Glossary of Gardening Terms and Concepts

Annual

A plant that completes its life cycle within one growing season; going from seed, to a mature fruit-producing plant, to a dried fruit/seed that can be harvested for planting next year’s crop. Most horticultural crops such as tomatoes, beans, and cucumbers are grown as annuals and require a new planting every year.

Beneficial Insects

Insects that provide some sort of positive effect for a plant. For example, bees, butterflies, and wasps are considered beneficial insects because they aid in pollination. Other types of beneficial insects act as an organic pest control method. One example would be ladybugs, which prey on common garden pests such as aphids, whiteflies, mites, fleas, and potato beetles. Other beneficial insects that may be used as a natural pest control include praying mantises, spiders, ground beetles, and many more.

Biennial

A plant that requires two years to complete its life cycle. The first year is dedicated to growth and the second year is dedicated to reproduction and seed production before it dies. Carrots and Brussels sprouts are biennials.

Bolting

The condition of premature flowering on a plant before it is harvested, often making the crop inedible. Bolting, or “going to seed,” occurs in many cool-season plants as temperatures warm and the days lengthen, triggering their reproductive phase and causing the plant to flower and produce seed. This commonly occurs in plants such as lettuce, carrots, cabbage, arugula, spinach, and herbs like basil, dill, and cilantro. Consider applying mulch, using shade cloth, and/or intercropping cool-season plants with taller crops to provide shade to keep the soil cool and prevent bolting.

Chilling Hours

Some plants require a certain number of hours below a specific temperature (dependent on plant type and even variety) in order to flower and produce fruit. This is an essential period of dormancy or rest for the plant before resuming fruit production. Blueberries are a good example of a plant that requires chilling hours in order to begin flowering in the spring and then produce fruit during its season. If a blueberry bush does not receive enough chilling hours, it will either fail to produce fruit or set fruit very poorly and shorten the life of the plant.  Select varieties with annual chill hours that match what the growing area typically receives; see the map of Louisiana below to aid in selection.

Companion Planting

This is a technique of planting two different crops together to benefit each other. Companion planting is often done using crops whose growth cycles benefit one another in order to reduce the need for pesticides or nutrient additives. For example, when radishes are planted around young broccoli transplants, the radishes quick growth cycle allows them to prevent weeds by shading the soil as the broccoli grows; and the radishes are harvested by the time the broccoli is large enough to shade out weeds on its own. Another example is planting legume crops (e.g., beans) alongside a non-legume crop (e.g., squash). Legumes fixate nitrogen into the soil, which is beneficial for most plants. Another common form of companion planting is sowing flowers that attract pollinators next to crops that require insect pollination.

Compost

Broken-down organic material that often has beneficial nutrients for plants as well as microbes. It is usually made by combining carbon (such as fallen leaves) and nitrogen (such as kitchen scraps), along with some soil, into a pile on the ground or in a special container that is then allowed to sit and decompose over time, occasionally being turned and watered so that it decomposes evenly. This is a great method to reduce landfill waste while introducing soil biology and added nutrients to a garden.

Cover Crops

Fast-growing plants that are utilized for one or more of their soil-enhancing qualities or other properties such as weed suppression. Cover crops are often grown during the off-season or in between crops to reduce nutrient loss and soil erosion. There are many benefits to cover crops, such as reducing weed pressure, adding nutrients to the soil, reducing pest and disease pressure, and providing organic matter to the soil once the crops are cut down and integrated into the soil. For example, growing soybeans (a legume) as a cover crop reduces weed growth and fixates nitrogen into the soil, and when incorporated into the soil provides a rich source of organic matter. Common cover crops are grains, legumes, and grasses, often used in the summer in the South (examples include sudex, southern peas or cowpeas, and millet).

Crop Rotation

The practice of varying successive crops on the same plot of land, especially to avoid depleting the soil of nutrients; to decrease disease, insect pests, and weed pressure; and to improve soil health. Each season, crops should be rotated by plant family to another part of the field or garden, making sure to avoid planting a crop in the same plant family sequentially in the same plot. Members of the same plant family are susceptible to the same diseases, so to avoid perpetuating a disease, another member of that family should not be planted in the same row for several years. In another example, plant a crop with heavy nutrient requirements such as tomatoes or corn to follow a nitrogen-fixing plant such as beans (legume). A simple crop rotation may be 2-3 crops from different plant families, or with more diversification, a complex rotation of many plant families may be used.

