Talk The Talk: Brush up on Your Hydroponic Vocabulary

Talk The Talk: Brush up on Your Hydroponic Vocabulary

Whatever the activity, there are two types of people: the kind who know the right lingo and the kind who don’t. Just ask the so-called baseball fan who talks about a game going into overtime instead of extra innings. Don’t be that person. For hydroponic growing, you can be in the know. This list of common terms makes it easy. 


Biosolids: The sewage removed during wastewater treatment that is sometimes sold as fertilizer.

Branch training: Tying or otherwise guiding the stems and limbs of plants to grow in directions that allow light to reach more of the plant.

Bud cycle: The period of a plants’ life when it is flowering. For some plants, the bud cycle occurs when plants get equal amounts of light and dark, or 12 hours on and 12 hours off; this is sometimes abbreviated as the 12/12 cycle.

Chlorosis: The yellowing of leaves caused by a nutrient deficiency or poor absorption of nutrients.

Cloning: Growing new plants from cuttings (see below) or other pieces of mature plants. The technical term is vegetative (or asexual) propagation. Many growers start with clones instead of seeds because clones are genetically identical to the parent plants, so they will have all the same characteristics.

Closed system: A hydroponic system in which the nutrient solution is continually recycled. Nutrient film technique setups are the most common example.

Colas: The nodes (or meeting points of bigger limbs) where flower buds form.

Coir: The fiber from the outer husk of coconuts, which can be used as a growing medium for hydroponic plants.

Cutting: A piece of leaf and stem that’s been snipped from a mature plant to be replanted and grown into a clone.

Damping off: A fungal disease that afflicts seedlings and kills them overnight, often with no prior sign of a problem.

Deep-water culture: A hydroponic system in which plants roots constantly hang in a solution of nutrient-rich, oxygenated water.

Ebb and flow: A hydroponic system in which plants’ roots are flooded with a nutrient solution at regular intervals and then drained. Also known as a flood and drain.

Feminized seeds: Growers who want to harvest unpollinated flower buds plant feminized seeds, which have no male chromosomes and therefore never produce pollen.

Flushing: Giving hydroponic plants only water (rather than a nutrient solution) can wash out excess or imbalanced nutrients. Flushing is a smart strategy whenever plants are ailing.

Foliar feeding: Fertilizing plants by spraying a nutrient solution on the leaves rather than feeding them through their roots. This works most effectively with fish-based organic fertilizers.

Germination: The period after planting when a seed first grows a stem and then a couple pairs of leaves.

Grow room: An area inside a home used for an indoor garden. It’s usually sealed off from outside light but ideally is well ventilated.

Growing medium: The various materials that hydroponic growers use to support plants’ stems, including clay pebbles, coir, vermiculite, or rock wool.

Insecticidal soap: Specially formulated fatty acids that cause many pests to dehydrate when they are sprayed with it.

Integrated pest management (IPM): The practice of eliminating insect problems with the least harmful solution, which is often organic, but not strictly.

Leachate: The fluids that drain out after a nutrient solution passes through plants’ roots.

Lollipopping: Cutting off the lower third of plants’ leaves and branches so that all the energy goes into the remaining leaves. The plant is then shaped like a lollipop.

Macronutrients: The major elements that plants must have in large amounts, specifically nitrogen, phosphorus, potassium, calcium, and magnesium.

Micronutrients: Essential minerals that plants need in minute amounts (less than 1 part per million), including copper, iron, and zinc. Sometimes called trace elements.

Mycorrhizae: Soil-dwelling fungi that help plants’ roots take up nutrients from organic fertilizers.

Necrosis: Leaves turning brown and dying caused by insufficient or imbalanced nutrients.

Neem oil: An oil pressed from the seeds of the neem tree (Azadirachta indica), an evergreen tree native to India, that is a highly effective insecticide and fungicide but is no danger to people or pets.

N-P-K ratio: On the label of every package of fertilizer, you’ll see the ratio of the primary nutrients nitrogen (N), phosphorus (P), and potassium (K), so you can choose the right nutrients for each stage your plants’ life cycle.

Nute burn: A condition that occurs when plants are overfed with fertilizer; it is often first noticeable in yellow leaf tips.

Nutes: Slang for liquid fertilizer or nutrients.

Nutrient solution: The blend of fertilizer and water that indoor gardeners use to feed and hydrate their crops.

Parts per million (PPM): The relative concentration of individual nutrients in a nutrient solution. PPM readings are important in letting you know whether you are fertilizing plants properly.

Pathogens: Any organisms—such as bacteria, viruses, or fungi—that cause plant diseases.

PH: A scale that measures the relative acidity or alkalinity of a solution. The scale is 0 (most acidic) to 14 (most alkaline), with 7 as neutral. The pH can have a dramatic effect on plants’ ability to absorb nutrients.

Photoperiod: The amount of time a plant is exposed to light, which is often tightly controlled by growers who want plants to flower indoors. For instance, plants that get 18 hours of light each day continue growing new leaves. When the photoperiod is changed to 12 hours of light followed by 12 hours of darkness, flowering plants begin their bud cycle.

Pyrethrin: A compound found in chrysanthemums that is a natural, nontoxic insecticide.

Reservoir: Where the fluid is stored in a hydroponic system that pumps a nutrient solution to plants, such as an ebb-and-flow system.

Rock wool: A popular growing medium for hydroponic growers. It is made from melting rock and extruding it into threads that are pressed into woven cubes.

Strain: Plants of the same species with unique characteristics (vigor, aroma, flavor, etc.) that are reproduced from one generation to the next.

Total dissolved solids (TDS): A measure of the concentration of elements in a nutrient solution. Measuring TDS helps you be sure that you’re giving your plants sufficient but not excessive nutrients.