Glossary of Gardening

Glossary of Gardening Terms: I to P

We realise it can get a little confusing sometimes trying to decipher grow guide instructions, botanical research papers and other publications relying heavily on horticultural terminology, so here’s the third part of our guide to the botanical basics, with our A-Z glossary of gardening terms.

An A-Z Glossary of Gardening: A to C | D to H | I to P | Q to Z


An A-Z Glossary of Gardening: I to P

Gardening Glossary – I

Inbred – Referring to the offspring produced by plants of the same ancestry or breed.

Inert – Being chemically non-reactive, thereby simplifying the control of a nutrient solution.

Integrated Pest Management (IPM) – A multi-faceted strategy for ecological pest management using several complementary methods. these can include natural parasites and predators, pest-resistant plant varieties, cultural practices, biological controls, physical techniques and (as a last resort only) pesticides.

Gardening Glossary – L

Lacewing – A beneficial insect which eats aphids.

Leach – To dissolve or wash away soluble soluble components using heavy watering.

Leaf curl – A malformation caused by various factors, including a lack of magnesium, too much fertiliser, over-watering, fungus and insects.

Leaflet – A small immature leaf.

Leaves – External plant foliage which contains light energy-converting chloroplasts and chlorophyll. Leaves grow from branches and stems.

Leggy – A condition caused by a lack of the blue light spectrum, too much nitrogen or a lack of CO2, resulting in unusually tall, sparsely-foliated plants.

Life cycle – The series of distinct growth stages through which a plant passes in its natural lifetime; e.g. seed, seedling, vegetative and floral.

Lime – Dolomite or hydrated lime can be used to both raise and stabilise a soil’s pH level.

Litmus paper – Chemically-treated paper manufactured for testing pH.

Loam – A crumbly organic soil comprising clay, sand and silt.

Gardening Glossary – M

Macro-nutrient – Referring to either one or all of the primary nutrients nitrogen, phosphorous and potassium, or else the secondary nutrients calcium and magnesium.

Medium – The growing medium – or mix – in which plants are grown.

Meristem – The apex of a plant’s growth.

Micro-nutrient – Also known as ‘trace elements’, small quantities of these are involved in all plant cellular and metabolic functions and include boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn).

Moisture meter – An electronic device used to measure the exact moisture content of soil at any specific point.

Mulch – Organic material (such as compost, grass clippings, leaves, straw or wood chips) spread over the earth’s surface to hold in moisture and help control weeds around plants.

Gardening Glossary – N

Nanometre – A unit of measurement used to measure the wavelength of light. 1 nanometre (nm) is 0.000000001 metres.

Necrosis – The localised death of part of a plant’s tissue.

No-Till-Gardening – A gardening technique which calls for no tilling of the soil subsequent to the first. Instead, mulches are regularly added, saving on labour and (ideally) reducing the occurrence of weeds.

N-P-K – An abbreviation for the three main essential plant nutrients, nitrogen (N), phosphorus (P) and potassium (K). This labelling format is commonly found on commercial fertiliser packaging.

Gardening Glossary – O

Organic matter – Composts or other material derived from plant material.

Organic – Scientifically, referring to carbon-based matter derived from living organisms; horticulturally, to describe the practice of gardening without the use of chemical or other synthetic fertiliser or pesticide.

Ovule – The egg located within a plant’s calyx. containing all of the female genes, fertilised ovules eventually become seeds.

Oxygen – A colourless and tasteless element required to sustain animal life and (in soil) to sustain plant life.

Gardening Glossary – P

Parasite – An organism that uses another host as it’s habitat (e.g. fungus).

Peat – Partially-decomposed moss and/or other vegetation.

Perennial – Any plant species which normally lives for three years or more (an annual lives for a year, a biennial for two). May be evergreen or else die back and return in the following season.

pH: A scale running from 0-14 used to measure the degree of acidity or alkalinity of a substance. Horticulturally important due to its effects on nutrient availability and soil microorganisms.

pH tester – An electronic device or chemical substance used to measure pH levels.

Photo-period – The relationship between the proportion of light to dark within a twenty-four hour period.

Photosynthesis – The manufacture of carbohydrates from carbon dioxide, light energy and water.

Phototropism – The movement of part of a plant toward a source of light.

Pollen – Fine, dust-like micro-spores which contain male genes.

Primary nutrients – Referring to the essential plant nutrients; nitrogen, phosphorus and potassium (N-P-K). One of several gardening terms used to describe the same compounds.

Propagate – Asexual propagation is the production of seed via the breeding of distinct male and female flowers. Sexual propagation is the production of a new plant via cuttings taken from a mother plant.

Pruning – Altering a plant’s growth habit and general shape by the cutting of shoots and stems.

PVC pipe – Easily-worked, polyvinyl chloride plastic piping popularly used to bring water into a growroom.

Pyrethrum – A natural organic insecticide manufactured from chrysanthemum blossoms.


An A-Z Glossary of Gardening: A to C | D to H | I to P | Q to Z