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Do Plants Need Soil to Grow? Let’s Dig Deeper

Do Plants Need Soil to Grow?  Let’s Dig Deeper

New to gardening, limited on space, and wondering what you can use instead of soil? 

The answer might surprise you. 

Not all plants need soil to grow, but they all need specific environmental conditions to thrive.

The better question to ask is…

 

Why Do Plants Need Soil to Grow?

Not all plants need soil to grow. Some just do better in soil compared to other growing mediums. What plants need are 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. 

 

What All Plants Need for Growth

Every plant, regardless of the type, has the same five key elements they need 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 with 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, as well as 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. 

It is a more technical setup, requiring more maintenance to prevent mineral accumulation clogging the jet sprays. 

Generally, there are three types of aeroponics systems. 

  • Low Pressure
  • High Pressure
  • Ultrasonic Foggers

A low-pressure system is typically used by home growers. 

High-pressure systems are costlier and more technical as they create miniature water droplets less than 50 microns in size. 

Ultrasonic foggers (better known as fogponics) create even 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 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 potato, carrots, onion, and turnip. The size of 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 will need to be careful to avoid transplant shock but you can certainly transplant plants from one medium to theoter. 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 a period of time to allow the roots to acclimatize to their new growing climate. In a soil-less growing environment, plant roots are used to a nutrient-rich feed regularly due to consistent moisture and watering. Adding mycorrhiza around the roots of the plant when transplanting 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.