The easiest way to think of annuals is to think of them as plants that go from seed to seed in one year or annually.
- You plant the seed (or buy a seedling/or young plant).
- The plant grows and flowers.
- The plant sets seed.
- The plant dies.
The most common annual plants known to most people are the plants you buy at the garden center each spring and early summer. Some plants that come to mind are some common flowers, vegetables, and fruits like tomatoes, peppers, cucumbers, zinnia, cosmos, impatiens, and petunias. Annuals can be further divided into two groups called cool season annuals and warm season annuals.
Cool Season Annuals
Cool season annuals are not new, but they may be unfamiliar. They consist of a group of plants that can handle, and prefer, some degree of cooler temperatures and many are frost tolerant. You may recognize some cool season vegetables like lettuce, peas, and spinach. These plants establish best when cool temperatures, below 70 degrees, are present. Cool season flowers are useful for filling the blooming gap between early season bulbs like tulips and daffodils and warm season annual flowers that are not frost tolerant like Zinnias, Dahlias, and Cosmos. Some hardy annuals like Ornamental Kale, are also useful in the cool fall season.
One cool season annual flower that may be familiar is the Pansy. However, if you want to grow cool season flowers for cutting or just want something different that blooms early in the season, here are a few you may or may not be familiar with:
- Ornamental Kale
- False Queen
- Anne’s Lace
- Sweet Pea
- Love in a Mist
- Bells Of Ireland
- Corn Cockle
Warm Season Annuals
Unlike cool season annuals, warm season annuals are not frost tolerant. Also referred to as tender annuals, they cannot survive and thrive in cold conditions. They are best planted after all danger of frost has passed. For my area of Waterloo, Wisconsin, the hardiness zone is 5b. This has changed in the past 10 years from the former hardiness zone of 5a. Some warm season annuals are:
Biennials are perhaps the most confusing category for many gardeners and plant lovers. Biennials grow only leaves the first year. The second year they flower, set seed, and die. They are useful because they are often flowering between spring bloomers and many summer perennials. One of the most common types of biennials is Foxglove. I have had many customers mention their frustration that their Foxglove didn’t bloom. This is because the plant’s growth cycle was not understood. I grow biennials from seed started in summer, plant small plants in the fall, and get blooms the following spring. You can allow biennials to drop their seed to always have plants that are in each stage of the life cycle. This ensures there are flowers each year. Some annuals act as biennials depending on when they are planted. One example, would be fall planted Poppies. Here are a few biennials I think are worth growing:
- Sweet Rocket
- Iceland Poppies
- Sweet William
- Money Plant
Defined = Plants which maintain a woody structure of branches and stems above ground at all times, these include trees and shrubs.
Defined = A plant whose growth dies down annually, but whose roots or other underground parts survive.
In simple terms, perennials are plants that return each year. Where the confusion can lie is that there is a differentiation between herbaceous and woody perennials. For the sake of simplicity, I am referring to Herbaceous Perennials, those plants that die to the ground and then come back and grow each season. Common herbaceous perennials are Daylily and Hosta. Some of my favorite perennials are:
- False Indigo
- Black Eyed Susan
- Echinacea (Coneflower)
- Gooseneck Loosestrife
Final note: Keep in mind that there is some overlap between annuals, biennials, and perennials depending on the growing situation, varieties used, and intended use. I hope with a basic explanation of annuals, biennials, and perennials, you have gained a better understanding of this somewhat confusing terminology.