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Understanding Flowering Plants
Four Categories of Flowering Plants
Gardeners learn flowering plant lifecycles and know how to use each type of flowering plant in their landscape gardens.
Here, we’ll discuss the use of annuals, biennials and perennial flowers in home landscapes, gardens, beds, borders, and containers.
You’ll find a similar discussion of the much more varied use of flowering bulbs on the following page [see: Bulbs and Seasons of Bloom]
Annuals and Tender Perennials
Annual Flowering Plants
Most gardeners treat true annual flowers and tender perennials that are sensitive to frost and die in long periods of cold or freezing temperatures the same when they plant them in flower gardens.
True annual flowers grow each year from seed, develop flowers, become ripe and are pollinated, and produce new seed before dying. The cycle repeats each year, maintaining each annual species.
This makes them ideal as colorful bedding plants to add variation and change to home landscape plantings.
Gardeners use both annuals and tender perennials primarily as bedding plants.
Those that garden in cold-winter areas—and many other gardeners—prefer to extend their seasons by starting their bedding plant as seeds sown indoors in bedding trays, flats, or containers.
Starting seeds early gives every gardener the widest choice of exact species, varieties, and cultivars of annual plants and tender perennials.
This activity typically begins long before snows and cold weather are over [see: Planting Flowers into Containers].
You’ll also find our how-to demonstration of Starting Flowers from Seed here, with step-by-step photos and clear instructions.
Others prefer to obtain their plants from garden stores, relying on nursery growers with hot houses or greenhouses to take care of planting seed and caring for seedlings.
Many plant choices are available each year for a few weeks at spring, but once the season advances and weather warms, selection may become spotty.
Regardless of your choice of source, once you transplant annual and tender perennial seedlings into your garden’s containers, beds, or borders, they will thrive.
Annuals are in a hurry, compared to most other flowers. They have just one or two chances each season to complete their life cycles. They rush to develop shoots, stems, and foliage. Before the leaves unfurl, nascent—developing—flower buds begin to show.
Within a few weeks, your landscape is covered with beautiful flowers and buzzing bees gathering and spreading pollen. Your enjoyment begins.
Keep the joy coming with simple care [see: Controlling Growth and Flowering].
End of Bloom
All good things must end, however. Eventually, the ripe and pollinated flowers set seed and plants begin to die.
Most gardeners choose this time to remove the dying annuals and replant their beds, repeating the cycle for a succession of new flowers for summer, late summer or early autumn.
Others let their plants complete their life cycles, gather their seeds for the following year, and then replant or let nature take its course [see: Collecting and Saving Flower Seeds].
Annual flower gardening is fun, simple, economical, and easy.
Biennials and Perennials
Biennial Plants
Biennials are a second group of flowering plants that, like annuals, have short lives.
The life cycles of biennial flowering plants last two years: a first year to develop foliage and mature roots—sometimes with a few, sparse flowers —and a second year to mature, set their flowers and produce seed.
Because they frequently bear unusual or striking flowers, biennial plants often provide eye-catching features for flower gardens, making them showpieces that gather admiring comments.
Most gardeners choose to skip planting seed or waiting a full season to see the results of their efforts.
They instead buy their biennial flowering plants from garden centers. Growers rear these two-year plants through their first season, then move them into stores in time for their big show.
Gardeners transplant the nursery-grown biennials into their own containers, beds, and borders.
For this reason, biennials are mostly used by gardeners in the same ways as they do all the true annuals and tender perennials—for spot color and for bedding plants.
Perennial Plants
Perennials, to compare with annuals and biennials, are long-lasting plants, living from year to year.
They are classified as hardy, half-hardy, or tender based on their tolerance for cold temperatures. Many consider tender perennials interchangeable with annuals, and those who garden in cold-winter climates focus only on the hardy perennials
Because perennials may live for many years in your flower garden, they are sometimes referred to as “foundation plants.”
This term means you’ll enjoy their floral display each season, often becoming more attractive as the years pass by, with only minimal care required.
For this reason, gardeners choose perennials for their flower gardens with care. Most transplant perennials grown by nurseries in containers into their gardens [see: Planting Flowers Outdoors and Planting Flowers in Containers].
These transplants received optimum care from quality growers, are well nourished, and are free from defects, pests, or weeds. They’re ready to take center stage in your landscape.
Once transplanted, provide them tender care for their first month or so [see: After-Planting Care].
For the longer term, care for perennials as directed [see: Caring for Flowers].
You’ll also find care directions tailored to each species in the Care tab of each of our perennial plant guides.
Step-By-Step Instructions
Growing annuals, biennials, and perennial plants from seed indoors is an easy way to add many days to your gardening season and time to enjoy flowers in your landscape containers, beds, and borders.
Sowing seed indoors is also economical. A package of seed usually contains dozens of seeds and costs less than a single nursery-grown container plant.
Gather your seed, bedding trays, potting soil, implements, and other materials and follow these simple steps:
Starting Flowers from Seed
Clean a bedding tray and tools with a mixture of 1 part household bleach to 9 parts water. Fill tray with potting soil. Open furrows in parallel rows or space planting holes a 4 in. (10 cm) intervals.
Carefully tap seeds from the seed package into each of the prepared rows, spacing the seeds as recommended by the seed supplier.
Close the furrow or hole or sift soil over each seed, burying the seed to the depth recommended on the seed package.
Press the soil with your palms until it is firm. Good soil contact is essential to germination.
Apply water by misting the soil in the tray. Avoid over saturating the soil. Cover the bedding tray. Seeds will germinate.
Inspect and recover the flat daily, adding water as needed. Install supports to keep cover from touching the foliage of sprouting seeds.
Seedlings will first develop seed leaves, then true leaves. Transplant them to containers or your garden when they are at least 4 in. (10 cm) tall and before they begin to become crowded.
Transplant before the roots of plants become intertwined.
Warning:
Household bleach contains sodium hypochlorite, a powerful skin and eye irritant. Avoid hazard by wearing gloves and protecting clothing whenever mixing or pouring bleach solution.