Reference

Glossary

Plain definitions of the terms the modules use, from direct sun and frost dates to guaranteed analysis and cover crops.

Each term links to the module that defines it, where it is used in context. Filter by typing part of a word.

Term	Meaning	Module
10 percent date	The frost date that only 1 year in 10 goes beyond: later than the 50 percent date in spring, earlier in fall.	2
50 percent date	The median: in half of past years the last spring freeze came after it, in half before.	2
Action threshold	The level of a pest, or of the conditions that favor it, at which control is worth doing.	10
Amount per person	A published planting figure meant to supply one person's eating of a crop for a season; use it as a ceiling, not a target.	1
Application rate	The depth of water an irrigation system delivers per hour over the area it serves.	8
Buffer pH	A second pH reading a lab takes to measure how strongly a soil resists a change in pH, used to compute the lime requirement.	3
Bush type	A catalog label on a cucumber, squash or melon meaning a compact plant that does not run.	5
Chromated copper arsenate	CCA, the old residential wood preservative, which contains arsenic. It was withdrawn from residential use.	4
Clay	The smallest of the three mineral particle sizes in soil.	3
Cold frame	A low, bottomless box with a clear lid that gathers the sun's heat by day and is closed at night.	12
Compaction	The crushing of those pores, by feet, machines or working the soil when it is wet.	3
Complete fertilizer	A fertilizer with all three label numbers above zero.	9
Composite sample	Many subsamples mixed together into one sample, which stands for the average of the area you scooped.	3
Container	Any vessel with a bottom, from a 1-gallon pot to a half barrel, filled with a soilless mix and cut off from the ground.	4
Cool-season crop	A crop that prefers growing temperatures of about 60 to 80 °F and loses quality in hot weather.	6
Cover crop	A crop grown to protect and improve the soil rather than to eat.	12
Crop family	The botanical family a vegetable belongs to.	5
Crop rotation	Moving each family to a different part of the garden each year, so the same family does not return to the same soil for several years.	5
Crop shortlist	The five to eight crops you commit to for the first season, chosen before you buy seed.	1
Cross-contamination	The transfer of harmful organisms from a dirty surface, utensil, hand or food to a clean one.	11
Cubic yard	27 cubic feet. Cubic yards = cubic feet / 27.	4
Cultivating	Breaking the soil surface between plants with a hoe or hand tool to cut off weed seedlings.	1
Curing	A short holding period after harvest, under set conditions, that prepares a crop for storage.	11
Damping-off	The sudden collapse of a young seedling at the soil line, caused by fungi that garden soil carries.	7
Days to maturity	The number of days a seed company or extension service gives from planting to the first harvest under typical conditions.	5
Determinate	A determinate tomato limits its own size: it grows to a set height, sets its fruit and slows down.	5
Direct sowing	Sowing seed where the plant will grow to maturity.	7
Direct sun	The sun itself is visible from the spot, so the plants cast a sharp shadow.	2
Disease-resistance code	An abbreviation in a seed catalog saying the variety was bred to resist, or tolerate, a named disease.	5
Disorder	Damage from a growing condition (water, temperature, nutrients, light) rather than from a living pest or pathogen.	10
Drip irrigation	Watering that delivers water slowly to the soil at the base of plants through tubing fitted with emitters.	8
Emitter	A fitting that releases water at a fixed rate, rated in gallons per hour (gph).	8
Equidistant spacing	Setting every plant the same distance from all its neighbors, with alternate rows staggered, instead of in rows with wide aisles.	5
F1 hybrid	A first-generation cross between two known parent plants.	5
Fall factor	About 14 days added in the fall planting formula for slower growth in the cooler weather and shorter days of late summer and fall.	6
First flush	The first runoff from a roof in a rain, which carries most of the dust, droppings and debris that settled on it.	8
Food-grade containers	Containers made to hold food.	11
Frass	The excrement and chewed debris insects leave behind; its form and place are a clue to the culprit.	10
Freeze	Air temperature below 32 °F.	2
Freeze-free period	The freeze-free period (or frost-free season) is the number of days between the last spring freeze and the first fall freeze.	2
Frost	In the national freeze tables, a frost is associated with an air temperature of 36 °F. On a clear, still night leaves can frost over while the air at thermometer height is a few degrees warmer.	2
Frost heaving	The lifting of cloves or small plants out of the soil as it freezes and thaws.	12
