How can plants grow without soil?

Basil growing in a net pot, white roots submerged in water, and no soil in sight: at first glance, it seems almost impossible. Yet, a plant does not necessarily need soil to grow. It needs what soil usually provides, along with a few additional resources.

Understanding this difference is the best way to discover hydroponics, without believing that simply placing any plant in a glass of water is enough.

What does soil really do for a plant?

In a traditional garden, soil serves several functions: it anchors the roots, retains some water, contains or exchanges nutrients, and provides air and a home for living organisms. Roots draw water and minerals from it.

But soil itself is not the food that the plant "eats". Much of the matter produced by the plant comes from the carbon it captures from carbon dioxide in the air through photosynthesis. Water and minerals complete this process.

If another system provides the mechanical support, water, nutrients, and oxygen that the roots need, the plant can therefore grow without soil.

How does hydroponics work?

Hydroponics involves growing plants without soil by providing the roots with a water solution containing the necessary nutrients. Depending on the system, the roots may be partially submerged, receive a circulating stream of solution, or be regularly watered by a closed-loop system.

A plant does not necessarily float freely: a net pot and a hydroponic sponge or another suitable support can keep the young plant in place.

The nutrient solution must be prepared correctly. Tap water alone does not always provide all the minerals needed for a long-lasting crop. That is why hydroponic nutrients suited to the plants and their growth stage are generally added.

Where do the nutrients come from if the plant has no soil?

In nature, roots absorb minerals in dissolved forms from the soil water. In hydroponics, these elements are provided directly in the nutrient solution.

These include nitrogen, phosphorus, and potassium, as well as calcium, magnesium, iron, and other elements that plants need in smaller quantities. Each plays a different role in growth, leaf formation, or cellular function.

Therefore, "soil-free" should not be confused with "nutrient-free". A hydroponic garden requires the right dosage, suitable water quality, and sometimes monitoring of the pH or the concentration of the solution.

To learn more, our guide explains what hydroponic nutrients are used for and how to dose them.

Can roots breathe underwater?

Yes, but under one essential condition: they must be able to access oxygen. Root cells need it to function, just like the plant's other living tissues.

In some systems, part of the roots remains in contact with the air while another part draws water and nutrients. Other setups use circulating solution or appropriate aeration. The solutions vary depending on the technique.

A root completely submerged in insufficiently oxygenated water may eventually run out of air. This is one of the reasons why a reservoir should not be filled beyond the recommended level or why a pump's operation should not be changed at random.

The absence of soil does not prevent root diseases. A poorly maintained system or poorly managed water can also cause problems.

Why is light still essential?

Light provides the energy that allows the plant to perform photosynthesis. It uses water and carbon dioxide, in particular, to make the organic compounds necessary for its growth.

In an indoor garden, a window can provide some of this light, but its intensity varies with the season, orientation, and weather. Additional horticultural lighting can be useful when natural light is insufficient.

A plant placed in a perfect nutrient solution will not develop properly if it lacks light over time. Conversely, a powerful lamp cannot compensate for a lack of water, oxygen, or minerals.

What is a germination sponge used for?

A seed must be able to germinate in a suitable environment: moist enough, but also allowing access to oxygen. A germination sponge takes on the role of the support normally played by potting soil at the beginning of cultivation.

It helps keep the seed and young plant in place. As the roots develop, they grow through the support and reach the water or nutrient solution, depending on the design of the device.

The net pot keeps the whole thing in the growing area. Sponges and net pots must be the right size: there is no universal compatibility between all hydroponic accessories.

You can generally choose your own seeds and seedlings, as long as the species and varieties match the space, light, and conditions of your setup.

Can all plants grow without soil?

Many species can be grown without soil, but not all are suitable for the same system or space. Lettuce and some herbs are often good starting points. Tomatoes, cucumbers, or chili peppers can also be grown hydroponically, provided you have enough space, light, and nutrients, among other things.

Very large plants, those with long growth cycles, or those with significant root requirements need setups better suited than a small kitchen appliance.

Therefore, you do not choose a plant simply because it is "compatible with hydroponics": you primarily choose a plant compatible with the actual setup you have.

What are the advantages and limitations of growing without soil?

Growing without soil avoids handling potting soil in the kitchen and can make harvesting small quantities of herbs or lettuce particularly convenient. Roots are sometimes easier to observe, and nutrition can be adjusted more precisely when the system allows it.

On the other hand, the setup always requires attention. You must monitor the water level, add nutrients, clean the accessible components, and check the light and the condition of the plants. Systems equipped with a pump or lighting may also consume electricity.

Hydroponics is therefore neither magical nor completely autonomous. It is another way to meet the biological needs of plants.

How to start growing without soil at home?

To get started, choose lettuce seeds or an herb suited to your space. Prepare a net pot and a hydroponic sponge compatible with your equipment. Follow the instructions to moisten the support, prepare the nutrient solution, and turn on any lighting.

Then observe the roots and new leaves. Growth cannot be judged in a day: you must give the plants time to germinate and develop while regularly checking the conditions.

If you want a system designed for the home, you can discover Belverdia hydroponic gardens, choosing a format that is consistent with your crops and space.

Key takeaway: the plant needs resources, not necessarily soil

A plant grows without soil when its environment provides the essential elements: water, minerals, light, carbon dioxide, oxygen for its roots, and a suitable support. This is what hydroponics makes possible.

The principle is simple, but balance matters. A water reservoir does not automatically replace a garden: it is the combination of well-suited conditions that allows your plant to develop and, eventually, be harvested in your kitchen.