Using Hydroponic Nutrients in Soil Plants? (Don’t Do It!)

Are hydroponic nutrients effective on soil-grown plants? Many gardeners, like me, are curious to see if hydroponic nutrients can supply the necessary minerals to support plant growth and development. Now, I know you’re here because you’re curious too!

Hydroponic nutrients are not recommended for plants grown in soil. This is because they can cause salt buildup given their different composition from soil fertilizer. Although both hydroponic nutrients and soil fertilizers contain essential plant nutrients, they cannot be used interchangeably.

What are the similarities and differences between these two nutrient sources? What are the distinctions between them? Can they be used interchangeably? These are the major questions that will be addressed as you continue reading.

Why Should Hydroponic Nutrients Not Be Used in Soil?

Salt buildup may occur in soil when the hydroponic nutrients are applied with watering because one cannot control the nutrient amount. The application of more nutrients leads to the accumulation of mineral salts that could block the roots. This is contrary to soil fertilization where one can calculate and weigh the right amount of fertilizers.

You can use hydroponic nutrients in soil only as a supplement. Even then, it should not be frequently applied to soil-grown plants. This is because the nutrients contained in these fertilizers can solidify and accumulate in the soil.

Water and oxygen will mobilize efficiently within the soil system if this occurs. The salts will make it more difficult for water and oxygen to reach the roots. Thus, using hydroponic nutrients as fertilizer in soil is not recommended.

It is also inefficient to use hydroponic nutrients for soil-grown plants because they have a tendency to simply flow through the soil because they are commonly used in conjunction with watering.

So you’d basically be washing them away through the drainage holes of potted plants—wasting your money, time, and resources!

The Only Case It is Okay to Use Hydroponic Nutrients for Plants in Soil

Hydroponic nutrients can be used for plants grown in soil only as supplement fertilizers. Such supplements can be used only after a heavy rain that might have washed away any soil nutrients previously applied.

The three essential macronutrients for optimum plant growth are nitrogen, phosphorus, and potassium. In almost all commercially-sold nutrients solutions, these are present in varying ratios.

Some of the fertilizers (whether for soil or hydroponic plants) are labeled with an equal amount of these three. For example, 14-14-14. Meanwhile, other types of fertilizers have more nitrogen and are used for the vegetative stage of plants.

Those very nutrients, when used correctly and in perfect balance with each other, will guarantee the development of leaves, proper structure, flowers, and fruits.

If you are going to use hydroponic nutrients in your soil-grown plants, I recommend using it only once a week or once every 2 weeks. Do not use them every day because it might result in salt buildup!

   For a detailed explanation on the components of hydroponic fertilizers, head to our article on hydroponic nutrients.  

The 3 Main Differences Between Hydroponic and Soil Nutrients

Hydroponic nutrients and soil fertilizers are different in terms of common form, strength of fertilizer, mode of application, and complexity of use.

1. Common Form

Most hydroponic nutrients are available in liquid form, whereas most soil fertilizers are in granular or powdered soil form.

You may wonder why most hydroponic nutrients are in the liquid form. But if you look at it, the answer is quite simple. It is because they are easier to apply in a water-based system, such as hydroponics.

   Explore more about this in our article on how are hydroponic nutrients made? 

On the other hand, solid (granular or powdered) fertilizer forms are used in soil-grown plants since they can be mixed with the soil. Moreover, they will dissolve overtime as you water your plants.

2. Mode of Application

General hydroponic nutrients can be applied in its diluted form along with watering. In contrast, most soil fertilizers work well with basal application, which is the incorporation of granular nutrients with the soil before or during planting.

When using granular soil fertilizers, it is commonly applied in the soil as a mix or a side dressing.

On the other hand, since hydroponic nutrients are liquid in form, they can be added as supplements in water.

