ACID-MEDIUM — A compost which contains little or no lime and has a pH of less than 6.5. Sometimes referred to as “sour” soil by gardeners.
AERATION — The loosening of soil by digging or other mechanical means to allow air to pass freely.
AERIAL ROOT — A root which grows out from the stem above ground level. Aerial roots are commonly seen on mature specimens of Monstera deliciosa
AEROBIC — Usually used for describing a characteristic of compost heaps. Describes organisms living or occurring only in the presence of oxygen.
AIR-LAYERING — A method of propagating single-stem plants, such as Ficus elastica decora, which have lost their lower leaves and become leggy. An incision is made to a portion of outer stem layer, damp sphagnum moss is wrapped in a bag around it until roots develop. Then it is cut and replanted with its shorter stem size.
ALKALINE SOIL — Soil that has a pH level of about 7.0 or more. Sometimes referred to as “sweet” soil by gardeners.
ALTERNATE — Leaf form, where the leaves are arranged singly at different heights on the stem. Compare opposite and whorled.
ANAEROBIC — Describes organisms living or occurring when oxygen is absent. Usually term used when talking about compost heaps.
ANNUAL — A plant which completes its life cycle within one year of germination. Compare biennial and perennial.
ANTHER — The part of the flower which produces pollen. It is the upper section of the stamen.
APICAL — At the tip of a branch.
AQUATIC — Plant which grows partially or completely in water.
AREOLE — A small well-defined area, usually hairy and cushion-like, found on the stem of cacti. From them arise spines or glochids.
ASEXUAL — Vegetative reproductions – e.r. cuttings and division.
AWL-SHAPED — A narrow leaf which tapers to a stiff point.
AXIL — The angle between the upper surface of a leaf or leaf stalk and the stem that carries it. A growth or flower bud (axillary bud) often appears in the axil.
BARE-ROOT — Usually referring to decidious shrubs and trees, and some other perennials, with all the soil removed from their roots that are sold at nurseries.
BEARDED — A petal bearing a tuft or row of long hairs.
BEDDING PLANT — Plants suitable for massing in beds for their colourful flowers or foliage. Usually annuals.
BICOLOR — A flower with petals which bear two distinctly different colours. BIENNIAL — A plant which completes its life cycle in two seasons. Compare annual and perennial.
BI-GENERIC — A hybrid produced by crossing two different genera.
BIOLOGICAL PEST CONTROL — Using living organisms such as beneficial insects or parasites to destroy garden pests.
BLADE — The expanded part of a leaf or petal.
BLEEDING — The loss of sap from plant tissues which have been cut.
BLIND — The loss of the growing point, resulting in stoppage of growth. Also, failure to produce flowers or fruit.
BLOOM — A natural mealy or waxy coating covering the leaves of some house plants.
BOLT — Annual vegetables or flowers that grow quickly to flowering stage at the expense of their best overall development.
BONSAI — The art of dwarfing trees by careful root and stem pruning coupled with root restriction.
BOSS — A ring of prominent and decorative stamens.
BOTANICAL NAME — The Latin scientific name of a plant is its botanical name. There is only one botanical name per plant so if you want a specific variety, use it’s botanical name to be sure you’re getting what you want.
BOTTLE GARDEN — A form of terrarium in which a large and heavy glass container such as a carboy is used.
BOTTOM HEAT — Under-surface heat provided in the soil by electric cables or hot water pipes.
BRACT — A modified leaf, often highly coloured and sometimes mistaken for a petal. Examples of house plants with showy bracts are poinsettia, aphelandra and bougainvillea.
BREAK — Production of a side shoot after removal of the growing point.
BULB — A storage organ, usually formed below ground level, used for propagation. A true bulb consists of fleshy scales surrounding the central bud, but the term is often loosely applied to corms, rhizomes and tubers.
BULBIL — An immature small bulb formed on the stem of a plant.
BULBLET — An immature small bulb formed at the base of a mature bulb; e.g hyacinth.
CALCITIC LIMESTONE — A common material used for ‘liming’ soil that has an acid level that is too high. This type is most commonly used and contains calcium carbonate.
