annual
A plant that completes its life cycle—from germination through seed production—within one growing season.
chlorophyll
The green pigment that captures light energy for photosynthesis. Plants can make chlorophyll in light, but many tissues also form it after developing in darkness.
cross-pollination
Transfer of pollen from a flower on one plant to a flower on another plant of the same or a compatible species.
cultivar
A cultivated plant selected and maintained for particular traits. Its name is usually written in single quotation marks, such as zinnia ‘Envy’.
disbudding
Removing selected flower or fruit buds so a plant directs resources into fewer remaining ones.
florets
The small individual flowers that together make a larger flower cluster or head, such as a lilac cluster or sunflower centre.
hardy
Able to survive specified outdoor conditions, especially winter cold. Hardiness depends on the plant, location, drainage, exposure, and climate—not on general toughness.
heavy metals
A loosely used group of dense metallic elements. Some, such as lead and cadmium, can contaminate soil and harm people or plants at low concentrations; a laboratory test is needed to measure them.
hill
To draw soil up around a plant, as with potatoes; it can also mean a small planting mound or a group of seeds planted together.
hybrid
An offspring produced by crossing genetically different parents. Garden hybrids may be between cultivars, varieties, subspecies, or sometimes compatible species.
layering
Encouraging a stem to form roots while it remains attached to its parent plant, then separating it after a strong root system develops.
microclimate
The climate of a small place—such as a sheltered wall or low frost pocket—that differs from the surrounding area.
mineral oil
A refined petroleum-derived oil. Horticultural oils are specially formulated pesticide products; household mineral oil is not a substitute and any pesticide must be used by an adult exactly as labelled.
floral foam
A water-holding synthetic foam once common in flower arrangements. It is not compostable and can shed plastic particles, so this site favours reusable pin holders, grids, twigs, pebbles, or flower frogs.
peat moss
Partly decomposed sphagnum and other peatland plant material. It holds water and is acidic but is not a complete fertilizer; harvesting peat affects carbon-storing wetland habitat.
perennial
A plant that lives for more than two years. Some die back to the ground each winter; evergreen and woody perennials do not.
pesticides
Products intended to prevent, destroy, repel, attract, or control a pest. The term includes herbicides, insecticides, fungicides, rodenticides, and some other products—not only synthetic chemicals.
photosynthesis
The process by which plants, algae, and some microbes use light energy to make sugars from carbon dioxide and water, releasing oxygen.
propagate
To produce new plants by seed or by methods such as division, cuttings, grafting, tissue culture, or layering.
rooting hormone
A product containing a plant-growth regulator that can encourage roots on some cuttings. It is optional for many plants and must be handled according to its label.
rhizome
A horizontal stem, often underground, that has nodes and can produce both shoots and roots. Cannas and many irises grow from rhizomes.
seed pod
A dry fruit that contains seeds. Botanically, not every seed-holding fruit is a pod.
silica gel
A porous form of silicon dioxide used to absorb moisture. Only a product sold and labelled for the intended craft or storage use should be handled; packets marked “do not eat” are not toys.
stake
A post used to support or mark a plant. Ties should be broad and loose enough not to cut into a growing stem.
star florets
An informal description for individual flowers whose spreading lobes create a star-like outline.
sucker
A shoot arising from a root or from the lower stem. It may renew a shrub, spread a plant, or come from a graft's rootstock.
thinning
Removing selected seedlings, shoots, flowers, or fruits to reduce crowding or direct a plant's resources.
true leaves
Leaves produced after the seed leaves, or cotyledons. They usually begin to show the characteristic shape of the mature plant.
tuber
An enlarged storage organ. A potato is a stem tuber with buds called eyes; a dahlia has tuberous roots and its buds remain on the crown.
vermiculite
A heat-expanded mineral used in potting mixes to hold water and nutrients while keeping pore space. Use horticultural-grade material and avoid making dust.
wick
An absorbent strip that moves water through tiny spaces by capillary action, often from a reservoir into drier potting mix.
hardiness zone
A mapped estimate of regional climate used mainly to judge whether perennial plants may survive winter. Canada's system combines several climate variables and is not interchangeable with every other country's zone map.