Cultivar

A variety of a crop created through human selection and breeding rather than found in the wild. Cultivar stands for “cultivated variety.” Many cultivars are selected for particular features such as heat or cold tolerance, disease or pest resistance, or other desirable traits such as enhanced taste or color.

Cultivation

The active practice of working the soil. Methods such as tilling, plowing, or using a shovel or broad fork are used to prepare the soil for planting, aerate the soil, and reduce soil compaction.  This also refers to shallowly working the soil surface by hand or with tools to break up the soil surface or reduce weeds. Over-cultivation can be harmful to the soil as it disrupts the natural soil structure and may lead to compaction, erosion, and destruction of beneficial microbes. 

Determinate

Refers to plants that stop growing and increasing in size once they reach their reproductive stage, or “determined” growth. The plant will first go through a phase of vegetative growth, and then it will halt growth and begin fruiting. Determinate tomato plant varieties are a good example, as they will reach a set height before beginning to fruit, resulting in all fruit ripening near the same time for a shorter harvest period. Alternatively, indeterminate tomatoes will continue to grow while fruiting. Other examples of determinate plants include certain cucumber varieties and bush snap beans.

Direct Seeding (outside)

Direct seeding is the process of seeding a plant directly into the soil where it will grow to maturity. This is often done for crops that do not transplant well such as carrots, radishes, and squash, though most plants can be direct seeded with varying success.

Domestication of Crops

A process of adapting wild plants for human use that began almost ten thousand years ago, though most horticultural crops were domesticated within the past hundreds, rather than thousands, of years. Domestication began as humans harvested and replanted crops with more desirable traits (e.g., taste, yield, storage ability), which, over time, changed the crops genetically to the point where they were very different from their wild relatives.

Fertilization

The act of adding nutrients into the soil for plants to access. Fertilization is often necessary when gardening to supplement the soil before planting and during plant growth, as nutrients are depleted to increase fruit yield and quality. Most general fertilizers only focus on the three macronutrients a plant needs: nitrogen, phosphorous, and potassium (N, P, K).  However, there are also fertilizers that include magnesium (Mg) and calcium (Ca), along with a variety of micronutrients such as iron, copper, and zinc. Take care to avoid over-fertilization as an imbalance in the nutrient ratio in the soil can cause poor growth or plant damage.

Organic fertilizers such as compost, fish emulsion, composted poultry litter or manure, worm castings, and blood or bone meal originate from living organisms. They are easily accessible and far more environmentally sustainable and safe than traditional synthetic fertilizers. They naturally release nutrients more slowly and over a longer period of time.

Sidedressing is the addition of fertilizer to the soil around already established plants. For many plants, sidedressing is done primarily to provide nitrogen, as it is a macronutrient that is often leached out of the soil, especially in conventional growing. Some plants may need additional nutrients as they grow.

Grafting

A horticultural technique used to propagate fruit trees using asexual reproduction to ensure that desired characteristics (e.g., dwarfing, cold hardiness, tolerance to wet soils) are maintained. The top part (scion) is cut from the cultivar of interest (or parent tree) and placed on a compatible rootstock. The grafted plant has the vascular tissues from the selected variety and the rootstock growing together. An example is citrus, with the top part being the variety of interest, such as a Browns Select satsuma, grafted onto Poncirus trifoliata (called trifoliate orange) rootstock. Trifoliate orange provides added tolerance to adverse soil conditions and cold temperatures.

Hardiness

Refers to a plant’s ability to survive adverse temperatures such as cold, heat, drought, flooding, or wind as a measurement of hardiness. The term most often describes resistance to cold, or “cold hardiness,” and is measured by the lowest temperature a particular plant can withstand without severe damage or death. Hardiness ratings are often published with zones for geographic regions based on their average minimum temperatures. The average first freeze in the fall/winter and first frost-free date in the spring are other indications of plant hardiness. An example is the difference in cold hardiness for citrus types, as shown in the graphic below of Louisiana’s three zones, based on risk of hard freezes for citrus production. Citrus is best adapted to Zone A. By selecting cold-hardy types and providing adequate cold protection, citrus can be successful in Zone B. In Zone C only a few types can be grown, with extensive cold protection measures necessary in most years. 

