If you’re an avid home gardener like myself (well, mostly my wife!), you love to grow plants in different ways and offer plenty of fertilizer to help them along.
But what happens when you run out of one or the other.
Once, we ended up with extra hydroponic nutrients, and we wanted to help our soil plants along. This led to the question: Can hydroponics nutrients be used in soil?
After some research (and later testing ourselves), here’s what we found.
Hydroponic nutrients are safe to use with plants grown in soil. The nutrients offer nitrogen, phosphorus, potassium, and other nutrients needed for plant growth. However, we recommend you flush out your once per week to prevent salt buildup due to the high concentration.
Read on to learn more about hydroponic nutrients, why they are sometimes problematic, and how to use them properly in a traditional soil situation.
Table of Contents
Can Hydroponics Nutrients Be Used In Soil?
The hydroponic solution is usable with soil as it contains the same nutrients needed for soil plants, just in a different form.
Good nutrients are just good nutrients, after all.
Essential macronutrients include:
- Nitrogen
- Phosphorus
- Potassium
These are the “big 3” of growing plants, and they do the most work with helping convert sunlight into energy and converting energy into growth.
Phosphorus is the big one for seeds and root growth, while nitrogen is the big one for long-term health.
Read more about hydroponic roots and how to help them grow.
Micronutrients are smaller and help with more specific elements such as cell structure, strength, and overall health.
These include:
- Calcium
- Boron
- Copper
- Chloride
- Iron
- Manganese
The exact amount of each nutrient depends on the product, and the skilled gardener will be able to look at their plants and figure out what they need to grow better or fix a certain health issue.
This is where the different types of fertilizers, enhancers, or nutrients come in.
For example, a root enhancer will have more phosphorus and potassium and include some humic of fulvic acid to help with water retention.
With soil plants, fertilizer is critical in the long-term as the soil will lose its nutrients to the plant over time.
Hydroponic plants only get their nutrients from the nutrient-rich water, so it’s even more important.
And as we mentioned above, they can cross over, but you need to know how to get this done, starting with the main differences.
Difference Between Hydroponic Nutrients And Soil Nutrients
These nutrients are needed for any plant, but soil fertilizer and hydroponic fertilizer come in different forms.
In general, the main differences between hydroponic nutrients and soil nutrients come down to form, nutrient density, nutrient spread, and refilling or flushing.
Here’s a quick reference table for the differences with a bit more detail in the next section:
| Soil Fertilizer | Hydroponic Nutrients | |
| Form | Solid or liquid form | Almost-exclusively liquid |
| Nutrient Density | Small amount nutrients | High levels of nutrients |
| Nutrient Spread | Fewer types of nutrients | All nutrients needed |
| Refill/Reuse | Only on occasion | Weekly refill or flushing |
| Purpose | Supplement the soil | Provide all nutrients |
Form
Soil fertilizer comes in several different forms, including solid and liquid.
Hydroponic fertilizer is almost exclusively liquid, and if it’s not, it requires you to mix it in with water first.
Nutrient Density
The purpose of soil fertilizer is to enhance what’s already in the soil and make up for the difference.
As such, it doesn’t usually feature as high an amount of nutrients.
Hydroponics needs all the nutrients from the solution, so expect a generally higher amount of everything.
Nutrient Spread
Along the same lines, soil fertilizer doesn’t need every nutrient under the sun; the soil has some in it, too, especially if you used good peat or other potting soil.
Hydroponics grow mediums don’t usually have any nutrients in them, so every nutrient comes from the solution.
As a result, hydroponic nutrients have more overall nutrient types.
Refilling Flushing
Typically, soil fertilizers only need to be used on occasion, but hydroponics need to be flushed out and refilled constantly.
Problems With Hydroponic Nutrients In Soil
Using hydroponic nutrients in the soil isn’t an instant win; there’s a bit of danger involved to your plants.
Nutrient locking is when a plant’s roots become oversaturated and can’t accept any more.
This condition, if left on its own, will end up killing most plants.
It’s largely caused by two main problems:
- Too high salt content
- Too many nutrients at one place
The hydroponic solution adds to both of these issues.
Over time, the solution consolidated in the soil near the roots.
As the salt increases from this, it throws off the EC in the roots.
I won’t get into the details (it has to do with electricity, believe it or not), but when the EC is too high, the roots can’t absorb nutrients.
The cells won’t absorb them at all!
A similar thing happens with the concentration of nutrients.
The parts of the root that absorb the nutrients get blocked.
So while it may take in water, hydroponic plants won’t actually use the nutrients.
It’ll spit them right out again.
This is why changing the water fully and supplementing it with fresh, untreated water throughout is recommended.
With soil, it causes problems even faster if you’re not careful.
We’ll talk about how to help in the next section.
How To Use Hydroponic Nutrients In Soil
Fortunately, armed with the right information, it’s not tough at all to use the hydroponic solution in soil-grown plants.
Mix up the solution with water exactly in the directions described.
You don’t need to adapt it at all.
Then, pour the solution carefully onto the soil around your plants’ roots.
When the soil is damp, stop. You don’t want to use too much.
Then, leave it be for a week.
Don’t add any more.
After a week, flush the soil to remove the salt buildup and unabsorbed nutrients by saturating the soil with fresh, untreated water.
Leave it again for a week. (It’s OK to still water the plants).
If you wanted to add more hydroponics nutrients after another week, go for it, but it’s probably not needed.
The flushing removes the danger of too much salt and nutrients, and mixing it as you normally would for a hydroponic plant still give your traditional plant a shot of good nutrients to help it grow stronger.
For the reverse situation, check out our guide to using fertilizer in hydroponics.
Choose The Right Hydroponic Nutrients For Soil
Most hydroponic solutions will work just fine with soil, but there are few brands that work better than the rest. Here is what we recommend:
- Flora Gro – Costs a bit more, but it’s widely used and popular.
- Maxi Gro – Jammed pack with nutrients when your plant needs to grow fast and large.
- AeroGarden Liquid Nutrients – Affordable and reliable.
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