Glossary

Garden words, in plain English.

The terms you'll meet in the pest guide, disease library, and lessons.

Pests

Beneficial insect: An insect that eats or parasitizes pests, like lady beetles, lacewings, and parasitic wasps. Avoid spraying where they are working, including neem and oils.
Btk: Bacillus thuringiensis var. kurstaki, a bacterium that only harms caterpillars that eat treated leaves. Sold under several brand names; any labeled Btk product works the same way.
Floating row cover: A light fabric laid over crops or on hoops. Light, air, and water pass through, but egg-laying insects can't reach the plants. Remove it at flowering for crops that need bees.
Frass: Insect droppings. Small dark pellets or sawdust-like crumbs on leaves or at a hole usually mean a caterpillar or borer is feeding nearby.
Honeydew: Sticky, sugary liquid left by sap-feeding insects such as aphids and whiteflies. Black sooty mold often grows on it.
Instar: One growth stage of a young insect between molts. Many caterpillars pass through four to six instars, getting bigger and hungrier at each one.
IPM (integrated pest management): Watch first, identify the pest, then use the gentlest fix that works: barriers, handpicking, and helpers before sprays.
Larva (larvae): The young, worm-like stage of insects such as beetles, moths, and flies. Caterpillars, grubs, and maggots are all larvae.
Mummy (aphid): A swollen, tan or bronze aphid with a tiny parasitic wasp growing inside. Leave mummies alone; they hatch into more helpers.
Nymph: The young stage of insects like aphids, squash bugs, and leafhoppers. Nymphs look like small, wingless versions of the adult.
Pupa: The resting stage between larva and adult, often in the soil or a cocoon.
Trap crop: A plant grown to draw a pest away from your main crop. It only works if you check it and remove the pests before they spread.

Diseases

Chlorosis: Yellowing of leaves that should be green. Disease, poor drainage, cold soil, or a nutrient shortage can all cause it.
Lesion: A spot or patch of damaged tissue on a leaf, stem, or fruit.
Mycelium (mycelial): The thread-like body of a fungus. A white, cottony or web-like mat on stems or soil is usually mycelium.
Necrosis: Dead, brown or black tissue.
Pathogen: A germ that causes plant disease: a fungus, bacterium, virus, or fungus-like water mold.
Physiological disorder: Damage caused by growing conditions, not a germ or insect. Blossom-end rot and catfacing are examples.
Resistant variety: A variety bred to hold up against a specific disease. Seed packets list codes such as V, F, N, or TSWV.
Sclerotia: Hard, seed-like survival bodies some fungi form. They look like tiny mustard seeds or black specks and can last in soil for years.
Spore: A microscopic structure fungi use to spread, like a seed blown by wind or splashed by water.
Vascular wilt: A disease that clogs the plant's water pipes, so it wilts even in moist soil. Cutting the stem often shows brown streaks inside.
Vector: An insect that carries a disease from plant to plant, like cucumber beetles spreading bacterial wilt.

Soil & feeding

N-P-K: The three numbers on a fertilizer bag: percent nitrogen, phosphate, and potash by weight.
Nitrogen fixation: Beans, peas, and clovers working with soil bacteria to pull nitrogen from the air. How much is left for the next crop varies widely.
Organic matter: Decayed plant and animal material in soil. It holds water and nutrients and feeds soil life.
pH: How acidic or alkaline soil is. Most vegetables do best around 6.0 to 7.0.
Side-dress: Feeding a growing crop by placing fertilizer or compost alongside the row.

Growing

Bolting: When a crop like lettuce or cilantro shoots up a flower stalk, usually from heat or long days. Leaves turn bitter.
Broadfork: A wide fork with long steel tines you step on and rock back to loosen compacted soil without turning it over. Useful for heavy clay; most beds don't need one.
Determinate / indeterminate: Determinate tomatoes stop at a set height and ripen in a burst. Indeterminate ones keep growing and fruiting until frost.
Frost date: The typical last spring or first fall frost for your area. It's an odds-based estimate, not a guarantee; check the forecast too.
Hardening off: Moving seedlings outside a little longer each day for about a week so they toughen up before transplanting.
Hardiness zone: A band based on average coldest winter temperature. It tells you which perennials survive winter, not when to plant.
Succession planting: Sowing small amounts every few weeks so harvests keep coming instead of arriving all at once.

Still stuck? Browse the pest guide or the disease library.