Hardening Off

Hardening off is the process by which transplants started inside or in a greenhouse are acclimated to harsher conditions such as temperature, wind, moisture, and sunlight outside.  This “toughening-up” process is often done by setting transplants outside for increasing periods of time in the sun, by reducing the water given to them (though not to the point of wilting), and sometimes by reducing fertilizer. Hardening off can take place for a few days to a week prior to planting outside. General instructions for hardening off transplants include placing the seed tray outside, gradually increasing the amount of direct sunlight exposure every day, and bringing the tray inside each night. Do not put seed trays outside if the temperature is below 50 degrees F or on windy days.

Harvest

Harvesting crops is the final step in the garden when produce is fully matured and ready to be picked and properly stored. It is best to harvest in the morning, as temperatures are cooler and the crops will be crisp and higher in water content. Avoid harvesting during the heat of the day. Harvested crops should be stored out of the sun, in a cool area. Shake off excess dirt, but do not wash until ready to eat. Handle produce with tender skins, like summer squash and tomatoes, carefully. Vegetables with thick skins, like potatoes, winter squash and onions, will have an improved shelf life after drying (curing) for a few days in the shade or inside.

Heirloom

Heirloom crops are ones whose seeds have been saved each season for at least 50 years and are open-pollinated. Many heirloom varieties have superior or unique flavor and appearance compared to non-heirloom varieties, but they are often more susceptible to pests and disease. For most crops, heirloom varieties are available, and perhaps the most common are heirloom tomatoes.

Hybrid (F1)

Varieties of crops that have resulted from a controlled method of pollination in which the pollen of two different species or varieties is crossed by humans. Hybrid varieties have been bred to have specific traits such as earlier production, higher yields, and improved insect and disease resistance compared to open-pollinated (OP) varieties, and to have more uniform production and wider adaptability. Hybrid seed is often more expensive, and the seed cannot be saved as the resulting offspring will not be true-to-type and may be less vigorous. Gardeners who use hybrid plant varieties must purchase new seed every year. 

Indeterminate

Refers to plants that do not stop growing once they reach their reproductive stage, or continue to grow “indeterminately.” The plant will first go through an initial phase of vegetative growth, and then it will go through reproduction while continuing to grow. Indeterminate tomato plants are a good example of this, as they will continue to grow while producing fruit, resulting in a longer harvest period and requiring a tall, strong trellis and pruning. Other examples include certain cucumber varieties and pole snap beans.

Integrated Pest Management (IPM)

This ecosystem-based prevention strategy focuses on maintaining a healthy soil and crop that in turn will reduce pest and disease pressure. Combining pest and disease control techniques with organic/natural alternatives also minimizes risk to people and the environment. Monitoring the garden is essential to the identification of pest and disease pressure and for determining a management strategy. By combining a variety of sustainable techniques such as establishing damage thresholds; beneficial insects; mulching; weeding; nutrient management; adequate watering; and selecting varieties with greater pest/disease resistance, one can greatly reduce the need for chemical pesticides.

Irrigation

Irrigation is used to provide water to crops when rainfall is not sufficient. There are many different ways to irrigate crops, from a simple sprinkler or overhead watering system, to flooding the space between rows, to drip irrigation. Drip irrigation uses a soaker hose or perforated tubing to provide a small but steady amount of water directly to a plant’s base, using less water more efficiently and keeping the plant’s foliage dry, therefore lessening disease risk. Overhead watering increases risk of foliar disease and is less efficient than drip irrigation.

Louisiana Pesticide Law

Regulates the use of pesticides (e.g., insecticides, herbicides, fungicides, rodenticides) in schools to protect children and staff from exposure to chemicals in and around schools and is enforced by the Louisiana Department of Agriculture and Forestry (LDAF). The law encourages schools to use Integrated Pest Management (IPM). The Louisiana Pesticide Law applies to all public and private elementary and secondary schools (K-12) in Louisiana. Requirements include pesticide applications to be conducted only by a registered pesticide applicator following required guidelines. In addition, each school authority shall prepare for each school under its authority an annual IPM plan. More information is available here: Louisiana Pesticide Law (Louisiana Department of Health).

