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One of the reasons vertical gardening is becoming increasingly popular is that they are very easy to maintain compared to other types of conventional gardening. In addition to taking up less space, being generally more sustainable, and costing less to run, they also require far less soil (if any) to grow plants effectively.
Whether a vertical garden uses soil or not depends on the type of system and technique used for growing. For example, an aeroponic tower garden does not use any soil whereas a vertical container system is likely to use soil.
In this article, we will examine the different types of vertical garden systems and explore which of them require soil to grow plants and which do not. By the end, you will be well-placed to know which soil-based or soil-less system is right got you. Let’s get on with it!
Do plants even need soil to grow?
Plants do not need soil to grow. However, they cannot grow without the necessary benefits that soil provides. Plants need nutrients, protection from adverse temperatures, a supply of moisture, and oxygen around the roots.
Thanks to smarter gardening techniques it is possible to provide these things to plants without the need for soil.
Soil vs. soil-less vertical gardens
Before we examine the different types of vertical garden systems and whether or not they require soil in order to grow plants, let’s first examine the main types of vertical garden growing methods.
1. Vertical gardening systems that use soil
Vertical gardening isn’t always about high-tech solutions that use no soil, little water, and automated growing technology. There are plenty of vertical gardens that use soil in the same way as conventional container gardening.
In a vertical garden, the main difference is that the containers are stacked vertically on top of one another in tiers.
Even so, container-based vertical gardens don’t tend to use a lot of soil. This means that vertical gardens are excellent for growing herbs that have shallower root systems. While it’s possible, I find it more difficult to grow deeper root vegetables like potatoes or carrots.
2. Hydroponics systems that do not use soil
The art of growing plants without using any soil is called hydroponics. There are many different types of hydroponics systems, which I’ve written about extensively on this site.
In a hydroponic vertical garden system, plants are fed on a nutrient-rich solution that is pumped directly over the roots, usually by an automated irrigation system.
Instead of soil, roots are often supported by a porous substrate or growing medium, like rockwool or coco coir, that holds them in place.
3. Aeroponics systems that don’t use soil
Another vertical gardening method that requires no soil is aeroponics. Plants in aeroponic systems are held in place by a special foam and simply suspend their roots in the air within specialized, self-contained growing units.
The roots of each plant are not suspended in water and are instead periodically fed with a nutrient-laden mist they dangle in the air.
Which specific types of vertical gardens use soil?
Now that we have understood which vertical gardening techniques use soil and which do not, let’s examine each type of vertical garden system.
Stacked ‘container’ systems
There are quite literally thousands of ways you can create a stackable ‘container’ vertical garden system. Perhaps the cheapest and easiest vertical garden, container systems can be created using just about anything from plastic bottles to wooden pallets.
As the name suggests, the system is simply created by stacking containers above one another. These containers do require soil (of varying quantities depending on the size of the container) to grow plants. Container systems use soil in the same way as any other container garden.
Obelisk and Trellis Systems
Like staked container systems, the use of an obelisk or trellis to grow vining plants upwards around a frame also uses soil just like a traditional garden. These types of vertical garden systems can be used in containers or used to support plants that are planted directly into the ground soil.
Green ‘living’ wall systems
Green ‘living’ walls are a popular type of vertical garden system that fixes modules against a wall that contains soil in which plants – such as succulents – are grown for aesthetic purposes.
Green living walls do use soil. However, it is possible to use other growing mediums can be used to support the roots of plants. Only a limited amount of soil is used throughout the system, however.
Which types of vertical gardens don’t use any soil?
One of the main reasons I love vertical gardening is because it feels futuristic. And what could be more futuristic than growing plants without any soil at all? There are several vertical gardening systems that use no soil – not a single grain.
As futuristic as it sounds, it’s actually pretty simple.
Hydroponic Vertical ‘Tower’ Garden Systems
My hydroponic tower is my pride and joy and is one of the most efficient ways that I can grow herbs, leafy greens, and even vegetables. One of the best things about it is that it uses no soil whatsoever. None. That’s the beauty of hydroponics.
The tower contains holes in which seed pods made up of soilless growing medium and substrate are placed. The roots of the plants (when grown) are then simply washed in nutrient-rich water that is periodically pumped up from the reservoir below.
No soil is needed for this process, making a hydroponic tower one of the most efficient and cleanest ways to grow plants at home.
Home Smart Gardens
Sticking with hydroponics, there has been a surge of indoor home ‘smart garden’ systems in the last few years which allows pretty much anyone to grow plants in their kitchen without using any soil or creating any mess.
Most of these smart gardens utilize hydroponics, keeping the plant’s roots flooded with nutrient-rich water from the reservoir at the base of the system. No soil is used, making it a clean and efficient system with which to grow herbs and leafy greens for personal use.
Aeroponic Growing Systems
Aeroponic growing systems do not use any soil. Instead, plants are suspended (either inside vertical growing towers or horizontal tubes) with their roots exposed. The roots are then ‘misted’ with nutrient-rich moisture at regular intervals by water from a special sprinkler below the roots.
Aeroponics is arguably one of the most efficient ways to grow plants and uses up to 95% less water and 100% less soil than traditional forms of gardening.
How often should you replace the soil in your vertical garden?
In vertical garden systems where soil is used it should be refreshed or replaced every other year or so. Over time, compost will break down and lose its value. Replacing the soil completely, or at the very least, replacing one-third of existing compost and roots with fresh compost every two years will keep plants healthy.
So what have we learned? We know that plants do not need soil to grow. We also know that there are many forms of vertical gardening systems that do not use any soil at all. Conversely, if using simpler vertical gardening techniques like vertical container systems or even green ‘living’ walls, then soil is used more conventionally.
If you’re a bit of a tech nerd (like me) then you may wish to purchase or build a vertical tower garden or smart garden system that uses no soil at all. The possibilities are out there and open to you.