Photo by Teona Swift: https://www.pexels.com/photo/crop-gardener-showing-plant-sprig-with-roots-6913402/
Some plants can survive indefinitely in soilless mediums. This is any potting material that does not contain any decomposed biological matter.
Perlite (a type of volcanic rock) and plain water are some of the most common soilless mediums. As long as you load these mediums with enough nutrients and water, your plant will survive in them just as long as they would in a pot of soil.
Why grow houseplants without soil?
Mario Heller https://unsplash.com/photos/SvU9ZIW4KeA
Soil contains rotted biological materials and tends to cling onto any moisture it receives. By contrast, mineral mediums like perlite or sand have a crumbly texture. It is full of air pockets that supply oxygen to your plant’s roots.
Some plants prefer soilless mediums because they offer the root system ideal conditions. Chances are that your cactus will thrive better in a soilless medium. In the wild, they anchor themselves in extremely dry and sandy substrates, just like date palms and certain shrubs. These plants have adapted to survive on very little nutrients and water, so mineral mediums will suit them just fine.
Deserts aren’t the only places where we find plants that grow in little to no soil. Rainforests are home to specialized plants called epiphytes that have adapted to grow on tree branches. Because these habitats are so humid, epiphytic plants can absorb water and nutrients from the surrounding air and don’t have to be in contact with soil to obtain their life essentials.
Some orchids are epiphytes and gardeners can choose to grow them on pieces of bark covered in moss. This mimics their wild microhabitats on tropical trees. You don’t need to attach any soil to the bark, but the surrounding air must be really humid – bathrooms are an ideal location for bark-mounted orchids.
David Clode https://unsplash.com/photos/Y1ocPK_oSCw
Soilless mediums can work for all kinds of plants because you can easily adjust the type and amount of nutrients they contain or pH levels. In the US, Canada, and Europe, 95 percent of greenhouse vegetables grow in soilless media like synthetic fibers, which increase yields. Soilless media are also easier to sterilize, reducing the risk of pests.
While soilless potting mediums like perlite or synthetic fibers are naturally full of air pockets, this is trickier to maintain if you are growing in just water. If you are growing houseplants in water, you will need to top up the oxygen levels every couple of weeks so that the roots can maintain themselves and grow. This is easy since all you need to do is replace the water inside the container completely.
What about no potting medium at all?
But how long can plants go without potting mediums altogether - whether soil or soilless? The answer is not very long. Whatever material they are kept in, plant roots need an environment that supplies them with three things: oxygen, nutrients, and water. If you uproot your plant and leave them lying around without any one of these, they will die in a matter of weeks, if not days.