Hardy Plants Plants adapted to winter temperatures or other climatic conditions of an area. Half hardy indicates some plants may be able to take local conditions with a certain amount of protection.

Heaving Caused by alternate freezing and thawing of the soil during winter. This action can push small plants out of the soil and damage their root systems.

Heavy Soil Soil containing large amounts of clay. Such a soil retains moisture, should not be cultivated when wet, and can be improved by adding organic material.

Hedgerow Single row of shrubs or trees which provides a screen or wildlife food and cover, improves the landscape, or serves as a fence or a windbreak.

Heeling In Temporary storing of bare-rooted trees and shrubs by placing the roots in a trench and covering with soil or sawdust.

Herbaceous Plant Plants that die back to the ground each winter, such as asparagus and rhubarb.

Herbicide Chemical used to control weeds and undesirable vegetation.

Hill Raising the soil in a slight mound for planting, or setting plants some distance apart.

Host Plant Plant on which an insect or a disease-causing organism lives.

Hot Caps Waxpaper cones, paper sacks, cardboard boxes or plastic jugs with bottoms removed placed over individual plants in spring for frost and wind protection.

Hotbed Same type of structure as a cold frame but heated, as with an electric cable.

Humidifier Air passes through wet material and evaporates water. Humus Decomposed organic material that improves texture and productive qualities of garden soils. Hydroponics Growing plants in nutrient Solutions rather than soil. Also called soilless gardening.

Hybrid FI Plants of a first generation hybrid of two dissimilar parents. Hybrid vigor, insect or disease resistance, and uniformity are qualities of this generation. Seed from hybrid vegetables growing in your garden should not be saved for future planting. Their vigor and productive qualities are only in the original hybrid seed.

Immune Free from disease infection because of resistance. Not subject to attack by a specified pest. Immunity is absolute.

Indeterminant Tomato Terminal bud is always vegetative, thus the stem grows indefinitely. Incleterminant plants can be trained on a trellis, a stake, or in wire cages. (See Determinate Tomato).

Indigenous Native to a particular region. Opposite of exotic.

Inflorescence Entire floral structure of a plant.

Inoculation Treatment of seed with bacteria that stimulate development of bacteria nodules on plant roots. Used on legumes such as peas and beans.

Inorganic Mineral content of the soil. In reference to fertilizers, those produced chemically. Not arising from natural growth.

Insecticide Chemicals or agents used to control insects either on contact or as a stomach poison.

Internode Region on a plant stem between the nodes.

Interplanting Getting maximum production from a garden by planting early maturing vegetables between rows of slow maturing vegetables. An example is radishes or onions between rows of sweet corn.

Irrigation Applying water to the soil by sprinklers, trickle or flooding. K Symbol for potash.

Lath house Structure built of wood lath for protecting plants from too much sunlight or frost.

Layering Way of propagating plants vegetatively. A stem is bent down and buried in a rooting medium to induce root development along the buried portion.

Leaching Loss of soluble fertilizers, or removal of excess soluble salts, by percolating action of water downward through the soil.

Leader Central and dominant stem or trunk of a tree or shrub from which the side branches develop.

Leaf Mold Partially decayed leaves useful for improving soil structure and fertility.

Leggy Weak-stemmed and spindly plants with sparse foliage caused by too much heat, shade, crowding, and over-fertilization.

Legume Plant that takes nitrogen from air with the nitrifying bacteria that live on its roots. Examples are garden peas and beans.

Lifting Digging a plant for replanting or winter storage.

Light Soil Soil that is easy to cultivate, retains little moisture, and has sandy or coarse texture.

Lime Compound containing calcium and/or magnesium, applied to soils to reduce acidity.

Loam Soil that consists of less than 52% sand, 28% to 50% silt, and 7% to 27% clay, resulting in a soil texture ideal for gardening.

Manure--Animal waste used as soil conditioner and fertilizer.