CALICHE — A soil condition found in some areas of the arid Southwest U.S., or as the result of synthetic fertilisers, caliche is a deposit of calcium carbonate (lime) beneath the soil surface. This condition is more commonly called ‘hardpan’ and creates an impervious layer in lower levels of soil.
CALYX — The outer ring of flower parts, usually green but sometimes coloured.
CAPILLARY ACTION — The natural upward movement of water in confined areas, such as the spaces between soil particles.
CARBOY — A large and heavy glass vessel, originally designed for the storage of chemicals but now commonly used as a container for bottle gardens.
CARNIVOROUS — Used in the gardening world to denote a plant (usually tropical) that typically lives in highly acidic soil that does not provide enough nourishment. Nature has adapted these plants to trap and consume insects. An example is the Venus Flytrap plant.
CHLOROSIS — An abnormal yellowing or blanching of the leaves due to lack of chlorophyll.
CLADODE — A modified stem which has taken on the form of a leaf; example: the thin “leaves” of asparagus fern.
COLOURED LEAF — Leaves with one or more colors apart from green, white or cream are distinctly present.
COMPOST — a potting or seed/cutting mixture made from peat (soil-less compost) or sterilised soil (loam compost) plus other materials such as sand, lime and fertilizer. Compost is also a term for decomposed organic matter such is what’s left after a compost heap has degraded vegetable and animal matter. An excellent source of organic material for rebuilding and enriching soil.
COMPOST HEAP / COMPOSTING — The result and act of combining organic materials under controlled conditions so that the original raw ingredients are transformed by decay and degradation into humus (or compost).
COMPOUND FLOWER — A flower made up of many florets, e.g. chrysanthemum.
COMPOUND LEAF — A leaf made up or two or more leaflets attached to the leaf stalk; e.g. Schefflera.
CONSERVATORY — A structure composed partly or entirely of glass, perhaps attached to the house and within which a large number of plants are grown and enjoyed.
CORM — A swollen, underground stem base used for propagation.
COROLLA — The ring of separate or fused petals which is nearly always responsible for the main floral display.
COVER CROP — A crop grown to protect and enrich the soil or to control weeds.
CRESTED, or CRISTATE– Cockscomb-like growth of leaves, stems or flowers.
CROCKERY, CROCK or POT-SHARD — A piece of broken pot used to help drainage. Almost always referring to clay or ceramic pieces.
CROWN — The region where shoot and root join, usually at or very near ground level.
CULTIVAR — Used when determining plant names. Indicates the variety originated in cultivation, as opposed to in the wild. This portion of a plant’s name is usually not Latin.
CUTTING — A piece of a plant (leaf, stem or root) which can be used to produce a new plant.
CYME — A flat-topped or domed flower head in which the flowers at the center open first.
DAMPING OFF — Decay of young seedlings at ground level following fungal attack, but also is the result of soil-borne diseases and over-watering.
DEAD-HEADING — The removal of faded heads of flowers.
DECAY-CYCLE — The changes that occur as plants grow, die, and break down in the soil.
DECIDUOUS — These are plants that loose their leaves at the end of the growing season. Maple trees are a good example.
DIOCECIOUS — A plant which bears either male or female flowers. (Compare to monoecious.)
DISC (DISK) — The flat central part of a compound flower. It is made up of short, tubular florets.
DISTILLED WATER — Pure water free from dissolved salts. Formerly made by distillation, now produced chemically by demineralisation.
DIVISION — A method of propagating plants by separating each one into two or more sections and then re-potting.
DOLOMITIC LIMESTONE — Sometimes used when ‘liming’ soil that has an acid pH level that is too high. As it contains calcium and magnesium carbonate it should be used only with soils that are also deficient in magnesium as well. (See also Calcitic Limestone)
DORMANT PERIOD (DORMANCY) — The time when a plant has naturally stopped growing and the leaves have fallen or the top growth has died down. The dormant period is usually, but not always, in winter. Compare resting period.
DOUBLE FLOWER — The Latin name for this is “flore pleno.” It refers to flowers that have many petals present, such as roses.
DOUBLE POTTING — An American term for placing a potted plant in a larger pot with damp peat moss surrounding it. The peat is kept moist and provides a humid evaporative effect for the potted plant nestled between it.
