A Guide to Annual Plants (Flowers)

Annual plants that bloom all summer

Annuals are the names given to flowers that complete their life cycle in one season. The annual flowers in the garden will grow to maturity, set their seeds, and then die when the weather gets cold. Most annual plants will provide flowers abundantly during the entire growing season.

There are plenty of plants that are only annuals in the colder regions of the north United States. These same plants are used as perennials in the extreme southern areas where it doesn’t frost. This is the reason some of these popular flowers will be listed as tender perennials in gardening books. They are sold and used as annuals elsewhere in the country.

Soil Warmth and Preparation

It is best to not plant annuals too early in spring. Most will need the soil to have warmed sufficiently and for the temperatures to also be stable. Don’t plant annuals until all danger of frost has passed for your region. The exception to this is the few cool-weather annuals that can survive frost, such as pansies.

It is always a good idea to prepare the soil before doing any planting and annuals are no exception. Plants grown in the garden are only going to be as good as the soil. The soil is the foundation of a healthy plant. Work organic materials into the soil to improve the nutrients and drainage. This can include peat moss, grass clippings, leaves or compost. There are also several good choices available to purchase in bags for convenience. Some of these bags have a combination of organic ingredients to enrich the soil as well as to improve drainage in clay soils.

Ways to Purchase Annual Flowers

There are several ways to purchase annual flowers to add to the garden. The least expensive way to buy annuals are seed packets, but they will require more patience. Seed packets are so inexpensive that they allow for experimentation without breaking the budget. Annual plants are also readily available at garden centers in what is known as cell packs. These consist of small seedlings planted typically in groups of four, six or eight. Each seedling will be separate and easy to plant.

Several of these small cell packs fit into what is called a flat. Many retailers will allow the individual cell packs to be purchased for about $3.00 or purchase the entire flat. The flats can usually be mixed with any combination of annual plants. The number of cell packs per flat varies.

Annual flowers are also sold in larger individual pots throughout the growing season. The larger the pots the more expensive the annuals will be. The pot size can vary from small 4 inch starter pots to larger patio pots. Many varieties of annual flowers are also available to purchase in hanging baskets.


Keep the newly planted annuals well watered unless there is a sufficient amount of rainfall. It’s always better to water deeply and sufficiently and not water as often. A frequent watering that only wets the top of the soil doesn’t promote deep root development. This is true for all types of garden plants. Unless the water goes deep into the soil, the roots will not either. When only the soil surface is lightly watered, plant roots will turn and grow upward searching for water during droughts.

It’s best to water early in the morning. There is less evaporation than during the heat of the day. Most garden experts do not recommend watering at night because it can promote fungal growth. My experiences have been fine with night watering, but it will vary by regions and temperatures.

It helps to add two or three inches of mulch to help the soil retain moisture and to help eliminate weed growth. Mulches also help to keep the soil temperature cool during the summer. Be sure to keep weeds pulled out of the flower garden as soon as they appear.


Some annual flowers do not require deadheading. Deadheading is simply keeping the flowers picked off as they fade to keep them from setting seed. Flowers such as the popular shade-loving Impatiens keep themselves neat and tidy because the faded blooms drop from the plant. The annual wax begonia and vinca also doesn’t require deadheading.

Unfortunately, most flowers don’t keep themselves so fresh looking. Petunias are notorious for needing to be deadheaded on a regular basis. This will not only keep them looking better, but it also will keep them flowering longer. Marigolds and zinnias perform better if deadheaded. Coleus is the popular annual used more for its colorful leaves. When it begins to send small flower spikes from the tips, just keep them pinched off.

Other annual plants will also need to be cut back when initially planted to allow them to branch out and get bushy. There are other flowers that need to be cut back by a few inches in the middle of summer. Some just naturally get “leggy” as the summer progresses. This will allow them a fresh start with new growth and flowers.

Uses of Annual Plants

Annual plants can be grouped together in masses for big color impact or just sporadically placed in the gardens to fill in bare spots. Just remember to read the nursery label for the annuals. Some of the same flower types can vary in height. For example, the annual marigold has a dwarf variety that only reaches about ten inches in height. There is also a marigold that grows two to three feet. There are other annual flowers that vary considerably as well. Snapdragons are another example that has a dwarf and a tall variety.

Annuals can be effective mixed on a large scale with a perennial border. Gardeners often use annuals to fill in spaces while the perennials are still maturing. .There is an annual flower for just about every light and soil condition. Whatever type of perennials planted in the garden, you can be sure there are annual companions. Many annuals also make excellent cut flowers.

There is no reason for a vegetable garden to not have colorful flowers. Some annuals actually are needed companions to vegetables. One such example is marigolds and tomatoes (botanically a fruit). The marigolds repel soil nemotodes that feed on the tomatoes roots.

There are annual varieties suitable for sunny, hot, and dry conditions. Annual plants have several choices for full shade as well and just about everything in between the two extremes. The amount of sun or shade for each annual will depend upon the climate for your region.

Versatile and Colorful

Annual plants will also give the much needed color from flowers before, during and after the perennials stop blooming. Annuals bloom in just about every color imaginable. They are really a lot of fun to experiment with as well. The colors of flowers can also be used to create illusions in the garden. Hot colors such as reds, oranges, yellows and brilliant pinks seem closer in appearance. The cool colors of blues, purples and whites seem farther away which can make areas appear to recede.

Even though annual plants complete their life span in one season, this doesn’t always indicate they are gone forever from the garden. Many varieties of annual flowers will self-sow their seeds in the garden or wherever the seeds might fall. They are little surprises each spring. I leave the seedlings to grow where they sprout if possible. Occasionally they will need to be transplanted to other areas, but I always look forward each year to see what surprise nature will send my way!

These are just a few examples of popular annual flowers for shade to part-shade: begonias, impatiens, coleus, Fuschia, torenia, pansy, lobelia, and sweet alyssum.

Popular annual flowers for sun: salvia, annual vinca, petunia, dusty miller, zinnia, marigold, portulaca and celosia.

Best annual flowers to grow from seeds: Morning Glory, Sweet Pea, Cosmos, Nasturtiums, and the ultimate flowering annual- the Zinnia.

Theresa Lien
Theresa Lien
A professional writer who has specialized in houseplants and indoor gardening. She's had experience with outdoor landscaping too, having written about plants that grow well on balconies and patios as one of her previous articles for Wohomen.


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