Do Plants Need Soil to Grow? Are you new to gardening, limited in space, and wondering what you can use instead of soil? The answer might surprise you.
Not all plants need soil to grow, but they need specific environmental conditions to thrive.
The better question to ask is…
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Do Plants Need Soil to Grow?
Not all plants need soil to grow. Some do better in soil compared to other growing mediums. Plants need minerals and nutrients, such as nitrogen, potassium, and phosphorous. Soil is an effective way of delivering those nutrients cost-effectively. You can also use alternative delivery systems like hydroponics, aeroponics, and aquaponics to achieve the desired effect. However, these are only suitable for growing shallow-rooted plants. Plants with deep roots will always need soil, as will larger plants with spreading roots.
Why do Plants Need Soil?
Plants only need soil because of the nutrients and the hold the soil provides the plant roots. This way, plants can stand upright. But nutrients are also provided through water and watering. Roots can get hold in different mediums such as legal and other materials. Therefore, plants do not need the soil itself but the benefits it provides.
I grow many of my plants directly in water in a hydroponic system using a growing medium such as stone wool or hydroton.
What All Plants Need for Growth
Regardless of the type, every plant has five key elements to grow: light, water, air, heat, and nutrients.
Getting nutrients to a plant’s roots is easier done with soil.
Soil holds moisture, letting the plant drink what it needs. It also keeps the roots warm while providing the right amount and type of water.
Soil also delivers oxygen to the plant’s roots.
Nutrient delivery is better in soil because there’s more control over the pH (soil acidity) than other growing mediums.
Feeding fertilizers via soil is ideal as there’s a higher degree of control over N-P-K Values of plant food/fertilizer.
The core advantage that makes soil simpler for gardeners is easier control of the plant’s diet, ensuring it has everything it needs to thrive.
That’s why soil is the preferred growing medium for most plants.
Not to mention, there’s an abundance of it, and it’s the most cost-effective method of gardening even after you include the cost of fertilizing.
Other Methods of Growing Plants without Soil
Hydroponics
A hydroponics system swaps out soil for water. Not all plants do well when grown hydroponically, but those that do thrive.
These are typically used to increase crop yields and the year-round growing of shallow-rooted vegetables.
The water is oxygenated, providing support for the roots through the following mediums that won’t compact under consistent moisture:
- Rock wool
- Vermiculite
- Coco coir
- Peat moss
Light is still needed, as are pH control and nutrients.
The only difference to growing hydroponically is that the water is oxygenated.
In soil, air pockets allow the roots to get some oxygen. Pumps or an air stone can oxygenate the water. Without oxygen, plants drown.
The same happens in over-watered soil as a result of poor drainage.
Most hydroponics kits are designed to be used indoors, so you’ll need supplemental lighting.
As with all alternatives to soil-based gardening, there’s less support for root development. Hence, deep-rooted plants and vegetables aren’t suited to hydroponic gardening.
Aeroponics
Aeroponics is a sub-set of hydroponics, minus the growing medium to support the roots.
Instead, net pots, closed-cell foam rings, or other types of pots are used to suspend plant roots in the air. But this still provides support for the stems and roots.
Aeroponics works by misting the roots directly with a nutrient-rich solution rather than keeping them consistently submerged, according to Science Direct.
It is a more technical setup, requiring more maintenance to prevent mineral accumulation from clogging the jet sprays.
Generally, there are three types of aeroponics systems.
- Low Pressure
- High Pressure
- Ultrasonic Foggers
Home growers typically use a low-pressure system.
High-pressure systems are costlier and more technical as they create miniature water droplets less than 50 microns in size.
Ultrasonic foggers (known as fogponics) create finer particles that are easier for plant roots to absorb.
However, salt accumulation happens faster, so there’s more maintenance involved in fogponics.
Aquaponics
Aquaponics is a hydroponics system with fish. It’s essentially an aquaculture-hydroponic hybrid.
You feed the fish; the fish waste becomes the plant food.
No fertilizer is needed, although what is needed is pH adjustment to keep the fish and the plants alive.
Aquaponics is for food cultivation and not just for decorative purposes. This is different from growing freshwater aquarium plants that don’t contribute the same to an aquaponics ecosystem.
The purpose of aquaponics is to grow editable plants.
Which is Better: Soil or Soil-less Gardening?
Every method of gardening has its pros and cons. Soil is the most convenient and it’s easily understood.
There’s plenty of dirt, and you can replace it easily with a potting mix for most plants.
Hydroponics, aeroponics, and aquaponics are far more technical and incur more operational expenses. The main advantage of these is for year-round growing indoors.
Frequently Asked Questions On Soil-less Gardening
What Plants Will Always Need Soil?
Any plants with deep roots will always require soil. These include deep-rooted vegetables such as potatoes, sweet potatoes, carrots, onions, and turnips. The size of the spread and growth will also be a factor for indoor gardening. Naturally, space limitations will prevent larger plants from being grown in anything other than soil.
Can plants usually grown without soil be transplanted in soil?
You must be careful to avoid transplant shock, but you can certainly transplant plants from one medium to another. Starting seeds, seedlings, or cuttings indoors with hydroponics or aeroponics systems can be beneficial for getting a healthy start to root development. The biggest problem with transplanting to soil is transplant shock.
This can be minimized by keeping the soil conditions the same over time to allow the roots to acclimate to their new growing climate. Plant roots are regularly used as a nutrient-rich feed in a soil-less growing environment due to consistent moisture and watering.
When transplanting, adding mycorrhiza around the roots of the plant will help it absorb more nutrients from the soil. Once transplanted in soil, the plant should be watered immediately. After which, make gradual changes to allow the roots to acclimatize.
Daniel has been a plant enthusiast for over 20 years. He owns hundreds of houseplants and prepares for the chili growing seasons yearly with great anticipation. His favorite plants are plant species in the Araceae family, such as Monstera, Philodendron, and Anthurium. He also loves gardening and is growing hot peppers, tomatoes, and many more vegetables.