DRAWN — Excessively tall and weak growth, caused by plants being grown in too little light or too closely together.
ENTIRE LEAF — An undivided and un-serrated leaf.
EPIPHYTE — A plant which grows above ground attaching itself to trees or rocks. The Amazon Air Plant seen in many nurseries is a good example.
EVAPOTRANSPIRATION — Abbreviated as E.T., it is the amount of water that transpires through a plants leaves combined with the amount that evaporates from the soil in which it is growing. Used as a guide for how much water a plant needs per day/week/year.
EVERGREEN — A plant which retains its leaves in a living state during the winter.
EVERLASTING — Flowers with papery petals which retain some or all of their color when dried for winter decorations.
EXOTIC — Strictly speaking, a plant which is not native to the area, but popularly any unusual or striking plant.
EYE — Two unrelated meanings — an undeveloped growth bud or the center of a flower.
F1 HYBRID — A first generation offspring of two purebred strains. An Fl hybrid is generally more vigorous than an ordinary hybrid.
FAMILY — One genus or several genera which have a basically similar floral pattern make up a family.
FERTILIZING/FERTILIZER — The act of or the actual substance added to soil to provide additional nutrients for plants. May also be used to describe the pollination process flowers undergo with the help of bees and other insects.
FIBROUS-ROOTED — A root system which contains many thin roots rather than a single tap root.
FLAT — A shallow box or tray used to start cuttings or seedlings.
FLORET — A small flower which is part of a much larger compound flower head; e.g Cineraria.
FLOWER SPIKE — A flower head made up of a central stem with the flowers growing directly on it.
FOLIAR FERTILIZER — A fertilizer applied in liquid form to a plant’s foliage in a fine spray so that the plant can absorb the nutrients through its leaves.
FORCING — The process of making a plant grow or flower before its natural season.
FROND — A leaf of a fern or palm, which usually constitutes a whole branch.
FUNGICIDE — A chemical used to control diseases caused by fungi (the plural form of “fungus.”
FUNGUS — A primitive form of plant life which is known to the house plant grower as the most common cause of infectious disease — powdery mildew. sooty mould and area mould.
GENUS — Used when naming plants. Genus is the plant equivalent of our surnames. When followed by the name of the ‘Species’ you have its botanical name. The genus is almost always in Latin.
GERMINATION — The first stage in the development of a plant from seed; a seed has germinated when it is broken open and begins to grow a sprout.
GIRDLING — The choking of a branch by a wire, rope or other inflexible material which usually occurs most often in woody stemmed plants that have been tied down too tightly without regard for growth.
GLABROUS — Plant surface which is smooth and hairless.
GLAUCOUS — Plant surface which is covered with a bluish-grey bloom.
GLOCHID — A small hooked hair borne on some cacti.
GRAFTING — The process of joining a stem or bud of one plant on to the stem of another.
GREEN MANURE — A crop (such as rye grass) that is grown and then incorporated into the soil to increase soil fertility or organic matter content. Usually turned over into the soil a few weeks before new planting begins.
GROUND COVER — A plant used to provide a low-growing carpet between other plants.
GROWING POINT — The tip of a stem, which is responsible for extension growth.
HALF-HARDY — An indoor plant that requires a minimum temperature of 50″-55″F for healthy growth, as opposed to the “tender” plants.
HARDENING OFF — Gradual acclimatization to colder conditions. Usually used when talking about transplanting of greenhouse plants or seedlings. Can be as simple as moving outside into a protected area for a short time, or made more complicated.
HARDY — A plant which can withstand prolonged exposure to temperatures at or below 45″F. Compare this to the ”half-hardy” and “tender” qualities of other plants.
HEEL — A strip of bark and wood remaining at the base of a side shoot cutting pulled off a main shoot. Some cuttings root more readily if a heel is attached.
HERB — A plant grown for flavouring, essential oils, cooking, or medicinal reasons. Lavender is an herb, and is used for all those purposes.
HERBACEOUS — A plant with a non-woody stem.