Media

Media is a term that generally refers to soilless planting mixes. It is often composed of peat moss (a highly absorbent, organic base to the mix), perlite (which helps provide aeration and moisture retention), and vermiculite (increases nutrient-holding capacity) in different ratios based on the purpose. Media may also have compost (high in nutrients), a small amount of bone/blood meal or another fertilizer, and a wetting agent. A soilless medium is what is primarily used for filling seed germination trays when preparing transplants, since it is sterile and usually more suitable to the needs of young plants than soil.

Mulch

Refers to a layer of material covering the soil surface to conserve soil moisture, improve the fertility and health of the soil, reduce weed growth and soil erosion, moderate soil temperatures, and often improve yield, fruit size, and quality. Mulch can be organic materials such as leaves, pine needles, hay, and straw (which also add organic matter over time), or synthetic mulch, which is made from clear, black, or reflective polyethylene plastic. Black plastic mulch is recommended to increase soil temperature (for use in cool seasons), white plastic to reflect the sun and keep soil cooler (for use in warm seasons), and reflective mulch to repel certain insect pests. Synthetic mulch should be placed on top of the soil, with small holes cut to transplant or direct seed at the recommended spacing distance (see image below).

Open-Pollinated (OP)

Refers to varieties in which pollination occurs by insect, bird, wind, humans, or other natural mechanisms.  Offspring will have similar characteristics to the parents (i.e., genetically stable). Open-pollinated (OP) plants are more genetically diverse, with variation within plant populations, which allows plants to slowly adapt to local growing conditions and climate year-to-year. Because they breed true (produce offspring nearly identical to the parent plant) if not cross-pollinated by a nearby related variety, the seeds of OP plants are often saved by home gardeners.

Organic Production

The growing of plants in harmony with nature and natural cycles, without using synthetic fertilizers, pesticides, herbicides, or other such products and using sound, environmentally friendly horticultural practices. Certified organic production uses methods approved by the USDA National Organic Program and must meet certain requirements such as not using synthetic fertilizers, pesticides, and other additives as well was maintaining soil health. Seeds that are labeled as organic come from plants that were grown organically.

Parthenocarpic

Plants that produce fruit without the ovules of the flower being fertilized or pollinated, resulting in a seedless fruit. This is a highly desired trait in certain crops such as watermelon and cucumber, and especially cucumber varieties that are grown in a greenhouse (where pollinators may be excluded).

Perennial

A plant that lives for two or more years and produces a crop multiple times over its lifespan rather than living and dying in one or two seasons. Most trees and shrubs, such as citrus and blueberries, are perennials.    

Phytochemicals

Chemicals produced by plants (“phyto”) to prevent disease, hold off predators, and maintain greater health. Crops with phytochemicals have long been used for medicinal purposes and may have great health benefits for humans. One example is carotenoid, a phytochemical found in red, orange, yellow, and green crops (such as carrots, tomatoes, squash, and broccoli) that may prevent cancer and cardiovascular disease while boosting immunity. Another example are the flavonoids, which may combat inflammation and tumor growth and can be found in some fruits (berries, apples, citrus) as well as onions.

Plant Family

A plant family is the scientific categorization given to groups of plants that are genetically or evolutionarily related and exhibit similar traits in growth, reproduction, appearance, and more. Knowing the different plant families is extremely beneficial for planning crop rotations, since plants within the same family often have the same nutrient needs and are at risk from the same pests and diseases.

Pollination

Pollination occurs when pollen from the male flower (or male part of a flower) is transferred to the female flower (or female part of the same flower). Pollination can occur in a variety of ways, depending on the plant. Some plants are self-pollinated, meaning that the plant contains all necessary components for the flowers to pollinate themselves (e.g., tomatoes and peppers). Other plants (such as most fruit trees) require cross-pollination, which means that one plant or flower will need to be pollinated by another plant or flower of the same species (but usually a different variety). Pollination can either occur via wind or by an insect pollinator visiting the male flower and then transferring pollen to the female flower, which in turn will produce fruit.

