The term "annuals" has expanded to include quite a few plants commonly used in the home landscape. Botanically, an annual is a plant that goes from seed to seed in one season and then dies. The plant has no choice, one year and out it goes.

In today's horticulture industry, not all the plants called annuals would fit this definition. In fact, most of them would not. Now, the gardener's definition of an annual is any plant that only survives one year "...IN MY GARDEN". Many of the plants we include in this group are actually herbaceous perennials that live more than two years in their native environment. They are only annuals in other geographic areas because they will not survive the cold or heat and droughty condition in those locales.

So, for this topic we will consider all those plants commonly called annuals regardless of their real intended lifespan.

 
Pros and Cons of Annuals

Annuals have become popular in the landscape because they are easy to grow, have few disease or insect problems and produce flowers from the day they are planted to the first heavy frost in the fall. They are available in a huge number of species and cultivars for nearly every landscape design purpose.

About the only drawbacks are the fact that you must buy new ones every year and you must put in the labor to plant them every spring. Perennial enthusiasts might complain that they are boring since they are the same for the entire season.

Uses of Annuals in the Home Landscape

Annuals have several potential uses in our landscapes including:
  • Beds and Borders - Starting in Victorian times in England, the use of annuals in mass plantings has been popular. Large groupings of individual types and colors can make a striking impact in the garden.
     

  • Containers - Although the whole array of landscape plants can be grown in containers, most gardeners think first of using annuals.
     

  • Cut Flowers - Many types of annuals may be used as cut flowers for display in the house. Some people grow rows of annuals in the vegetable garden specifically for this purpose while others take their flowers randomly from beds and borders.
     

  • As Fillers - Those perennials that are supposed to live "forever" sometimes don't make it through the winter. To fill the void quickly, annuals may be used as a temporary measure to avoid holes in the beds or borders.


As a group, annuals contain a very large variety of site requirements. Most enjoy full sun but some, like impatiens, will thrive in the shade. In general, annuals need a light, well-drained soil with a pH in the slightly acid range of 6.0 to 7.0.


The category of "annuals" include many plants that are really tender perennials that are not harder for cooler climates. Therefore, it is important to pay attention to the proper timing for transplanting them into the garden.

Generally, there are three categories for time of planting:

  1. Hardy Annuals - These are plants that routinely survive frost and cool temperatures. This might include pansies, snap dragons and other cold tolerant plants. The old saying associated with these plants is that you can plant them when the "forsythia are in bloom".
     

  2. Semi-Hardy Annuals - Included in this group are plants that may be planted "when the lilacs are in bloom". They are fairly tough plants that can withstand a slight dip below freezing with little or no damage. Petunias, geraniums (Pelargoniums) and calendulas would represent this group.
     

  3. Tender Annuals - This group of plants generally come from a tropical or subtropical region of the world and cannot stand any frost at all. Plants in this group should not be planted until after the "frost free" date in your area. The most common plants in the group would include impatiens, zinnias and marigolds.

As a rule, annual transplants should be placed in the soil at the same depth as they were growing in the container. In other words, avoid burying the stems too much. Also, if the roots have formed a solid mass, cut or tear this apart before planting so that the roots may spread out from the original root ball.


Perhaps the key to the establishment and top performance of annuals is water. They need to be kept moist from the day they are planted until they die in the fall to get their maximum display. This is especially important for plants in containers.

We expect annuals to flower from the day they are planted to the day a frost kills them. Flowering is a very energy dependent process so annuals need to have nutrients available to them most throughout the growing season. Slow release fertilizers can eliminate the need for constant applications. Liquid fertilizers work well also.

Annuals are often the only types of plants some homeowners use in their landscapes. Therefore, the industry has tried to make them as trouble free as possible. Most commonly grown annuals do not have any serious disease or insect problems.

Plants grown as annuals are in that category because they cannot overwinter in a particular region. Some tender perennials such as geraniums (Pelargoniums) or impatiens can be taken into the house to grow under lights for the winter.

Many of the plant that we grow as "annuals" can be grown from seed. If you plant them in the garden in the spring when the soil is warm enough for germination, it will be late summer before most of them flower.

You can start your own seeds indoors under fluorescent lights to get a jump on the season. Remember not to start them too early. Find out the average last day of frost in your area and figure backward as to when you should start the seeds. The seed packet will tell you if you need 6, 8 or 10 weeks lead time. Follow that date since, if you start the seeds when you get them in mail in January, you will run out of room under your lights long before you can plant them outside.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

 

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