HONEYDEW — Sticky, sugary secretion deposited on plants by insects such as aphid and whitefly. Honeydew is also a variety of sweet melon.
HOUSE PLANTS — Plants that are grown and raised indoors in containers.
HUMIDIFIER — A piece of equipment used to raise the humidity of the air in a room.
HUMUS — A dark coloured, stable form of organic matter that remains after most of plant or animal residues have decomposed.
HYBRID — A plant with parents which are genetically distinct. The parent plants may be different cultivars, varieties, species or genera but not different families.
HYDROPONICS — A method of growing a plant in water containing dissolved nutrients.
HYGROMETER — An instrument used to measure the relative humidity of the air. INFLORESCENCE — The arrangement of flowers on the stem. A flower head.
INOCULANTS — A seed treatment medium that contains the sybiotic rhizobial bacteria to capture nitrogen when in contact with legume roots.
INORGANIC — A chemical or fertilizer which is not obtained from a source which is or has been alive.
INSECTICIDE — A chemical (synthetic or organic) used to kill or repel insects.
INTERNODE – The part of the stem between one node and another.
KNOCKING-OUT — The temporary removal of a plant from its pot in order to check the condition of the root ball.
KEEL — A boat-shaped structure formed by the two lower petals of many members of the Leguminosae.
LATEX — Milky sap which exudes from cut surfaces of a few house plants, such as Ficus elastica decora and Euphorbia.
LEACHING — A similar concept to making tea which leaches out the flavour of the tea leaves. This concept regards how water will rinse bad substances (like salt) or good ones (like nutrients) down deep into the soil or as run-off.
LEAF MOULD — Partially decayed leaves used in some potting mixtures. It must be sieved and sterilized before use.
LEAFLET — A leaf-like section of a compound leaf.
LEGGY — Abnormally tall and spindly growth.
LEGUME — A plant whose roots form an association with soil-borne bacteria that can capture atmospheric nitrogen. A good example of this are soybeans.
LOAM — Good quality soil used in preparing compost. Adequate supplies of clay, sand and fibre must be present.
LONG DAY PLANT — A plant which requires light for a longer period than it would normally receive from daylight in order to induce flowering; e.g Saintpaulia.
MANURE — An organic material excreted by animals (usually from steer is sold commonly) this is used as a fertilizer and an amendment to enrich the soil.
MICROCLIMATE — The warmth and humidity of the air in close proximity to a plant. It may differ significantly from the general climate of the room.
MICROCUTTING — A plant produced by micropropagation — a modern technique using tiny pieces of the parent plant on a sterile nutrient jelly.
MICRO-ORGANISMS — Animals and plants that are too small to be seen clearly with the naked eye.
MIST PROPAGATION — The ideal method of propagation under glass, using automatic mist generators and soil heaters.
MONOECIOUS — A plant which bears both male and female flowers. (Compare to dioecious)
MOUTH — The open end of a bell shaped or tubular flower.
MULCH — Any loose, usually organic material placed over the soil as a protective covering or for decorative purposes. Common mulches are ground bark, saw dust, leaves or straw. Stones or pebbles may also be used for mulching.
MULTI-COLOUR or MULTICOLOR — A flower with petals which bear at least three distinctly different colours. This new feature can be inherited.
MUTATION — A sudden change in the genetic make-up of a plant, leading to a new feature.
NEUTRAL — Neither acid nor alkaline; pH 6.5-7.5.
NITROGEN CYCLE — The transformation of nitrogen from an atmospheric gas to organic compounds in the soil, then to compounds in plants and eventually the release of nitrogen gas back into the atmosphere.
NITROGEN FIXATION — The capture and conversion of atmospheric nitrogen gas into nitrogen compounds, stored in the soil, that can be used by plants.
NODE — The point on a stem where a leaf or bud is attached.
OFFSET — A young plantlet which appears on a mature plant. An offset can generally be detached and used for propagation.
OPPOSITE — Leaf form, where the leaves are arranged in opposite pairs along the stem. Compare alternate.
ORGANIC — A chemical or fertilizer which is obtained from a source which is or has been alive. Also the general term used for a type of gardening using no chemical or synthetic fertilizers or pesticides.