Pollinators

Honey bees or native pollinators are essential for pollination of many crops (such as the cucurbits) that require cross-pollination for fruit development. Often native solitary bees, bumble bees or other insects serve as pollinators, and the imported European honey bee (Apis mellifera) from managed hives in the area is a major pollinator for fruit and vegetable crops. Pollinating insect populations may be adversely affected by insecticides applied to flowers or weeds in bloom. It is recommended, if insecticides must be used, to apply only in the evening hours when bees are no longer foraging. Planting flowers and herbs near the garden is helpful to attract pollinators.

Row Cover

Semitransparent, flexible material made from clear plastic (polyethylene) or spunbonded polyester fabric can be used as a covering to protect plants from the undesirable effects of cold, wind, and insect damage, while also retaining some ground heat. Row covers are effective in modifying the microclimate around the plants and are used to optimize plant growth and development. Row covers can be “floating” lightweight materials on top of the plants or directly above rows of crops on a supporting framework — often wire hoops to form low tunnels. Row covers should be removed from plants that require insect pollination, such as cucurbits, when flowers are present, as they interfere with pollinator activity.

Scientific (Latin) Name

This name uniquely labels a species according to genetics, evolution, appearance, growth, and reproductive traits, among other things. Because there is such great variety in common names of plants, the scientific (Latin) name avoids confusion and provides consistency across diverse languages and regions.

Seed Germination Trays

These are often used to start seedlings that will later be transplanted into a garden or field. By starting seeds in a germination tray, one can get a head start on growth by placing them in a controlled environment suited to the plant’s needs, even when temperatures outside may not be suitable. It is recommended to use trays that are at least 1.5 inches in diameter (see image below). The use of smaller pots or cells will reduce the time that transplants can be maintained in trays, will restrict root growth, and may reduce success when transplanting.

Seed Saving

Every crop, for the most part, produces seed that can be saved to plant in future seasons. When planting more than one variety, isolation distance recommendations should be followed to decrease the chance of cross-pollination when saving seed from non-hybrid varieties. Most hybrid (F1) crops will not produce seed that is true to the characteristics of the parent plant. Seeds should be stored at a certain temperature and humidity level in order to maintain optimal viability. In general, cool and dry conditions are best for storing seed. 

Seedlings

Seedlings are immature plants that have recently germinated. Seedlings will have cotyledons, the small leaves that first emerge when a seed germinates and breaks through the soil. As the seedling grows, it will develop its first true leaves. The true leaves of a seedling are the leaves that are characteristic of its species, versus the cotyledons.

Soil Composition

In general, most soils are composed of four main components in the following proportions: air (~25%), water (~25%), minerals (~45%), and organic matter (~1-5%). In order to sustain plant life, the proper mix of air, water, minerals, and organic material is required. The organic material in soil is composed of microorganisms (dead and alive) and decaying plant material. The mineral fraction is made up of mineral matter that began as rock and was weathered into small particles over time. These soil particles are divided into sand, silt, and clay particles, according to their size and arrangement.  The composition of soil is important for nutrient management. Soil minerals and organic matter hold and store nutrients.  Additional nutrients in the soil water are taken up by plants to be used for growth and development. The air in the soil also plays an integral role since many of the microorganisms that live in the soil need oxygen to undergo the biological processes that release additional nutrients into the soil.

Soil Health

Soil health is the ability of the soil to support a living system. This includes supporting plant and animal health and productivity, ecosystem wellness, and water and air quality. Sustainable techniques such as composting, cover cropping, and crop rotation work together to build soil health. Soil pH refers to the acidity or basicness (alkalinity) of the soil. pH ranges on a scale from 0 to 14 with zero being extremely acidic and 14 being extremely basic (alkaline). Different nutrients are more or less available to a plant depending on the pH of the soil, and a pH that is too acidic or basic for a plant can result in plant death. Most plants prefer slightly acidic (6) to slightly basic (7.5) pH. If the soil pH is too acidic, materials like limestone can be used to make it more basic (less acid). If the pH is too basic, elemental sulfur can be used to correct it. See the figure below, which shows the relationship between nutrient availability and soil pH and demonstrates the importance of having a suitable soil pH for the crop.

