4. HORTICULTURE TERMS: F1 Hybrid, Open-Pollinated & Heirloom, Variety & Cultivar Plant Definitions: Annual, Biennial And Perennial Definitions, Horticulture Terms – F1 Hybrid, Open- Pollinated And Heirloom, Variety And Cultivar, Plant Definitions: Annual, Biennial And Perennial Landscaping Terms

F1 Hybrid, Open-Pollinated & Heirloom

Choosing plant varieties can be challenging; however, understanding certain horticulture terms can go a long way to helping you choose just the right plants for your needs. You may have seen terms like F1 hybrid or cultivar and wondered just what they mean. Here's a rundown of some common terms.

F1 Hybrid

Sometimes simply referred to as hybrids, these plants are created by plant breeders to enhance certain traits, such as improved hardiness, larger flowers, tastier fruit, or better disease-resistance. To create an F1 hybrid, breeders start by repeatedly inbreeding plants into two genetically stable strains. Then they cross-pollinate the two strains. The offspring are referred to as F1 hybrids.

Why this is important: If a certain plant disease is prevalent in your area, there may be a disease-resistant hybrid. For example, Early Girl is an F1 hybrid tomato that is resistant to several common diseases.

F1 hybrids don’t grow "true to type" — that is, if you save and plant the seeds, the resulting plant may not have the desirable traits of the parent. If you want to save seeds, choose non-hybrid plants.

Open-Pollinated OP

If a plant isn't a hybrid, it's described as open-pollinated (OP). (Note that if a plant isn’t labeled as a hybrid, you can assume it’s OP.) In nature, these plants are usually pollinated by insects or the wind. Because the flow of pollen is unrestricted, OP plants have lots of genetic diversity.

Why this is important: Genetic diversity allows plant populations to adapt to local growing conditions and ecosystems.

OP plants grow true to type — that is, if you save seeds for replanting, the offspring will similar (though not identical) to the parent plants.

OP seeds are often less expensive than hybrid seeds. These seed packets tell you that these are open-pollinated and heirloom varieties.


Horticulturists differ on how they define the term heirloom. Many people consider a plant an heirloom if it is open-pollinated (non-hybrid) and has been around for at least 50 years. Others say it must have a record of being handed down generation to generation.

Why this is important: Varieties handed down over generations can adapt to thrive in the conditions of a specific locale. Some people think heirloom varieties are tastier. Because they’re open-pollinated, you can save seed for replanting year after year.

Some heirlooms are more susceptible to diseases than their hybrid kin that have been bred for disease resistance.

Variety and Cultivar

A variety is a form of a species that is slightly different than the "regular" species, but not different enough to warrant a new species. Varieties are often found in nature, as opposed to being created by plant breeders.

The term cultivar is shorthand for cultivated varieties and refers to plants that have been developed by plant breeders or discovered growing in nature and propagated by horticulturists. The plants are often propagated vegetatively, such as by rooting cuttings.

Why this is important: Many commonly available plants are varieties or cultivars, with interesting features that make them more desirable than the straight species. Some cultivars are patented, making it illegal to propagate them yourself. The plant name may bear a trademark symbol, and you may see a warning that propagation is prohibited.


Theophrastus (about 370-285 B.C.) is often called the "Father of Botany." He was the first person to publish an organized classification of plant. He was a Greek philosopher and naturalist, and a pupil of Aristotle.

ANNUALS are plants that go through their entire lifecycle in one growing season. They are sown outside in April and May and can survive/withstand light frost. An example is Calendula officinalis, which I grow in my community garden.

Technically, all annual plants are herbaceous, because an annual is a non-woody plant. Annuals take it a step further and die altogether at the end of their lone growing season, both above the ground and below it. Annuals provide vegetative growth, flower set, and seed production in one growing season.

A good many gardeners rely on annuals to fill patio pots and window boxes, but these plants, which give their all in a single season, are also superb for bedding. Mounds of Impatiens and Coleus create colorful mosaics in shade gardens while drifts of Nicotiana, Cleome, Zinnias and other favorites add spark and pollinator attractions to sunny borders.