OSMUNDA FIBRE (FIBER) — The roots of the fern Osmunda regalis, used for making Orchid Compost.
OVER-POTTING — Repotting a plant into a pot which is too large to allow successful establishment.
PALMATE LEAF — Five or more lobes arising from one point — hand-like.
PEAT (called peat moss in the U.S) — Partially decomposed sphagnum moss or sedge used in making composts. Valuable for its pronounced air- and water-holding capacity and its freedom from weeds and disease organisms.
PEBBLE-TRAY — Grouping potted plants within a shallow, pebble filled tray in order to maintain humidity in an environment with central heating. Water is poured into the pebbles and evaporates up and around the plants.
PEDICEL — The stalk of an individual flower.
PEDUNCLE — The stalk of an flower head. (see also Inflorescence)
PENDANT — Hanging.
PERENNIAL — A plant which will live for three years or more under normal conditions.
PERFOLIATE — Paired leaves which fuse around the stem.
PERLITE — A mineral expanded by heating to form very lightweight, porous white granules useful in container soil mixes to enhance moisture and air retention.
PETAL — One of the divisions of the corolla — generally the showy part of the flower.
PETIOLE — A leaf stalk. pH — A measure of acidity and alkalinity. Below pH 6.5 is acid, above pH 7.5 is alkaline.
PHYLLODE — A leaf stalk expanded to look like and act like a leaf.
PICOTEE — Term applied to a narrow band of color on a pale ground at the edge of a petal. PINCHING-OUT — The removal of the growing point of a stem to induce bushiness or to encourage flowering. Also known as stopping.
PINNATE LEAF — A series of leaflets arranged on either side of a central stalk.
PIP — This term has two distinct meanings — the seed of some fruits (e.g orange) and the rootstock of some flowering plants (e.g convallaria).
PISTIL — The female reproductive parts of the flower.
PLANT WINDOW — Double window with plants grown in the space between.
PLUG — A small but well-rooted seedling raised in a cellular tray and sold for growing.
PLUNGING — The placing of a pot up to its rim outdoors in soil, peat or ashes.
POLLEN — The yellow dust produced by the anthers. It is the male element which fertilised the ovule.
POT-BOUND — A plant growing in a pot which is too small to allow proper leaf and stem growth.
POTTING-ON — The re-potting of a plant into a proper-sized larger pot which will allow continued root development.
PRICKING-OUT — The moving of seedlings from the tray or pot in which they were sown to other receptacles where they can be spaced out individually.
PROPAGATION — In gardening usage, this refers to the many different ways of starting new plants.
PRUNING — A method of cutting off leaves or branches within limits in order to remove dead or diseased foliage or branches. Also used to control or direct growth, increase quality or yield of flowers or fruit and to ensure growth position of main branches to enhance structural strength.
RESTING PERIOD — The time when a plant has naturally stopped growing but when there is little or no leaf fall. Compare with the dormant period.
RETICULATE — Marked with a branched network of veins or fibres.
RHIZOME — A thickened stem which grows horizontally below or on the soil surface.
ROOT BALL — Matted roots plus enclosed soil within a the pot of a container grown plant.
ROOTING HORMONE — A chemical in powder or liquid form which promotes the formation of roots at the base of a cutting.
ROSETTE — Term applied to a whorl of leaves arising at the base of a plant.
ROW COVERS — Several types of semitransparent materials used to cover plants, trapping heat, enhancing growth, and provide protection from frost or winds.
RUGOSE — Rough and wrinkled.
RUNNER — A creeping stem which produces small plantlets along its length. Sometimes called a ‘Stolen.’
SELF-COLOUR — A flower with single coloured petals.
SEPAL — One of the divisions of the calyx.
SERRATE — Saw-edged leaf design. SESSILE — A stalk-less leaf or flower which is borne
directly on the stem.
SHEET COMPOSTING — A method of spreading un-decomposed organic materials over the soil’s surface, then working them into the soil to decompose, rather than piling them and spreading the resulting compost.
SHORT DAY PLANT — A plant which requires light for a shorter period than it would normally receive from daylight in order to induce flowering; e.g Chrysanthemum and Poinsettia.
