Do You Need Soil To Grow Plants? (Aero, Aqua, Hydroponics)


Managing plants grown in soil is a lot of work: fertilizing, digging, tilling, and weeding are part of the process.  This leads many gardeners to wonder if there is a way to grow their favorite plants indoors without soil. 

So, do you need soil to grow plants?  No, you do not need soil to grow plants if you use hydroponic, aquaponics, or aeroponic systems.  These systems provide water, nutrients, light, support, and warmth for plants without any soil.

Of course, these systems have found a way to provide plants with what they need for growth, even without soil.  Let’s get into the details of how these systems work, along with the benefits and drawbacks of each one.

Do You Need Soil to Grow Plants?

No – you can grow plants without soil.  However, you must still find a way to provide water, light, nutrients, support, and warmth as the plant grows.

The three main methods of growing plants without soil are hydroponics, aquaponics, and aeroponics.  Each one has its own unique way of providing plants with what they need, including:

  • Water – Some soilless systems place the roots of plants in water.  Remember that the water also needs to be oxygenated (there is oxygen between soil particles, so the plant roots need to get oxygen from the water instead).
  • Nutrients – These systems either dissolve nutrients in water (a nutrient solution) or spray a nutrient solution onto plant leaves (misting or foliar feeding).
  • Light – These systems can provide light by using LEDs or sunlight near windows or skylights.
  • Support – These systems usually let plant roots grow through a plastic mesh container, held in place by a larger container.  Otherwise, the roots will grow in materials such as gravel, perlite, or coconut husk, with nutrient solution washing through to feed the roots.
  • Temperature – These systems need to heat up the water and air to a temperature that allows for proper germination and growth of plants.

For more information, check out this article from New Mexico State University on growing plants without soil.

Let’s take a closer look at each of the three main methods of growing plants without soil, and how each one works.

Hydroponics

According to Purdue University, “Hydroponics is the practice of growing plants with nutrients and water but without soil.”

seed tray
You will need containers or trays (without the soil!) for a hydroponics setup.

In a hydroponic system, the plant roots are suspended in water or in a soilless medium such as:

  • sand
  • gravel
  • perlite
  • peat moss
  • sawdust
  • coconut husk
  • rockwool
perlite
Perlite is one growing medium that can be used as a soil alternative in hydroponics.

The water is recycled by pumps that move the water and aerate it to provide oxygen to plants.

Plants that are often grown in hydroponic systems include:

  • lettuce
  • tomatoes
  • peppers
  • cucumbers
  • strawberries
  • herbs

For more information, check out this article on hydroponic systems from the University of Massachusetts at Amherst.

Benefits of Hydroponics

One benefit of hydroponics is that the water can be reused, resulting in less waste.  This means hydroponics can be used to grow plants in places where soil quality is poor or water is in short supply.

Another benefit of hydroponics is that these systems can be used indoors to grow plants year-round.  As long as you have light, nutrients, and adequate temperature for your plants, they can continue to grow and provide a harvest.

Also, there will be no weeds to pull from your hydroponic system, since the seeds will not blow in or be carried in by birds or wind.

Since there is no soil, many plant diseases and pests are minimized in hydroponic systems, as long as you are careful about what you bring into the system.

This also minimizes the need for pesticides, meaning we can produce organic vegetables from hydroponics.

weeds
As long as you are careful, there should be no need to worry about weeds in a hydroponic system.

In addition, nutrient deficiencies are rare in hydroponic systems, since there are no floods or poor soil to deal with.

As long as you keep an eye on things by testing regularly, your plants should grow strong with all of the nutrients they need.

Also, hydroponic systems can be automated with the proper equipment, meaning that your system can go for a long time without any attention from you.

Finally, hydroponic systems require less space than traditional gardening, since plant roots do not need to stretch out so far to find nutrients and water (since they rest in a nutrient solution!)

For more information, check out this article on hydroponics from the Virginia Cooperative Extension.

Drawbacks of Hydroponics

Of course, there are a few drawbacks to hydroponic systems, so let’s mention those now.

First, if a disease does occur in a hydroponic system, then all of the plants grown in the system are potentially at risk.  The disease can easily spread through the nutrient solution to other plants.