One general rule of garden design is that many plants, including a great number of annuals, are best planted in groups of 3’s and 5’s. In borders and beds, these groupings create mass and a sense of intention, qualities that help make a garden appear to have been designed. If space allows, consider repeating same-plant groupings to create a visual rhythm and a unifying theme in the garden.

Again, annuals last only one season, dying away after autumn’s first hard frost. While this typically makes us momentarily wistful each fall, the joy comes in spring when we can choose new varieties to plant and rediscover old favorites.

BIENNIALS are plants whose lifecycle spans two years, so they flower and produce seeds in their second year. A familiar biennial is foxglove, Digitalis purpurea. Some plants grown as biennials are, botanically speaking, short-lived perennials, for example, sweet William and wallflower. These plants tend to be dug up after flowering simply because they don’t perform well the following year, or become too untidy.

Again, a biennial is a plant that completes its life cycle in two growing seasons, i.e., leaves are formed the first season followed in the second season by flower set and seed production. Hollyhocks are an example.

Biennials lack woody stems, therefore they can be characterized as herbaceous as they drop seed and the plants come back in the summer. However, biennials such as foxglove (Digitalis) and silver dollar plant (Lunaria) maintain live, low-growing foliage above-ground during the winter (known as "basal leaves"). Thus the question of whether a plant is herbaceous or not hinges on the presence or absence of woody stems, not on winter die-back.

PERENNIALS are plants that perpetuate itself for long periods of time usually growing from modified underground stems. They are plants that can survive frost and live for more than two years.

Tender perennials live more than two years. They cannot survive cold frosts. Tender perennials need to be in a frost-free environment over winter or put outside when the danger of frost has passed.

Herbaceous perennials have non-woody stems. Their above-ground growth largely or totally dies back in winter in the temperate zone, but they may have underground plant parts (roots, bulbs, etc.) that survive and re-emerge in the spring and summer.

While some perennials are evergreen, for Northerners, "perennials" and "herbaceous perennials" are almost synonymous.

Perennials in general are non-woody plants that die back to around ground level once cold temperatures return. They do, however, survive the winter, thanks to their underground plant parts. This group includes some of the most cherished plants in the landscape including the following examples:

Columbine (Aquilegia)

Montauk daisies (Nipponanthemum nipponicum)

Larkspur (Delphinium)

Hardy mums (Chrysanthemum)

Peonies (Paeonia lactiflora)


Garden phlox (Phlox paniculata)

Stonecrop (Sedum)

Oriental poppies (Papaver orientale)

Herbaceous plants and bulbs also include annuals and biennials. Some common bulbs are Daffodils, Narcissus, Dahlias and Gladiolus.

When people speak of "herbaceous" plants, they usually limit the discussion to perennials even though there are annuals and biennials that are herbaceous.

Woody perennials are plants that maintain live woody stem grow at the end of the growing season, i.e. exhibiting secondary growth. e.g. lilac, Syringa vulgaris.

Perennials are exceptionally generous plants. Plant them once, and they return year after year, creating beautiful and bountiful displays of blossoms and foliage. Established perennials ask for little in return: regular watering, a bit of mulch, and the occasional end-of-season haircut. It’s no wonder that experienced gardeners rely on these beloved plants for color, texture and low-maintenance beauty in their gardens.

When choosing perennials, remember that garden designers almost always recommend planting in multiples of 3 or 5. These groupings create the appearance of mass, increasing the impact of each individual plant and subtly conveying the look of a designed garden. If you have adequate space in your borders, repeat groupings at regular intervals. There is no better way to create a visual rhythm and to foster a sense of unity and cohesion in your garden. Order now for best selection. Your perennials will be shipped at the proper time for planting in your area.

Herbaceous perennials have non-woody stems. Their above-ground growth largely or totally dies back in winter in the temperate zone, but they may have underground plant parts (roots, bulbs, etc.) that survive and re-emerge in the spring and summer.

