NALP Horticultural Tech key terms

A geographic rating, based on average annual minimum temperature, that indicates whether a plant is likely to survive winter at a given location. Growers use it to match species to local climate.

The localized conditions of light, temperature, moisture, and wind in a specific spot, such as a south-facing wall or a low frost pocket. These can differ sharply from the surrounding regional climate.

The compass direction a slope or planting bed faces, which governs how much sun and heat it receives. South- and west-facing sites are hotter and drier than north- and east-facing ones.

A plant variety selected and maintained by humans for desirable traits such as color, form, or disease resistance. Its name is written in single quotes after the genus and species, as in Acer rubrum 'October Glory'.

The standardized system of naming plants by genus and specific epithet in Latin, italicized with the genus capitalized. Consistent naming prevents confusion caused by common names that vary by region.

The taxonomic rank grouping closely related species that share structural characteristics. It is the first word of a scientific plant name, capitalized and italicized, such as Quercus for oaks.

Describes woody plants that shed their leaves seasonally, usually in autumn. Loss of foliage reduces transpiration and allows the plant to survive cold or dry dormancy periods.

Describes plants that retain functional foliage through the year, replacing leaves gradually rather than all at once. Evergreens provide year-round screening and winter structure in landscapes.

A period of suspended or greatly slowed growth in plants, triggered by cold, drought, or day length. Pruning, fertilizing, and transplanting decisions depend on whether a plant is actively growing.

A pre-treatment that exposes seeds to cool, moist conditions for weeks to months, mimicking winter. It breaks seed dormancy so germination occurs uniformly when warmth returns.

The mechanical or chemical abrasion of a hard seed coat to let water enter and trigger germination. It is used on species with impermeable seeds such as many legumes and some trees.

The resumption of growth in a seed, beginning with water uptake and ending with emergence of the radicle. It requires adequate moisture, oxygen, and a suitable temperature range.

A measure of soil acidity or alkalinity on a 0 to 14 scale, with 7 neutral. It strongly controls nutrient availability, so pH testing guides lime or sulfur applications.

The ability of soil particles, especially clay and organic matter, to hold positively charged nutrient ions and release them to roots. Higher capacity generally means greater nutrient retention and less leaching.

One of the elements plants need in relatively large amounts: nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Fertilizer labels state the first three as N-P-K percentages.

A layer of organic or inorganic material spread over the soil surface. It conserves moisture, moderates soil temperature, suppresses weeds, and improves soil as organic types decompose.

The widened area where the trunk transitions into the major roots at the soil line. It must remain visible after planting; burying it invites girdling roots and decay.

The vertical projection of a tree's outermost branches onto the ground, often used as a rough guide for root spread. Irrigation and protection zones are commonly extended to or beyond it.

The temporary decline in growth and vigor after a plant is moved, caused by root loss and disrupted water uptake. Proper timing, root-ball handling, and watering reduce its severity.

The selective removal of plant parts to improve structure, health, safety, or form. Correct cuts and timing vary by species and growth habit.

The slightly swollen tissue at the base of a branch where it joins the trunk. Cutting just outside it preserves the tree's natural defense zone and speeds wound closure.

A pruning cut that removes a branch back to its point of origin or to a lateral branch, without leaving a stub. It improves light penetration and reduces crowding without stimulating dense regrowth.

The height at which turfgrass is cut, measured from the soil surface to the blade tips. Each species has a recommended range; cutting too short weakens roots and invites weeds.

The guideline that no more than one-third of the grass blade height should be removed in a single mowing. Following it keeps turf dense and healthy and reduces clipping accumulation.

Cutting turf so short that stems and crowns are exposed and large amounts of leaf area are lost. It stresses grass, thins the stand, and opens ground for weed invasion.

A tightly intermingled layer of dead and living stems, roots, and shoots between the green turf and the soil surface. Excessive thatch blocks water and air movement and harbors pests.

The mechanical removal of soil cores or the creation of channels to relieve compaction and improve air, water, and nutrient movement into the root zone. It is a core cultural practice on high-traffic turf.

The compression of soil particles that reduces pore space and restricts root growth, water infiltration, and oxygen supply. Traffic and heavy equipment are common causes in lawns and landscapes.

A non-grass plant with two seed leaves and typically net-veined, broad foliage, such as dandelion or plantain. It is managed differently from grassy weeds and often with selective herbicides.

A product applied before weed seeds germinate, forming a barrier in the soil that prevents seedling establishment. Timing and correct incorporation are critical because it does not control existing weeds.

A decision-making approach that combines cultural, biological, mechanical, and chemical controls, using pesticides only when monitoring shows they are needed. It reduces resistance, cost, and environmental risk.

The clothing and gear worn to reduce exposure to hazards, such as gloves, eye protection, hearing protection, boots, and respirators. It is selected based on the task and the label requirements of the product used.

The legally binding directions and warnings supplied with a pesticide product. It specifies approved uses, rates, protective equipment, re-entry intervals, and storage and disposal requirements.

The minimum time that must pass after a pesticide application before people may enter the treated area without protective equipment. It is stated on the product label and must be enforced.

The splined shaft on a tractor that transfers engine power to attached implements. Its rotating driveline is a severe entanglement hazard, so shields and master guards must stay in place.

A reinforced frame or cab built to protect the operator if a tractor overturns. It is effective only when used with a fastened seat belt and is required on many machines.

The setting that determines how much leaf blade remains after mowing, expressed in inches or millimeters. Matching it to grass species and season is central to turf health.