Micro-climate Climate of a small area or locality as compared to a county or State. For example, the climate adjacent to the north side of a home, or influence of a lake on a portion of a county.

Micro-organism Any microscopic animal or plant that may cause a plant disease or have the beneficial effect of decomposing plant and animal residue that becomes humus.

Mildew Plant disease caused by several fungi, recognized by the white cottony coating on plants.

Minor Elements See Trace Elements.

Miscible Oils Oils that mix with water. Used to control scale insects.

Mist Applying vaporized water to cuttings in the propagating stage.

Mites Extremely small sucking insects that infest various plants.

Monoecious Plants that have male and female sex organs in different flowers on the same plant, such as cucumbers and squash.

Mosaic Virus disease that damages or kills plants, often giving the foliage a mottled appearance. Some mosaics can be spread by sucking insects, and some by handling or tools.

Mulch Materials such as straw, leaves, lawn clippings, sawdust, black plastic sheets, or newspapers laid on the soil surface to conserve moisture, maintain an even soil temperature, and control weeds.

Nematode Microscopic, worm-like, transparent organism that can attack plant roots or stems to cause stunted or unhealthy growth.

Nicotine Tobacco extract used as insecticide for controlling sucking insects such as aphids.

Nitrogen One of plant nutrients essential for growth and green color in plants. Available in both organic and inorganic forms. Designated by the letter N.

Nitrogen Fixation Transformation of nitrogen from the air into nitrogen compounds by nitrifying bacteria on the roots of legumes.

NPK Symbols for three of primary nutrients needed by plants. N is for nitrogen, P for phosphate, K for potash or potassium. Percentage of these nutrients in a fertilizer package is always listed in that order.

Node Region of a plant stem that normally produces leaves and buds.

Nutrient Solution Liquid containing some or all essential plant nutrients required for growth. Type of solution used in hydroponic culture.

Oil Sprays Compounds of mineral or vegetables oils used to control scale and other insects on trees and shrubs.

Organic Matter Portion of soil resulting from decomposition of animal or plant material. Helps to maintain good structure and micro-organisms in soil. Tends to give soil a darker color.

P Symbol for phosphate.

Pan Shallow flower pot used for germinating seeds and for forcing and growing bulbs.

Parasite Plant or insect that attaches itself to another organism and obtains food from the host. Dodder is an example of a parasite plant.

Parthenogenic Fruit produced without fertilization of the ovule(s). Usually seedless. (See Fertilization 1).

Patented Plant varieties protected by a government patent, granting exclusive rights to the patent holder.

Peat or Peat Moss Partially decomposed plant life taken from bogs and used as rooting medium, soil conditioner, or mulch.

Peat Pot--Made of compressed peat and often used for starting and growing plants that can be later planted in the garden without removing the pot.

Perennials Any plant which normally lives more than two years. Examples are artichoke, asparagus, raspberry, and rhubarb.

Perlite Volcanic or silica material expanded by heat treatment. Used as a soil amendment and in media for rooting cuttings. (See Rooting Media).

Pesticide General term for any chemical used to control pests.

Pesticide Residue Material that remains on a plant after pesticide application.

pH Chemical symbol used to give relative acidity or alkalinity of the soil. The scale ranges from 0 to 14, with 7 the neutral reading. Readings of less than 7 indicate acid soil, readings above indicate alkaline soil.

Phosphate One of the three major plant nutrients, designated by the letter P.

Photoperiod Length of the light period in a day.

Photoperiodism Effect of differences in length of light period upon plant growth and development.

Pinching Removing the terminal bud or growth to stimulate branching.

Plant Food See Plant Nutrient.

Plant Nutrient Substance or ingredient furnishing nourishment and promoting growth in plants.

Examples: nitrogen, phosphorous, potassium, iron and sulfur supplied by the soil, organic matter and fertilizers.

Plant Residue Plant parts such as stems, leaves, and roots remaining in or on the soil after a crop is harvested.