What hydroponic weed is
Hydroponics means growing plants without soil, using water-based mineral nutrient solutions. The roots either sit in the liquid or are held up by an inert material such as perlite or gravel, as Wikipedia summarizes it, and the word comes from the Greek for water and labour, according to Oklahoma State University Extension. "Hydroponic weed" describes how a plant was grown, not a type of strain.
Is it stronger? A 2019 review in the American Journal of Plant Sciences found that, despite a common belief that hydroponic plants grow faster and yield more, the evidence shows no gain in yield or potency over soil. The same review says hydroponics gives more control and makes nutrient problems quicker to trace, while soil buffers mistakes better and is simpler to set up.
The main hydroponic systems
The 2019 review splits systems into active ones that use pumps (ebb and flow, nutrient film technique, drip, aeroponics and deep water culture) and passive ones, such as wick systems, that move water to the roots by capillary action. Roots are usually anchored in rockwool, the most widely used medium, which starts out alkaline and needs conditioning, or in inert, pH-neutral clay pebbles (Wikipedia). The common systems for home growers:
- Deep water culture (DWC): each plant sits in a net pot in a lid, roots hanging into a tank of nutrient solution kept oxygenated by an air pump and air stone. University of Minnesota Extension calls it the most common, least expensive and easiest system for small-scale growers, and advises keeping only a third to a half of the roots submerged once they grow past the pot.
- Ebb and flow (flood and drain): a pump floods a tray of plants in growing medium from a separate reservoir, then the solution drains back (UMN Extension). Advanced Nutrients, a nutrient maker, notes that with no drip emitters there is less clogging, but moving large volumes of water raises the risk of leaks.
- Drip: solution runs through hoses with emitters at the base of each plant, often in bags of coco coir (UMN Extension). Advanced Nutrients warns that drip lines and emitters can clog with particles.
- Nutrient film technique (NFT): a very shallow stream of solution flows along sloped channels past bare roots and back to the reservoir. Roots get plenty of oxygen, but Wikipedia notes NFT has very little buffer if the flow stops, for example in a power outage.
- Coco coir, the hybrid: coir, a coconut husk byproduct, holds water well (UMN Extension) but supplies no nutrients, so Grow Weed Easy counts coco as a type of hydroponics and places the results between soil and a hydro reservoir.
Hydro vs soil: the trade-offs
- Control: you decide exactly what the roots get, and nutrient problems are quicker to trace (2019 review).
- Less buffering: soil holds nutrients and steadies pH; without it, pH, oxygen and nutrient levels change much faster in a hydroponic system (Wikipedia; Oklahoma State).
- More gear and upkeep: the review notes hydroponics needs a constant supply of water, electricity and nutrients, and UMN Extension warns that if a pump fails or the power goes out, plants can dry out quickly.
- Root disease can spread: in hydroponically grown cannabis, Punja and colleagues (2019) found Pythium and Fusarium root rots that browned roots and stunted and yellowed plants, and showed that Fusarium spores travel in nutrient solution.
- No proven yield or potency gain: see the review above; Grow Weed Easy even says soil-grown buds may smell stronger. If soil appeals more, living soil organic (LSO) growing is the opposite approach.
pH and EC basics
Two numbers run a hydroponic grow. pH (0 to 14, with 7 neutral) controls which nutrients roots can take up. Electrical conductivity (EC) measures dissolved fertilizer salts: too high causes osmotic stress and toxicity, too low leads to deficiencies (Oklahoma State). EC rises when you add nutrients and falls as plants use them, but it says nothing about any single nutrient (UMN Extension).
Published pH targets differ, so treat them as starting points:
- American Herbal Pharmacopoeia, cited in the 2019 review: 5.8 to 6.0 for hydroponics, 6.5 to 7.2 for soil. The review adds that the optimal pH and EC for cannabis have not yet been established by experiments.
- Oklahoma State Extension, for soilless crops in general: a solution pH of 5 to 6, usually 5.5, so the root zone stays around 6 to 6.5.
- Grow Weed Easy: 5.5 to 6.5 for coco and hydro, versus 6 to 7 for soil.
- Royal Queen Seeds: 5.5 to 5.8, with about 6 preferred in flowering.
Keeping pH and EC in range
There is little cannabis research on EC. In a coir study summarized in the 2019 review, yields fell at the two highest feeding rates, when EC reached about 3.0 and 3.8 mS/cm.
Oklahoma State's routine for hydroponic crops: calibrate both meters with buffer solutions, set EC first and then pH, check both daily at the same time of day, and replace the whole solution every 2 weeks. Royal Queen Seeds suggests weekly changes for cannabis.
Common beginner mistakes
- Overfeeding. Beyond the osmotic stress described above, overfertilizing feeds algae on roots (UMN Extension).
- Drowning the roots. Fully immersed roots cannot get oxygen and can rot (UMN Extension).
- Letting the reservoir warm up. Cold water holds more dissolved oxygen than warm water (USGS), and Royal Queen Seeds suggests about 20°C for cannabis.
- Letting light in. Reservoirs and channels should block light to stop algae and fungal growth (Wikipedia; UMN Extension).
- Organic nutrients in a reservoir. The 2019 review says they ferment, causing contamination and clogging.
- Dirty equipment. Clean and sanitize containers and tools between plantings (UMN Extension); Punja's team found root pathogens moving through recirculated solution.
- Guessing at symptoms. If leaves curl, yellow or burn at the tips, check pH, feed strength and roots before changing anything else; what causes curling cannabis leaves goes through each cause.
Canada's home-grow limits
Under federal rules, adults can grow up to 4 cannabis plants per household, not per person, according to Health Canada. It also recommends a professional for any electrical changes, which matters for pumps and lights. For starting material, pick seeds from a seller you trust, and if you take a clone, ask how the mother plant was grown and what it was sprayed with.
- Ontario: up to 4 plants per residence if you are 19 or older, the plants are for personal use, and your lease or condo rules allow it (Government of Ontario).
- Quebec: growing or possessing cannabis plants for personal use is banned, and the Supreme Court of Canada upheld the ban on April 14, 2023.
- Manitoba: since May 1, 2025, adults 19 and older may grow up to 4 plants per household, indoors and out of reach of young people (Government of Manitoba).
Ready to start, or not
For the full first grow, from seed to harvest, see growing a weed plant for beginners.
If daily reservoir checks are not for you, GasDank offers same-day delivery across Toronto and the GTA, usually within 1 to 2 hours, and mail order across Canada. The menu carries lab-tested products; browse all flower. Customers must be 19 or older (21 in Quebec), with ID checked at the door.
