Seed and plant catalogs wing your way to your door and pop up on your screen. Garden centers are full of displays of seed packets of all kinds. It’s so exciting! You dive in and try to pick out the very best plants for your use. But the vocabulary found on the back of seed packs and in printed and virtual seed catalogs can be arcane, even confusing. For many beginners, it’s like reading a foreign language! To help you, here are a few terms you may encounter and their definitions.
Acclimatization: A vital action taken just before transplanting seedlings outdoors. It simply means to place the seedlings, still in their pots, outdoors in the shade for 2 or 3 days, then in partial shade for 2 or 3 days, then in full sun for 2 or 3 days. The seedlings are now “hardened off” and ready to transplant to their permanent location.
Annual: a plant that completes its life cycle, from germinating to seed production, in one single year, then dies. Ex.: cosmos, marigold, sunflower.
Hardy Annual: an annual that tolerates cool soil and even a bit of frost. It is usually sown directly in the garden, early in the spring. Ex.: spinach, sunflower.
Half-Hardy Annual: an annual that tolerates could soil, but not frost. It is usually sown indoors in short-season or cool climates, but directly outdoors in warmer ones, as soon as there is no risk of frost. Ex.: cosmos, lettuce, petunia.
Tender annual: a plant grown as an annual that needs constant warmth and will not take frost. In all but tropical climates, it is generally started indoors and transplanted into the garden when both the soil and air have warmed up and there is no risk of frost. Ex.: basil, begonia, tomato.
Biennial: a plant that completes its life cycle in two years, usually producing a rosette of leaves the first year and flowers and seed the second. It dies after seed production. Ex.: foxglove, parsley.
Perennial: a herbaceous plant (not woody) that lives more than two years and that blooms more than once. It does not die after flowering.
Botanical Name: see Scientific Name.
Bush-type: see Non-Running.
Chlorosis: when leaves contain insufficient chlorophyll. They are often pale, yellow, or yellow-white. An iron deficiency, or lack of iron, is a common cause of chlorosis. See Nutrient Deficiency.
Cold Treatment (Stratification, Vernalization): subjecting to cold temperatures seeds that need to go through a cold period before germinating. Usually they are sown in pots of moist soil and placed in a refrigerator for several weeks before exposing them to heat. An alternative is to sow them outdoors in the fall in a cold climate where they will naturally undergo cold temperatures. Many perennials, shrubs, and trees from temperate climates require a cold treatment.
Cotyledon: a seed’s first leaf, usually simple and often very different in appearance from mature leaves. Most seedlings have two cotyledons, but there are seedlings with only one cotyledon, more than 2 cotyledons and without any cotyledon.
Cross-Pollination: The transfer of pollen from the anther of a flower of one plant to the stigma of a flower of another plant of the same species. It is usually carried out by insects, birds or wind.
Cultivar: a plant raised and multiplied by humans, that does not exist in nature. Its name is typically written between single quotes (‘ ‘). The name derives from “cultivated variety.” Ex.: in Cosmos bipinnatus ‘Sonata White’, ‘Sonata White’ is the cultivar name.
Determinate: said of a tomato plant (and a few other plants) in which each branch ends in a cluster of flowers, which therefore limits its upward growth. Determinate tomatoes make fairly small plants and don’t always need staking. They tend to produce all their tomatoes at about the same time.
Indeterminate: said of a tomato plant (and a few other plants) whose flowers appear in the axils of branches and not at the stem tip. Therefore the stem continues to grow in height throughout the growing season. These tomatoes need staking or a large tomato cage. They may produce less fruit at once than a determinate tomato, but usually do so over a long harvest season and often give double or triple the yield of a determinate tomato.
Dioecious: refers to a plant whose male and female flowers are borne on different plants. The asparagus is dioecious.
Monoecious: refers to a plant that produces separate male flowers and female flowers on the same plant. Often the female flower is easily recognized because it has a small ovary at its base in the shape of the fruit to come. Squash, melons and cucumbers are monoecious.
Perfect Flower (Bisexual Flower, Hermaphroditic Flower): said of a flower that has both male and female organs, thus both a stigma and stamens. This is the most common situation in nature.
Direct Sowing (Direct Seeding): sowing a plant directly outdoors where it is to grow. Beans, marigolds, and corn are often direct sown.
Do not cover: said of a seed that should not be covered with soil at sowing, usually because it is either very fine or requires light to germinate, or both.
GMO: genetically modified organism. Said of a plant into which humans have inserted genetic material from another plant or even an animal without going through pollination. There is, for example, corn containing the genes of Bt (a bacterium) and varieties of canola and soybean which with inserted genes that make them resistant to herbicides. At the time of writing this, there are no GMO seeds or plants available to home gardeners.
Hardening Off: see Acclimatization.