Also, most hydroponics systems recycle the water by cleaning it and oxygenating it.  This requires pumps, and the electricity cost to run them can really add up.

In addition, a hydroponic system requires more technical knowledge than you would need if growing your plants in soil.

Finally, if your system automation fails while you are away, your plants can be damaged beyond the point where you can save them.

Aquaponics

According to the University of California at Davis, aquaponics is “the symbiotic cultivation of plants and aquatic animals in a balanced recirculating environment.”  (Basically, aquaponics is hydroponics with fish in the water).

aquaponics
Tilapia are a commonly grown fish in aquaponics systems.

Aquaponics is similar to hydroponics, except that these systems produce fish for harvest in addition to producing plants.

The idea is that the fish waste (in the form of ammonia, which contains nitrogen) in the water acts as a fertilizer, feeding the plants with nutrients.  The plants, in turn, clean out the waste from the water and provide clean water for the fish.

Some of the fish often grow in aquaponics systems include:

  • tilapia
  • rainbow trout
  • largemouth bass
  • yellow perch
  • bluegill
  • koi

Benefits of Aquaponics

One benefit of aquaponics is that you can raise a large amount of fish in a small space.  Since the water is cleaned by plants in the system, there is less worry about buildup of fish waste in these systems.

Another benefit of aquaponics is that relatively few fish can supply enough nitrogen for a large number of plants.  According to the University of Florida, 100 pounds of fish will supply enough nitrogen for 4050 lettuce plants or 540 tomato plants!

Of course, all of the benefits of hydroponics systems also go along with aquaponics systems, including less water use than traditional soil gardening, no weeds to pull, and system automation.

Finally, aquaponics can be more profitable than hydroponics, due to the ability to produce fish for sale in addition to fresh produce.

Drawbacks of Aquaponics

Of course, aquaponics has its own drawbacks.

One drawback of aquaponics is that the overall system is more sensitive than hydroponics.  In addition to making sure plants have enough nutrients and a proper pH, you must do the same for the fish in the water.  This makes aquaponics more of a balancing act than hydroponics.

Another drawback of hydroponics is that any disease will spread quickly throughout the fish in the system, since they are all in the same water.  However, this is true of any large-scale operation where many fish are grown in the same tank.

Aeroponics

In an aeroponic system, plants are grown in the air, with no soil and a small amount of water.  In these systems, a mist of nutrients and water is sprayed over plants in a growing chamber.

aeroponics towers
Aeroponics uses no soil and very little water to grow plants, using a mist to spray plants with the nutrients and water they need.

The content and timing of the nutrient spray can be adapted to maximize plant growth.  Aquaponics is something that NASA is looking into, in order to produce food with no soil and little water on long space voyages.

Benefits of Aeroponics

One benefit of aeroponics is that no standing water is required.  This means that no pumps are needed to recycle water and aerate it for plants and fish, as in hydroponics or aquaponics systems.

Another benefit of aeroponic systems is that use of resources is minimized.  This includes use of water, nutrients (fertilizer), and pesticides.

In addition, plants in an aeroponic system can be grown vertically (as in a tower garden), which saves precious space.

aeroponics towers
Aeroponics towers can grow lots of plants in much less space than traditional soil gardening. Imagine how much garden space you would need for the plants in just one tower!

Finally, aeroponic systems can be automated to some extent, reducing the need for labor and attention in these systems.

For more information, check out this article on aeroponics from Whole Plant Technologies.

Drawbacks of Aeroponics

As with any growing system, there are some drawbacks to aeroponics.

For example, the root chamber must be cleaned regularly.  Otherwise, contamination can occur, which can infect all plants with diseases.

Also, the nozzles that spray water and nutrients can become clogged, so they must also be cleaned regularly.

Conclusion

By now, you know that there are a few different systems you can use to grow plants without soil.  You also know about the benefits and drawbacks of each one.

I hope you found this article helpful – if so, please share it with someone who can use the information.  If you have any questions about how to grow plants without soil, please leave a comment below.

jonathon.david.madore

Hi, I'm Jonathon. I’m the gardening guy (not guru!) who is encouraging everyone to spend more time in the garden. I try to help solve common gardening problems so that you can get the best harvest every year!

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