SHRUB — A woody plant with a framework of branches and little or no central stem. Compare it to the tree.
SINGLE FLOWER — A flower with a normal amount of petals present, arranged in a single row. Daisies are a good example of this type.
SOIL POLYMERS — Super absorbent polymers recently developed that can increase water retention of soils. They can absorb hundreds of time their weight in water and are primarily used in container bound plants.
SPADIX — A fleshy flower spike in which tiny florets are embedded.
SPATHE — A large bract, sometimes highly coloured, surrounding or enclosing a spadix. The spathe flower is characteristic of the aroids, such as Anthurium and Spathiphyllum.
SPECIES — Used when naming plants. Designates a specific species of the ‘Genus’ and is best described as the plant worlds equivalent to our Christian names (or first names). Will follow the Genus name and is usually in Latin. Note: Once a plants full name is used, i.e. Hedera helix, future listings will abbreviate the Genus name and follow it with the species name. An example would be “H. helix”, as the next plant in a listing.
SPHAGNUM MOSS — Various mosses native to bogs are sphagnum. Often used for the lining of hanging baskets and for air layering.
SPORE — A reproductive cell of non-flowering plants, such as ferns.
SPORT — A plant which shows a marked and inheritable change from its parent; a mutation.
STAMEN — The male reproductive parts of a flower.
STANDARD — A plant which does not normally grow as a tree but is trained into a tree-like form.
STERILISED (sterilized) SOIL — A rather misleading term, as steam- or chemically sterilised soil is only partially sterilised. Harmful organisms which were in it have been killed, but some bacteria remain.
STIGMA — The part of the female organ of the flower which catches the pollen.
STIPULE — A small outgrowth at the base of the leaf stalk.
STOLON — See “Runner”.
STOPPING — See pinching out.
STOVE PLANT — A plant which requires warm greenhouse conditions in winter.
STRAIN — A selection of a variety, cultivar or species which is raised from seed.
SUCCULENT — Succulents plants have leaves and/or stems which are thick and fleshy. They often have waxy outer layers that allow the plants to retain water well.
SUCKER — A shoot which arises from an underground shoot or root of a plant, for example a rose bush.
SYSTEMIC — A pesticide which goes inside the plant and travels in the sap stream.
TAP ROOT — A strong root, sometimes swollen, which grows vertically into the soil or compost.
TENDER — An indoor plant which requires a minimum temperature of 60″F. Occasional short exposure to temperatures below this level may be tolerated. Compare hardy and half hardy.
TENDRIL — A thread-like stem or leaf which clings to any nearby support.
TERMINAL — The uppermost bud or flower on a stem.
TERRARIUM — A partly or entirely closed glass container used to house a collection of indoor plants.
TERRESTRIAL — Describes a plant which grows in the soil.
TOPIARY — The art of clipping and training woody plants to form geometric shapes or intricate patterns. Box and Myrtle are suitable types.
TOPDRESS — A process that means to apply on the surface of soil. Usually referring to the spreading of organic material such as ground bark or manure.
TRANSPIRATION — The loss of water through the pores of the leaf.
TREE — A woody plant with a distinct central trunk. Compare to the shrub.
TUBER — A storage organ used for propagation. It may be a fleshy root (e.g dahlia) or a swollen underground stem.
UMBEL — A part of the plant bearing flowers in which all the flower stalks are of similar length and arise from the same point.
UNISEXUAL — A flower of one sex only.
VARIEGATED LEAF — A green leaf design which is blotched, edged or spotted with yellow, white or cream colour.
VARIETY — One of possibly many closely-related plant species. The variety name is usually in Latin.
VERMICULITE — This is a mineral called mica that is heated and puffed up to form lightweight, sponge-like granules capable of holding both water and air.
WEED — An uninvited and usually unattractive plant that surfaces in gardens. Usually seeds are delivered by winds, but not always. Sometimes referred to as a “volunteer” plant.
WHORLED — Leaf form, where three or more leaves radiate from a single node.
XERISCAPE — A patented name (invented by the Denver Water Department) that stands for water-conserving landscapes.
XEROPHYTE — A plant which is able to live under very dry conditions.