Frost pockets	Low places among small hills and valleys where cold air pools, so frost forms earlier in fall and later in spring than on the slopes around them.	2
Frost tolerance class	A group of crops that tolerate the same amount of cold and so share a planting window: hardy, semi-hardy, tender or very tender.	6
Frost-tender factor	Another 14 days added in the fall planting formula for frost-sensitive crops, which must mature at least two weeks before frost.	6
Garden brief	The first page of it is the garden brief: a one-page statement of your goals, weekly hours, space, total area, crop shortlist and who helps, plus a sentence in your own words about what would make the season a success.	1
Garden notebook	This course's name for the set of records you keep about your garden: the plan, the soil record, the season log, the problem log and the checklists, all in the tool pages of this site and exportable as one file.	1
Germination rate	The percentage of seeds in a sample that sprout under good conditions.	7
Glycoalkaloids	Natural toxins (solanine and chaconine) in every part of the potato plant, highest in sprouts, leaves, flowers, eyes and green skin. Cooking does not destroy them.	11
Grade	The three numbers on a fertilizer label: the percent by weight of nitrogen (N), phosphate (P2O5) and potash (K2O), always in that order.	9
Green manure	Another name for a cover crop that is turned into the soil in spring to add organic matter.	12
Ground contact	A rating on treated lumber, stated on its label or end tag, for wood that will touch soil.	4
Guaranteed analysis	The block of text on a fertilizer label that lists the grade, with the forms and sources of each nutrient.	9
Hard freeze	Air temperature below 28 °F.	2
Hardening off	The gradual exposure of indoor-grown seedlings to outdoor sun, wind and temperature before planting.	7
Hardiness zone	A band on the USDA Plant Hardiness Zone Map defined by the average annual extreme minimum winter temperature: the coldest night of each year, averaged over many years.	2
Hardy	Crops that grow with daytime temperatures as low as 40 °F and may survive a frosty night.	6
Harvest period	How many days you want to keep picking before frost.	6
Heavy feeder	A crop that extension sources single out for a higher nutrient rate than the general garden figure.	9
Hill	A hill in a planting guide is a small group of seeds sown together at one spot, usually for vining crops, not necessarily a raised mound.	1
In-ground bed	The existing soil, cleared and improved where it lies.	4
Indeterminate	An indeterminate tomato keeps growing taller through the season and keeps producing fruit all summer.	5
Integrated pest management	The approach extension services and the U.S. EPA teach for plant problems: prevent, scout, identify, decide on a threshold, act with the least-risk option, and check the result. It can include pesticides, and puts them last.	10
Interplanting	Growing two or more crops in the same place at the same time.	5
Jar test	The jar test separates a soil sample into its three particle sizes by letting them settle out of water.	3
Leaching	The loss of dissolved nutrients downward, below the roots, with water that drains through the soil.	9
Lime requirement	The amount of lime needed to bring a soil to the target pH, computed by the lab from the pH and buffer pH.	3
Low tunnel	A row cover or plastic sheet held above a row on hoops, so the cover does not rest on the leaves.	12
Macronutrients	Nitrogen (N), phosphorus (P) and potassium (K): the three elements plants need in amounts large enough that fertilizer is sold by them.	9
Manure-to-harvest interval	The time between applying raw manure and harvesting a crop: 120 days for crops that touch the soil and 90 days for others, per Iowa State and Maine Extension.	11
Microclimate	The climate of a small area, such as one corner of a yard, that differs from the climate around it.	2
Milk stage	The stage at which sweet corn is picked: kernels near full size, and a kernel pierced with a thumbnail releases a milky liquid.	11
Mulch	A layer of material spread over the soil surface around plants.	8
Natural enemy	An organism that kills, reduces the reproduction of, or otherwise reduces the numbers of another organism.	10
Organic matter	The part of the soil that comes from living things: roots, leaves, compost, manure, and the bodies and byproducts of soil organisms, in every stage of decay.	3
Parasitoid	An insect that lays eggs in or on another insect; the young feed on it and kill it.	10
Parts per million	The unit lead results come in (ppm), the same as milligrams per kilogram (mg/kg).	3
Pesticide	Any product used to kill, repel or control a pest: insects, slugs, fungi, weeds or animals, including organic and homemade products.	10
pH	A measure of how acidic or alkaline the soil is.	3
Potting up	Moving a seedling into a larger container before its roots fill the first one.	7
Pressure regulator	A fitting that lowers and steadies the water pressure from the tap; part of every drip system.	8