Soil Testing

Soil testing is often done to determine the pH, nutrient, and organic matter levels of the soil. This is done by collecting samples (called soil cores) from the area of interest and sending the sample(s) to a lab to be tested. Soil testing is extremely beneficial and worthwhile when gardening or farming, because it allows one to directly pinpoint any issues related to pH, nutrients, or organic matter in the soil. The LSU AgCenter has soil testing capabilities and provides recommendations for nutrient management for specific crops. It is recommended to send soil samples periodically for testing. 

Soil Texture

The proportion of the three sizes of soil particles (sand, silt, clay) and the fineness or coarseness of a soil. The texture of the soil influences its ability to support plants, as it often determines the amount of water and air the soil can hold and how easily water can move through the soil. The most ideal soil texture is loamy soil, which contains roughly equal amounts of sand, silt, and clay. Plants can still do well in soil that is not perfect loam. See the figure below depicting the soil texture triangle, showing the 12 major textural classes as defined by the USDA.

Succession Planting

Planting again 1-3 weeks after the initial sowing, in order to ensure a continuing harvest. Succession plantings may be made until the close of the suggested planting dates. Consult planting guides for the optimal planting dates for each crop.

Sustainable Gardening

Gardening that minimizes environmental impacts by using sound horticultural techniques to manage water and nutrients wisely, recycle garden wastes, improve and protect the soil, encourage beneficial insects and biological diversity in the garden and manage pests and diseases through cultural practices like proper spacing, planting times, crop rotation and Integrated Pest Management when necessary.

Thinning

Thinning is the process by which you remove extra seedlings from an area to ensure proper spacing. Since many seeds do not have 100% germination, over-seeding is done to ensure enough plants germinate to make a good “stand.” Thinning is a common practice, especially for crops like carrots, beets, lettuce, and radish and when using old seed. Once seeds have germinated and grown a few inches, any extra plants need to be removed (thinned out) to ensure proper spacing and to avoid crowding.

Transplant

Transplants are plants that are grown in a separate container or tray/area before being planted in their final place in the garden. Transplants are a great way to give more control and predictable results in the garden, and to extend the season, since they can be started indoors or in a greenhouse when the weather is still unfavorable outside. For example, broccoli transplants can be started 6-8 weeks earlier indoors than they could be direct-seeded outdoors. Once the temperatures have cooled enough for the broccoli to be planted outdoors, the transplants are already 6-8 weeks old and will mature earlier in the season and provide an earlier crop than they would when direct-seeded outside.

Trap Cropping

A trap crop is a plant that attracts insects away from desirable nearby crops. It is a form of companion planting that can save the main crop from devastation by pests without the use of pesticides. Although some crops are regular targets for specific insects, pests can be outsmarted if another tastier crop is planted nearby. There are many examples of using this technique to reduce pest damage on desired plants. If sunflowers are blooming near tomatoes, stink bugs prefer the sunflowers. A few field pea plants will also be more attractive to stink bugs. Flea beetles prefer feeding on the tops of radishes or mustard greens to the leaves of eggplants. Research the days to harvest of different crops and time them to coincide, attracting pests away from desirable crops. When the trap crops are infested with the target pest, spray an organic pesticide or, to be more environmentally friendly, carry a battery-powered vacuum (dust buster) into the garden and remove the pests.

Untreated Seed

Seed that has not been chemically treated with a fungicide or insecticide prior to packing. Many seeds sold commercially are untreated seeds and this is identified on the label. Some species are extremely susceptible to certain diseases at the seedling stage; therefore, treated seed may be the better option. Treated seed is usually more expensive than untreated seed.

Varieties

A variety of a plant species is one that consistently has a distinguishing characteristic when compared to the regular version of its species. Varieties of a plant species are ones that occur naturally in the wild rather than being man-made and will produce seed true to their unique characteristics. It is suggested that the word “cultivar” be used for man-made varieties, although both terms are used interchangeably by gardeners.