By Marcia Kirinus, NC State Extension Master Gardener^SM volunteer

It’s seed catalog season and the mailman delivers a daily dose of gardening possibilities every day. It’s easy to be captivated by the beautiful photos and persuasive copy but good catalogs give you more than pretty pictures.  They offer a wealth of information that can help you decide if a plant is right for you. 

To help you get through some of the plant jargon, we’ve compiled a glossary of terms commonly found in reputable seed catalogs. Hopefully it can help you simplify your decision-making process, and empower you to garden with confidence.

USDA plant hardiness zone

The first thing you need to know is your plant hardiness zone. This will tell you the first and last average frost date in a given area. In Durham, NC we are in zone 8a. 

Terms on when to plant seeds:

• Last Frost Date: The last day you expect to see a frost. This is an average taken from the last 10 years. In Durham, NC it is April 5. Many seed starting calculators are based on sowing or planting a certain number of weeks after or before the last frost date.
• First Frost Date: The first day in the fall that you would expect to see a frost. In Durham, NC it is October 30.

Common terms in seed catalogs

• Annual: A plant that germinates, blooms, and dies within one growing season.
• Biennial: A plant that takes two years to complete its life cycle. The first year it will send down roots and vegetative growth and the second year it will flower and set seed. 
• Perennial: A plant that will live more then two years and usually many many years.
• Tender perennial:  A plant that could live year after year unless it is exposed to sufficiently cold winter weather.
• Variety:  A variety is a version of a plant. Each variety has different characteristics such as size, shape, color, time to maturity, or pest and disease resistance. A stable, naturally occurring variation of a population of plants that is within a species. Variety traits are passed on consistently to offspring without outside interference.
• Cultivar:   Many people, myself included, use the term variety and cultivar interchangeably, it’s not right but common. if the specific strain of plant requires human help to keep it pure and consistent, it’s a cultivar, not a variety. 
• Cultivar Group: A broader group of plants with the same genus and species name but they are different. Think of Brassica oleracea. It is the name for cabbage, broccoli, cauliflower, kale, Brussel sprouts, collard greens. Each major group gets its own cultivar group name. 
• Viability or Germination Rate: Expressed as a percentage. It tells you how many seeds will sprout and survive in your packet if used within the expiration date. A seeds viability will decrease with time.
• Days to maturity: The number of days to harvest your fruit, vegetable, flower. This is an average and not an exact number. It does not mean how many days it takes for a plant to mature. 
• Determinate plants: This term refers to the growth habit of a tomato plant. Plants will grow to a fixed, determined size, ceasing growth after flowering. The fruit will set all at the same time within a short period of time (usually about two weeks or so). These plants are ideal for small spaces and container gardening.
• Indeterminate plants: This term also refers to the growth habit of a tomato plant. These Plants continue to grow and set fruit throughout the growing season until killed by frost. These plants are vining and will need a trellis system.
• Semi-determinate: A tomato that is something in-between determinate and indeterminate. It will set most of its fruit all at once. 
• Parthenocarpic: A plant that does not require pollination to set fruit. These plants can bare seedless fruit. Certain varieties of tomatoes, eggplant, cucumbers, summer squash, and watermelon fall in this category.
• Gynoecious: A plant that produces only female flowers. This plant will need a pollenizer to produce fruit.
• Monoecious: A plant that will have both male and female flowers.

Terms of seed types

• Open pollinated (OP) : These plants are pollinated by another plant, as opposed to pollinating itself. These are varieties that will come from true seed, look for the OP symbol if you want to save seeds for future plantings.
• Heirloom: A recognized, open-pollinated variety with a long heritage. There isn’t one agreed upon definition of “heirloom” but typically they are passed down through many years. They tend to have a unique flavor, taste and color. These plants have poor disease resistance when compared to hybrids, and yield is unpredictable.
• Hybrid: Seed or plant from a cross of two or more known species. Saving seed from these plants will not produce plants identical to the parent.
• F1 hybrid: Breeding term for the first generation offspring. Seeds saved from an F1 hybrid will not produce plants with characteristics equivalent to the F1 hybrid. 
• Disease resistant: Implies that a variety has a certain amount of resistance when exposed to a disease-causing pathogen such as a fungus, bacteria, or a virus. Disease resistance is often expressed with abbreviations, for example “V” for Verticillium Wilt. The abbreviations should be explained within the catalog. Catalogs might also display symbols for high resistance to disease (HR) or intermediate resistance (IR). 
• GMO:  (Genetically modified organism) Seeds that have been altered using various genetic engineering techniques. As far as I know, there are no GMO seeds offered to home gardeners, only to the commercial trade.  
• Organic: Sometimes denoted as (OG), organic seeds differ from conventional seeds in that they’re grown under regulated organic growing conditions stipulated by the seed farmers’ certifying agency (typically the USDA or CCOF).
• Biodynamic seeds: These types of seeds are certified by the Demeter Association (similar to how organic seeds are certified by USDA). Biodynamic seeds are open-pollinated varieties grown on farms adhering to strict guidelines about germination rates and following all biodynamic gardening principles (including no pesticide use and no complex treatment in labs).

Terms on seed requirement:

• Requires light:   Some seeds will germinate better if exposed to light. Many flower seeds like poppy, Papaver sp. require light for strong germination.
• Requires stratification:  Subjecting the seed to cold in order to break dormancy and promote germination. Typically, it refers to simulating a winter dormancy period by exposing seeds to cold for a period of time.
• Requires scarification:  Seeds which must have their hard outer layer damaged in a controlled way before germination will occur. This involves scratching, sanding, or nicking the seed coat. It’s also possible to treat the seed with a dilute acid or alkaline solution to soften the seed coat.
• Requires vernalization:  The process of exposing seeds, seedlings or young plants to cold temperatures for a specific length of time to stimulate flowering.

Terms on seed enhancement:

• Treated: The seeds are coated with fungicides or insecticides to protect them from disease and pests during their germination and seedling growth. It is common for companies to add color to these seeds to be able to differentiate them from untreated seeds.
• Pelleted seeds: Pelleted seeds are small, irregularly shaped, hard-to-handle seeds that have been coated with an inert clay to make them larger, more uniform in shape, and easier to see and sow.   Tiny seeds like carrots, onions, and lettuce are often pelleted.
• Priming:  A process used to speed up germination time. Many lettuce seeds, for example, are primed to germinate quickly. This process will shorten the shelf life of the seeds.

Resources and Additional Information:

• USDA Cold Hardy Zone designation and the Horticultural Society’s Heat Zone designation: Two Tools That Help You Garden Smarter
• Sowing seeds directly in the garden in autumn: Ten Tips for Direct Sowing Cool Season Spring Flowers. Start Now!
• When to plant cool season annuals: Starting Cool-Season Annuals for Early Spring Blossoms
• North Carolina Extension Gardenres Handbook, Glossary of terms: https://content.ces.ncsu.edu/extension-gardener-handbook/glossary

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