Pressure-treated wood	Lumber with a liquid preservative forced into it under pressure.	4
Raised bed	Soil lifted above the surrounding grade, usually held in by a frame of wood, metal, block or stone.	4
Relative humidity	How much water vapor the air holds, as a percentage of the most it could hold at that temperature.	11
Relay planting	Sowing the same crop several times a few weeks apart so the harvest is spread out (Virginia's "relaying").	6
Root zone	The volume of soil that a plant's roots occupy and draw water from.	8
Rotation map	A drawing or table of each bed or zone with the family planned for it in each of the next three or four years.	12
Row cover	A lightweight, spun-bonded fabric laid over plants, or over hoops above them, that lets light, air and water through but keeps insects and some animals off.	10
Runoff	Water that flows over the soil surface instead of soaking in, carrying soil particles, and whatever nutrients are attached or dissolved, toward drains and streams.	9
Sand	The largest of the three mineral particle sizes in soil.	3
Scouting	A deliberate walk past every plant to look for insects, damage, disease and stress, done on a schedule rather than when something looks wrong.	1
Screening level	A concentration that agencies use to decide when a site needs a closer look or a change in use.	3
Season extension	Protecting crops so they can be planted earlier in spring or kept growing later in fall than open ground allows.	12
Season review	A written comparison, done once at the end of the season, between what you planned and what your records show happened.	12
Semi-hardy	Crops that grow with daytime minimums of 40 to 50 °F and are less tolerant of a frosty night than hardy crops.	6
Settling	The loss of volume as loose fill packs down and organic matter breaks down. How much a product settles depends on the product.	4
Shelf life	How long a crop keeps in good condition under its storage group's ideal conditions.	11
Side-dressing	Applying fertilizer beside growing plants, in a band along the row or a ring around each plant, partway through the season, rather than mixing it in before planting.	9
Signal word	The word on the front of a pesticide label that ranks its short-term toxicity.	10
Silt	The middle of the three mineral particle sizes in soil.	3
Slow-release fertilizer	A fertilizer formulated, or made from materials, that release nitrogen over weeks rather than days.	9
Smothering	Killing turf by covering it with cardboard or newspaper and a few inches of compost, and waiting several weeks before planting.	4
Soaker hose	A porous hose that seeps water along its whole length rather than at fixed points.	8
Sod	The turf layer: grass with its roots and the soil they hold.	4
Soil structure	The way particles bind into larger crumbs and clods, and the pore spaces between them.	3
Soil texture	The proportion of the three in a soil is its soil texture.	3
Soilless mix	A blend of materials such as sphagnum moss, composted bark, perlite, vermiculite or coconut coir, used in containers instead of garden soil.	4
Storage group	A set of crops that keep best under the same temperature and humidity.	11
Subsample	One scoop of soil taken for a soil test; many are mixed into one composite sample.	3
Succession planting	Sowing a short row of a quick crop every week or two instead of all at once, so the harvest comes in a stream. Virginia Cooperative Extension also uses the term for planting a new crop in the space a finished one leaves.	1
Sun map	A sketch of the candidate spot with the hours of direct sun recorded at several points, made by checking the spot at fixed times through one day.	2
Tender	Crops that need daytime temperatures above 55 °F and do not tolerate frost.	6
Texture triangle	The standard chart that names a soil, such as "clay loam," from its sand, silt and clay percentages.	3
Thinning	Removing extra seedlings so the ones that remain stand at the packet's final spacing.	7
Topsoil	Mineral soil, with its sand, silt and clay, sold for filling beds, usually blended with compost.	4
Transplant	A young plant started in a container, indoors or in a greenhouse, and moved into the garden.	7
Transplant age	The number of weeks from sowing a seed indoors to a plant ready to set out.	6
True leaves	The leaves that appear after the first pair of seed leaves and have the shape of the crop's mature leaves.	7
Very tender	Crops that do not tolerate frost or cool spring winds and need daytime temperatures above 60 °F.	6
Viability	The ability of a seed to germinate and grow into a normal seedling.	7
Warm-season crop	A crop that prefers summer weather of about 70 to 95 °F and cannot tolerate frost.	6

Limits

These are the meanings this course uses. Labels, seed catalogs and other publications sometimes use a term more loosely or more narrowly; where it matters, the module says whose definition it follows.