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Adding Fertilizer When Bottom Watering: Here’s how to do it

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Fertilizing plants is one of the most essential parts of plant care there is and many times you may not know where to start especially when bottom watering.

When bottom watering, a water-soluble fertilizer should be added with the water once a month during the growing season. Adding the fertilizer with the water allows the nutrient to travel upwards and soak into the soil during the normal watering regime.

Bottom watering stimulates root growth and by adding fertilizer when doing so, can help boost plant growth at the same time.

However, there are some key things to consider when fertilizing to ensure you are doing it right which we are going to reveal further in this article.

How Much Fertilizer to Add?

Plant absorbing water from bottom watering

Houseplants need fertilizer because they don?t have the conveniences of nature which naturally adds nutrients to the soil from rainfall, decaying leaves, and dead insects.?

Adding fertilizer when bottom watering replicates nature’s processes by introducing beneficial nutrients to the plants.

The amount of fertilizer added to plants should be very small. For example, for an all-purpose inorganic soluble fertilizer such as Miracle grow (24-8-16), you will want to mix half the recommended amount to the mix per gallon of water.

Plants use only a very small amount of fertilizer to carry out their biological functions to grow healthy.

There are many different types of fertilizer out there and their NPK numbers can range between 0 to 30% per volume depending on the fertilizer.

If you use inorganic fertilizer, you should mix half the recommended amount of fertilizer to the mix because the NPK nutrient mix is usually way high up in the (10 to 30) range (eg. 20-20-20) which may be too much for your plant to bear.

On the other hand, if you are using an organic fertilizer such as compost or vermiculture you can add the recommended amounts to your soil as they are less concentrated in the NPK range, being somewhere in the NPK range of (2-2-2) or even (1-2-1).

Organic fertilizer can be added using the recommended quantity per volume of liquid. 

An additional fact of these organic fertilizers is that they also add beneficial organisms such as bacteria and fungus into the soil which can also help boost the plant’s health by improving the soil quality.

I have had the best results when growing healthy plants by using this Miracle-Gro fertilizer on indoor and garden plants. It’s excellent value for money and will last a long time.

Miracle Grow Soluble Fertilizer

How Often Should You Add Fertilizer?

Plants should be fertilized during the growing season which ranges from the beginning of spring straight till the end of fall. The frequency of fertilization is dependent on the particular plant in question.?

Although on some fertilizer packaging you may find it saying to fertilize once a month or some even as often as every time you water. 

You should always follow your plant?s growth cycle and in some cases it nutrient deficiency before adding fertilizer.

Slow-growing plants should be fertilized less frequently than plants with a fast growth rate.

Additionally, when the plants are not growing during the dormant season or the winter months you should not be fertilizing as the plant will not be using much of it. 

What will actually happen is that the soil will build up with salts which will harm the plants.

Fertilizer application is something that has to be taken with a pinch of salt. Pun intended.

Plants don?t require much fertilizer and many plant owners often find themselves rushing to add fertilizer whenever the plant shows signs of stress or yellowing of leaves. 

Pro Tip

The first thing you should do when a plant seems stressed, is to get the plant to some natural light, water and monitor its condition before adding fertilizer. More times than not, when fertilizer is added during plant stress, the plant ends up dying.

Interested in bottom watering trays? I have found durable trays which worked well for all my plants. You can click here to see them on amazon.

10 Plant Growing Trays

How to Fertilize when Bottom Watering – 

When bottom watering a water-soluble fertilizer should be used.?

The fertilizer should be fully dissolved in the water so that it will move with the water up into the soil to meet the roots.

Note: the soil should be watered partially before adding fertilizer to prevent the roots from being burnt by the diluted fertilizer. 

  1. Add a ? teaspoon of water soluble inorganic fertilizer to a gallon of water or the recommended amount of organic fertilizer. 
  2. Mix until all the fertilizer is dissolved
  3. Place your plant on a flat open container for bottom watering
  4. Firstly fill the container with 1 cm of water for the soil to absorb and become moist
  5. After 10 minutes remove the plant
  6. Remove the excess water from the flat container 
  7. Place the plant back into the empty container
  8. Pour fertilizer up to 1 inch in height and allow to sit for 10 minutes 
  9. Remove the plant and allow excess water to drain out.

One of the downsides when bottom watering is that because the plants are being watered from the bottom up, salts are likely to build up over time. 

When compared to conventional watering where the water moves downwards and out the plant pot, the upward water movement prevents excess salts from being leached out and eventually may cause a build up of salt which may burn and harm the plant.

As a result, it is recommended that you water your plant the conventional way from time to time to prevent salt build-up in the soil.

See our complete guide for bottom watering plants?which gives easy-to-understand details with?step-by-step instructions.

Should You Fertilize Before or After watering

It is recommended that you fertilize during watering ensuring that the soil is watered first before adding the fertilizer. 

This is because you don?t want to add fertilizer alone, no matter how much it has been diluted, directly to the soil and then plant roots.

Therefore, fertilizer should be added after you water and the soil is fully moist.

If the dissolved fertilizer is added alone the concentration of the fertilizer can end up burning the stems and roots of the plant, which will lead to yellowing of leaves and sometimes even death of the plant.

Plants do not only absorb water but they also take up nutrients during the process through the hairs of the roots which spread out throughout the soil.

You should also be mindful of the type of water that is being used to bottom water your plants as there can be differences in mineral content as well as pH, which can affect the soil and plant.

fish food as fertilizer

Should the Fertilizer be Added at the Bottom or on Top?

Fertilizer can be added from the bottom while bottom watering or from the top while watering through conventional methods.

Although we talk about how to fertilize by watering from the bottom. This method poses a risk to the plants in the long run.

This is one of the problems plants face if they are constantly being watered from the bottom. 

The lack of water flow through the soil and out through the bottom can cause salts to build up within the soil which can cause burns to the plant as previously discussed.

Therefore it is recommended that as part of your watering regime, although you may like bottom watering, you should switch it up sometimes and allow water to flow conventionally through the soil and out through the saucer to ensure that there is no build-up of salts over time.

The Takeaway

Bottom watering is a great way of promoting healthy root and plant growth. 

Adding fertilizer while bottom watering stimulates better root growth and should be done during the watering cycle every one to two months with a diluted solution of inorganic fertilizer or the recommended dose of organic fertilizer. 

Faster growing plants require more frequent fertilizer addition than their slower-growing counterparts and should be fertilized only during their growing period.?

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