While some perennials are evergreen, for Northerners, "perennials" and "herbaceous perennials" are almost synonymous.


Border - a garden border is an area that is open in front and backed by a structure, such as a house, fence, hedge or patio. Borders are a narrow strip of landscaping which surrounds a larger landscaped feature like a path or lawn.

Cottage gardening - gardens based on an English style of gardening in which many plants are placed in a dense and seemingly random fashion. More formal designs also known as symmetrical design involves a planting design with geometric shapes and straight lines. These are the more modern gardens.

Foundation planting - a group of plants used in landscape design to blend with a home within its setting and obscure any undesirable features of the foundation. Examples: Shrubs or trees. They should not look too large or overgrown.

Herbaceous and Woody Plants - a herbaceous plant has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent wood stems above ground. Herbaceous plants may be annuals, biennials or perennials. Non-herbaceous perennial plants are woody plants that have stems above the ground that remain alive during the dormant season and grow shoots he next year from the above-ground parts including trees, shrubs and vines.

Perennials - These plants usually live for more than two years, and can are distinguished from short lived annuals and biennials. They have little or no woody growth from trees and shrubs, which are technically perennials. Perennials, especially small flowering plants, that grow and bloom over the spring and summer, die back every year fall and winter, and then return in the spring from their rootstock. These are known as herbaceous perennials.

Perennials, annuals, and shrubs do well as border plants, as they last two or more years with care. A good border plant is dense and compact like Sweet Willian, a dianthus. Some shade border plants include lady's mantle, impatiens, dianthus and hostas (front of border) - astilbe and hydrangea shrubs (back of border). Some sun-loving border plants include lamb's ears, pansy, petunia, sweet alyssum, and snapdragons (front of border) - lantana viburnum shrub, forsythia shrubs, hollyhocks and gladiolus (back of border). A mixed border includes a combination of different types of plants such as annuals, bulbs, perennials and shrubs.

Naturalized - to plant randomly and without a pattern.

Ornamental - Plants grown for aesthetics, not consumption or

economic use.

Specimen Plant - plants grown by themselves in a lawn or garden for an ornamental effect, rather than being massed with other bedding or edging plants. Specimen plants serve as focal points in landscape design.

Specimen Trees - the definition varies from gardener to gardener. Some consider especially old trees as specimen trees. Others believe that trees with exceptional beauty are the ones that stand out as specimen trees. Still others consider trees that have reached a certain height. In Vermont, the large sugar maples and weeping willows stand out. There are some sycamore's, a rare tree in Vermont that stand tall in Putney and a particular silver poplar that grows large at Knoll Farm in Waitsfield. It takes four people with long arms to wrap around the circumference of the tree.

Terracing - creating one or a series of level areas on a sloped site. Terracing sometimes involves building retaining walls to hold soil in place.

Understory Trees - a term for the area of a forest which grows at the lowest height level below the forest canopy. Plants in the understory consist of a mixture of seedling and saplings of canopy trees together with understory trees, such as moosewood striped maple, mountain maple), shrubs and herbs. Some dogwoods are understory trees.

Variety and Cultivar

Although the terms "variety" and "cultivar" are often used interchangeably, they are different. The technical difference is that a true variety is found growing in the wild, like the common chokeberry while a cultivar is grown in cultivated gardens.

A cultivar is a plant or groupings of plants selected for desirable characteristics that can maintained by clonal propagation. Popular ornamental garden plants are roses, daffodils, rhododendrons and azaleas. They are produced by careful breeding and selection. Similarly, the world's agricultural crops are almost exclusively cultivars that have been selected for improved yield, flavor and resistance to disease.

When a plant exists in cultivation and propagated to maintain its particular characteristics, it is a clone, but when given a name is called a cultivar. The word "cultivar" was formed by linking the words "cultivated" and "variety". Almost all the plants we grow in our yards and gardens are cultivars, but not if grown from a seed. With all that being said, I will use the word "variety" in most cases as this is the word most folks are familiar with.