on the surface of the soil. 

These are the leftover mineral salts left behind after the water has evaporated.

These same salts can be readded to water which is used for irrigation. 

But what are these mineral salts?
They are mineral ions such as magnesium, calcium, sodium, manganese, and other trace elements which are beneficial for the growth and development of plants.

The amount of minerals in the drainage water is dependent on how porous the soil medium is and also the amount of fertilizer that was added to the soil.

More aerated soil containing predominantly higher amounts of perlite can create a soil structure that is very porous.

What this equates to, is minerals and nutrients which were once available for the plants is now leached and held within the drainage water.

By reusing the drainage water you are also saving on fertilizers which you would have been adding to the soil in the first place.

Another added benefit is that the drainage water is not allowed to enter the water streams if it is thrown out. 

reusing plant drainage water 2

How to Recover Plant Drainage Water

First, you absolutely must have a plant pot with at least one hole in the bottom which helps plants with drainage and aeration.

A pot without one is essentially useless as there would be no way for the leftover water to escape and it will leave your plant soil constantly wet. 

Also, a plant’s roots need air and a pot without holes limits the amount of air they get, which may also lead to your plant’s roots rotting. 

Many garden pots come with large pans to stand them up on and gather the drainage water, called saucers. However, if you do not have a saucer, you can use other methods to recover the water.

One way is to use something called double-potting. This is where you have a smaller, commonly plastic, pot inside a larger one. 

The plant is in the smaller pot which would have some sort of drainage system, where the water would drip into the second pot. 

This water would then need to be drained often to stop it from harming the plant over a long period of time. 

Double-potting is useful if you have a pot without a drainage hole that may be made of foil or a non-plastic material. 

Drainage holes can also be placed on the sides of plant pots to aid in the removal of excess water. See our article on placing drainage holes on the sides of plant pots.

If you have an interior type of pot that does have holes in addition to the one without, you can get away with having a decorative or nice-looking pot without drainage holes.

When applying water to my plants, I use a cost-effective and durable watering can I got on amazon which makes watering fun and easy without making a mess. You can find it by clicking here.

MyLifeUNIT Plastic Watering Can

How to Reapply Drainage Water to the Plant

Plant drainage water at the bottom of a pot can technically be reused by the plant by just leaving it there and the plant soaks it up from the bottom again. 

This is practical if the saucer or catchment does not overflow. It is recommended that when the saucer is full that you simply use it by adding it to a plant that requires additional fertilizer.

This not only creates space for more water to drain out of the soil but prevents other insects such as mosquitoes from breathing in the stagnant water in the saucer.

This only works with pots that are submerged in their draining water when placed on a catchment or saucer plate.

Leaving the water to well up in the saucer leads to waterlogging and the accumulation of salts.

Waterlogging is where the soil and the root area is saturated with water and the roots don’t get enough air. 

Therefore, you would need to manually retrieve the drainage water from beneath your plant and apply it yourself to the plant. 

This makes sure you aren’t wasting the water and your plants are getting a share of minerals that are dissolved in the water that is lost from the soil after it travels through the plant pot.

Soil Types and Nutrients in Drainage Water

Depending on the type of soil you use for your plants, there are different minerals and nutrients that get dissolved in drainage water over time from when the water first enters the pot to when it is drained out. 

The most common nutrients found in most soils are magnesium, calcium, sulfur, potassium, and iron.

  • Magnesium is needed in metabolic functions and to form plant fats
  • Calcium helps the activity of enzymes and how permeable a plant’s roots are
  • Sulphur allows for amino acids to be formed for protein synthesis
  • Potassium is needed for the regulation of water in the plant and iron is responsible for the development of enzymes and their activity.

Plant drainage water is very useful – it is always good to reuse excess water – although using drainage water almost as a substitute for regular water can be very harmful to your plant in the long run. 

This is because, over time, salt in the soil will build up. Plants don’t grow very well in soil that has a high saturation of salt and the water essentially washes it out. 

Don’t let this fact deter you from recycling your drainage water, however, as there are still many benefits.

You don’t have to necessarily reuse the water on the same plant but use it in the garden or a raised bed

Drainage Water and Pets

The water which drains out from the plant pot may well up in the saucer beneath it.

This may pose a potential hazard since the minerals it contains may not be beneficial to curious pets.

Cats and Dogs are the most popular when it comes to pets in the household and in many cases, plant owners often stumble across their pets drinking from water welled up in the plant saucer.

Here is a more detailed article on what to expect if you suspect that your pet is drinking from the plant’s drainage water.

JayLea

JayLea has a passion for plants and has been gardening since 2015. He has valuable knowledge about gardening and houseplant care and can answer everyday practical questions that every plant owner has.

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