3. Complexity of Use

Hydroponic nutrients need to be checked for their physico-chemical properties such as pH and electrical conductivity before use. On the other hand, soil nutrients can be applied as-is, making it the simpler way to fertilize plants.

If you are not familiar with the terms above, let me help you better understand them!

When we say pH, it is the measure of acidity and alkalinity of a certain solution. Common examples of compounds with low pH (acidic) are vinegar, muriatic acid, and lemon juice. Meanwhile, high pH (basic or alkaline) compounds are bleach, detergent, and baking soda.

Too low or too high pH value can negatively affect your plants.

Electrical conductivity (EC) is the amount of nutrients in a specific solution. This is commonly used in hydroponics to measure the salt concentration in a solution. When you have a high electric conductivity, you also have high salt and high concentration of nutrients.

Generally, a high EC indicates that your hydroponic nutrient has sufficient nutrients that are beneficial for your plants. However, caution must be taken into consideration since too many nutrients can also cause mineral buildup.

These are the questions you need to ask before applying a hydroponic solution to a soil-grown plant:

• Will this application of hydroponic nutrients affect the pH of my soil?
• Will that change in pH be beneficial for my plant? (Most of the time, it’s not!)
• Will the application of hydroponic nutrients elevate the salt concentration in my soil?

Can You Use Hydroponic and Soil Nutrients Interchangeably?

Hydroponic fertilizers should be used for soil-grown plants exclusively as supplement fertilizer. On the opposite, soil nutrients can be dissolved in water to serve as base solution for your hydroponic plants regularly.

There are also general plant nutrients that can be safely used to fertilize both hydroponic and soil-grown plants.

An example of this is Masterblend which is a fertilizer that can be used both in soil and hydroponic gardening.

Masterblend (4-18-38) is best for fruiting veggies since it contains higher levels of phosphorus (18) and potassium (38) that help to ensure fruit crop harvest quality.

On Amazon, you can purchase a pre-mixed Masterblend like the one below containing 12 grams of the nutrient to be dissolved in 5 gallons of water.

Masterblend Tomato & Vegetable Fertilizer Plant Nutrients Fertilizer Combo Kit -...

Check The Price

FAQs

Do I need to dilute hydroponic fertilizers before using them in plants?

Because hydroponic nutrients are highly concentrated, they must be diluted in water before they are used as a supplemental nutrient solution. Using undiluted hydroponic nutrients can result in nutrient toxicity. Nutrient toxicity occurs when there are too many nutrients in the soil which could lead to yellowing, browning, and eventual plant death.

Does hydroponics yield better than soil gardening?

In terms of yield, hydroponics is a more efficient system to use and thus considered better overall. This is because it conserves space while producing almost twice the harvest one can get using soil gardening.

Why do plants grow faster in hydroponics?

Plants grown in hydroponics grow faster because the water is oxygenated and nourished directly. These essential resources are delivered to plant roots in a concentrated manner. This is contrary to traditional gardening in soil where nutrient resources are dispersed among soil particles.

Summary of Using Hydroponic Nutrients in Soil-Grown Plants

Using hydroponic nutrients to fertilize soil-grown plants is not recommended because the soil is already rich in a variety of nutrients. Salt buildup can occur as a result of using hydroponic nutrients on plants in soil which can slow down plant development due to root blockage.

Hydroponic and soil nutrients are similar in the sense that they both contain the essential macronutrients needed by the plants for their biological processes. On the other hand, they differ in terms of their common form, mode of application, and complexity of use.

Sources

• “Hydroponics Systems and Principles Of Plant Nutrition: Essential Nutrients, Function, Deficiency, and Excess” by Sanchez, E et al. in Pennsylvania State University
• “Fertilizer Storage and Handling” by UMass Extension Greenhouse Crops & Floriculture Program in University of Massachusetts Amherst
• “Hydroponics” by Shrestha, A and Dunn, B. in Oklahoma State University
• “Nutrient Deficiency and Toxicity” by Montana State University