Hydroponics 101: How Growing Without Soil Actually Works
A ground-up explanation of what hydroponics is, why plants grow faster without soil, what they actually need to thrive, and which system type fits your space and goals. Written for complete beginners with no prior gardening experience.
Last updated
If you've ever wondered whether you can grow fresh food in an apartment with no outdoor space, no garden bed, and no prior gardening experience - the answer is yes, and hydroponics is how.
This guide explains what hydroponics actually is, why plants grow faster without soil, and what the basic concepts mean so you can make confident decisions about getting started.
What hydroponics is (and isn't)
Hydroponics is growing plants in a nutrient-rich water solution instead of soil. That's the whole concept. The word comes from Greek: hydro (water) + ponos (labor) - literally "water working."
What soil normally does for plants:
- Anchors roots physically
- Holds water and delivers it gradually
- Contains minerals that dissolve into water and get absorbed by roots
- Hosts microbial communities that break down organic matter into plant-available nutrients
In hydroponics, you replace all of that deliberately:
- Roots are anchored in inert media (rockwool, clay pebbles, net pots) or simply suspended
- Water is delivered continuously or in timed cycles
- Minerals are dissolved directly in the water at precise, known concentrations
- Beneficial microbes can be added intentionally
Why plants grow faster without soil
The speed advantage of hydroponics is real - typically 30–50% faster than equivalent soil growing - and it comes from eliminating search costs.
In soil, a plant root must grow and branch outward through the substrate to find nutrients and water, spending significant energy on root expansion. In a hydroponic system, nutrient-rich, oxygenated solution is delivered directly to the root surface. Roots become smaller and more efficient. The energy the plant would have spent searching for nutrients goes into leaf and fruit production instead.
The oxygen factor matters too. In waterlogged soil, roots suffocate because oxygen can't reach them. In a properly aerated hydroponic reservoir, dissolved oxygen is maintained at levels higher than most soils, which accelerates all root metabolic processes.
What plants actually need
Every plant needs the same six things, regardless of growing medium:
Light - the energy source for photosynthesis. Plants convert light into sugars that power all growth. The amount needed varies by plant type: leafy greens need less than fruiting plants.
Water - the transport medium for nutrients and the primary component of plant cells.
Carbon dioxide (CO2) - absorbed from air through leaf pores. Ambient air (400 ppm CO2) is adequate for home growing.
Nutrients (macronutrients and micronutrients) - the mineral elements plants need in varying quantities. In hydroponics, you provide these in solution:
- Macronutrients: Nitrogen (N), Phosphorus (P), Potassium (K) - needed in large amounts
- Secondary macros: Calcium (Ca), Magnesium (Mg), Sulfur (S)
- Micronutrients: Iron, Manganese, Zinc, Boron, Copper, Molybdenum - needed in trace amounts
The right pH - most plants absorb nutrients best when the solution pH sits between 5.5 and 6.5. Outside this range, nutrients become chemically unavailable even if they're physically present in the water. This is called nutrient lockout.
Support - physical anchoring for the root system and stem.
The three numbers you'll hear constantly: pH, EC, and PPM
pH is a measure of acidity/alkalinity on a scale of 0–14. Pure water is 7.0 (neutral). Most hydroponic crops want 5.8–6.3. You measure this with a pH meter and adjust with pH Up (potassium hydroxide) or pH Down (phosphoric acid).
EC (Electrical Conductivity) measures how many dissolved nutrients are in your solution, in millisiemens per centimeter (mS/cm). Higher EC = more nutrients. Seedlings and leafy greens typically run at EC 0.8–1.6; fruiting plants at EC 1.8–2.8.
PPM (Parts Per Million) is another way to express dissolved solids - often used in the US. EC 1.0 mS/cm converts to approximately 500–700 PPM depending on which conversion factor your meter uses. Many meters show both.
You don't need to memorize conversions at the start. Pick one unit (EC is more internationally standard) and use it consistently.
The five main hydroponic systems
Deep Water Culture (DWC): Plant roots hang into a reservoir of aerated nutrient solution. Simple, effective, excellent for beginners.
Nutrient Film Technique (NFT): A thin stream of solution flows continuously over roots in a tilted channel. Water-efficient at scale; slightly more failure risk if pump stops.
Kratky (passive DWC): No pump - roots sit above a static reservoir and a gradually descending water level creates an air gap for oxygen. Zero electricity for the water system. Best for single plants and low-maintenance growing.
Ebb and Flow (Flood and Drain): A tray of plants is periodically flooded with nutrient solution, then drained back to a reservoir. Flexible and scalable.
Aeroponics: Roots hang in air and are misted with nutrient solution at intervals. Most efficient oxygen delivery; most technically complex.
For beginners, DWC or Kratky are the right starting points. Both are forgiving, cheap to build or buy, and produce great results with herbs and leafy greens.
What you can realistically grow
Easy wins (beginner-recommended): Lettuce, basil, mint, chives, spinach, bok choy - all fast, forgiving, and productive in small systems.
Intermediate: Kale, cilantro, Swiss chard, strawberries - slightly more demanding in light or temperature requirements.
Advanced: Cherry tomatoes, peppers, cucumbers - require higher light intensity (400+ µmol/m²/s PPFD), more EC management, and physical support (trellising).
Start with leafy greens and herbs. You'll build the skills for everything else naturally.
This guide is reviewed against published horticultural research. It is not a substitute for advice from a certified horticulturalist or your local cooperative extension service.