Heirloom Vegetable (Heirloom Plant): an old variety. Some authorities consider a plant having been introduced more than 50 years ago to be an heirloom variety, others prefer the definition “before the 1940s.” Most heirloom vegetables are produced through open pollination, that is pollination carried out by insects, birds, or wind. Examples.: ‘Brandywine’ tomato, ‘Golden Bantam’ corn, etc.
Hybrid: plant resulting from the crossing of two different breeds, species or genera. F1 hybrids are the most common type of hybrid and are the result of a first-generation cross (F1 means “1st filial generation”). Usually, F1 hybrids are more robust than non-hybrid plants, but more expensive, because they have to be manually pollinated in a greenhouse setting. F2 hybrids, less common on the market, are seeds of F1 hybrids, thus the second generation (2nd filial generation). They are cheaper, as they are generally produced by natural pollination, but tend to give less reliable results than F1 hybrids.
Last Frost Date: see Spring Frost-Free Date
Latin Name: see Scientific Name.
Nutrient Deficiency: results from the lack of a vital mineral in the soil (phosphorus, potash, nitrogen, zinc, boron, iron, etc.). It can have various symptoms include discolored or deformed leaves or slow growth. Treatment with a complete fertilizer (containing all the trace elements, such as a seaweed or fish fertilizer) will usually overcome a deficiency.
Organic: various definitions. Organic seeds are harvested from plants that have not been treated with synthetic (that is to say, chemical) pesticides or fertilizers. Organic pesticides and fertilizers are derived from natural sources, not from chemical synthesis.
Peat Pot: pot made of pressed peat, coir or other organic materials, usually used for seedlings that will not tolerate transplanting. The peat pot allows roots to grow right through its sides and bottom and can therefore be transplanted into the garden without removing it. The roots of the plant will then grow right through the peat pot into the surrounding soil.
Pelleted Seed, Seed Pellets: seeds covered in a product (usually clay) which facilitates their handling.
Multi-pellets: seed pellets that include several seeds and are used for plants that look best when grown in a clump, such as bedding lobelias.
Pinching: removal of a plant’s terminal bud (bud at the end of the stem). Pinching stimulates branching, giving a more compact and attractive plant, but may delay flowering. It is traditionally done by “pinching” the top growth between the thumb and forefinger, but can also be done using pruning shears or scissors.
Requires Light to Germinate: said of a seed that germinates only in presence of light, be it sunlight or artificial lighting. These seeds should be sown without covering them with soil and the pot should be placed in a brightly lit spot.
Running: said of a squash with long creeping stems that require a lot of space in the garden, like a pumpkin. This is the natural state for squash.
Non-Running (bush type): said of a squash that produces a short stem and a rosette, taking up less space in the garden than a running squash. The zucchini is the best known non-running squash.
Scarification: action of filing, nicking, or cutting a seed before sowing it. It can also involve soaking it for several hours in warm water. The goal of scarification is to penetrate very hard seeds (morning glories, hibiscus, etc.) and thus accelerate their germination.
Scientific Name (Botanical Name, Latin Name): it consists of two words, the first being the genus name (name shared with related plants, much like a human surname) and the second, the specific name, which determines the plant accurately. For example, Solanum tuberosum is the scientific name of the potato and Solanum melongena, of the eggplant. Both share the same genus name, Solanum, because they are closely related, while the specific name serves to make it clear to which type of Solanum the writer or speaker is referring. The scientific name is usually written in italics when possible.
Self-fertile: refers to a plant whose flowers can self-pollinate, that is to say that its own pollen can ensure seed production. Most plants are self-fertile.
Self-sterile: said of a plant which has to be pollinated by another variety in order to produce seeds. Many fruits (apples, pears, plums, cherries, etc.) are self-sterile or partially self-sterile. In their case, it is always best to cultivate at least two cultivars of the same species nearby, as cross-pollination is necessary for them to produce abundant fruits.
Spring Frost-Free Date: the date used in calculating when to start tender plants indoors, referring to the approximate date when you can expect there is no longer any risk of spring frost, usually about 2 to 3 weeks later than the average last frost date. (About one year out of two, there will be frost after the last average last frost date: that’s why it’s an average.) On seed packs and in seed catalogs, you’re often told to start seeds indoors so many weeks (6 weeks, 8 weeks, etc.) before the spring frost-free date. You can ask a local garden club or garden center for the last frost date in your region, then simply count backwards to find the right date for sowing seeds.
Stratification: see Cold Treatment.
Thinning: removing some seedlings or fruits in order to allow room for others to grow better. Usually this is done by cutting the excess plants or fruit stalks the base.
Transplanting: moving a plant from one place to another. In the case of seedlings, this is usually from the pot in which they were sown into a larger pot or into the ground.
Treated seed: seed has been treated with a fungicide to prevent rot in cold or wet soils. This treatment is not considered acceptable to organic gardeners.
Untreated Seed: seeds that have not been treated with fungicides and therefore acceptable in organic gardening.
Vernalization: see Cold Treatment. It can also mean subjecting growing plants to cold in order to stimulate flowering.