The debate over when to use annuals vs perennials goes on among even the most savy gardeners.

The simple reason that everyone has their preferences. There's no right or wrong answer here.
Each choice comes with it's own set of advantages and disadvantages that only you can weight out - and indeed we urge you to do that. Heck, you may want to have both, and there is nothing wrong with that. Nothing at all!
However, if you're a beginning gardener, we have some advice that will surely help you make the decision based on your own planting situation.
Annuals vs Perennials - The Differences
First, it might be helpful to go over the differences are between annuals and perennials. Some of these differences are well known, but some you may not know.
Annuals:
Annuals are a one year plant. They bloom for 1 year and then die. Therefore, they must be entirely removed at the end of the season and re-planted every year.
Perennials:
Perennials come back and bloom each year. Therefore, they are planted once and keep blooming, year after year.
Those are the very, very basic differences that most people know, probably you too.
However, there are some characteristics of each that are not usually considered when deciding which type to plant in your gardens, and that's what we want to talk about next.
Why Annuals
As we mentioned above, annuals bloom for 1 year and 1 year only. However, it's a very good year because annuals will bloom the entire year, continuing to offer up flowers to brighten your gardens.
However, each flower on the annual plant does not bloom the entire year. On most annuals, flowers will come and and go, but there will usually be some in bloom at all times. That means that if they are getting enough sun and water, the color show will continue from the time they are planted until the first frost.
The bottom line, if you want continuous flowers throughout the growing season, with very little maintenance, annuals are what you want. However, you will need to purchase and plant them every year, already in bloom, at your local garden center.
Here in our region there are 2 classes of annuals... summer annuals and fall annuals.
Summer Annuals:
As the name implies, summer annuals are planted at the beginning of the growing season and last all summer long. Plants such as begonias, geraniums, impatiens, petunias and marigolds fall into this class.
Fall Annuals:
These plants usually don't like the summer heat, so they do better in colder weather. The "classic" fall annual here in the mid-Atlantic is the pansy. These cute flowers with faces will not die when cold weather arrives, but will actually survive winter into spring, even with snow on the ground. Here where we live, it's not uncommon to have warmer days in the 40's ad 50's during the winter and when this happens, the pansies will put on a flower show when everything else in the garden is brown and drab. That's why they are so popular.
Other fall annuals include chrysanthamums (mums for short) which only bloom for a few weeks in the fall, purple aster and celosia.
The classic planting schedule that all professional landscapers use here in our region is...
April - May - remove fall annuals (almost all the time pansies) and plant summer annuals.
Sept - Oct - remove summer annuals and plant fall annuals.
Here are some popular annuals that do well with very little care. This is only a small sample:

Begonias
Begonias are a great summer annual because they are a no muss no fuss plant.
They grow in partial shade to full sun and will take some dry weather before they start to wilt.


Impatiens
Impatiens are one of the few annuals that thrive in shade.
For this reason, they are problably THE go-to flowering annuals when your garden is in shade.


Pink Petunias
Ususally trails down so they are commonly used in pots or planters, but can also be used in flower beds where they will spread out.


Marigolds
Usually a bright yellow, marigolds thrive in full sun and give your gardens a burst of color that can't be beat.
All of the previous summer flowering annuals are widely avaiable and would be excellent choices for beginning gardeners.
Search our site for more information on each plant.
Why Perennials
Because perennials come back year after year, they will require a one time investment of time and money, which makes planting them quite appealing.
Generally there are more varieties of perennials offered at garden centers than annuals. In addition to flowering perennials there are a wide assortment of shrub perennials or leafy perennials too. Plus, many perennials will grow in shade, whereas most annuals, with a few exceptions, need sun to grow well.
The disadvantage with perennials is they do not provide contiuous blooms for an entire season and once they finish blooming, their blooms die off and turn brown. Sometimes, as with bleeding hearts, even the foliage dies off. If you don't have time to address these dead flowers and plants often, they will remain unsightly in a garden that would otherwise look beautiful. Beause of this, some people are not fond of a lot of perennials in their gardens.
Some perennials bloom early in the year, some bloom mid-year and some bloom later. The growing zone in which you live determines when they bloom so you'll need to do a little research on your growing zone and plants in your region and then, if you want flowers throughout the year, you'll want to pick plants that bloom at different times of the year.
Here are some popular flowering perennials. This is just the tip of the iceberg:

Coneflowers
The coneflower is a beautiful perennial that grows tall, 4-5 feet at times, and multiplies quickly.
The most common color is pink (pictured) but lately new colors have been coming to market.


Black Eyed Susan
Another gorgeous perennial that grows tall, the black eyed susan is actually the state flower of Maryland, so we are sort of partial to it.
This perennial will put on a show all summer with bright yellow flowers.


Phlox
There are many varieties of phlox, some grow very low and are used as ground cover.
The one pictured grows tall with pink or purple blooms.


Coreopsis
This perennial has yellow flowers like the black eyed susan. However, this plant is more airy and wispy, and the flowers are much smaller.
It can add interest to your perennial gardens with it's different texture.
Here are some leafy perennials:

Hostas
The perfect shade plant... you can't kill hostas.
Pictured are just one of the many varieties on the market. We'd recommend you investigate hostas for the varied interest.


Coral Bells
Great in shade or partial sun, this is another perennial that will thrive without any maintenance.
Coral Bells come in with a variety of leaf colors, from yellow, to burn orange and red to green.


Liriope
This perennial is a grassy looking plant that comes in solid green or vareigated varieties.
It looks great as a border plant or in a grouping with in your beds.
Keep in mind that this page is just meant as an overview. We could not even begin to cover every plant that would fit into the annuals vs perennails topic. There are, literally thousands.
Over time we'll be adding more information on more plants - each one devoted to it's own page, so check back of often and use our search bar to find what you're looking for.
When To Use Annuals Versus Perennials
When to use which depends on what you want to accomplish with your gardens.
Do you want to flowers all season long and are willing to spend the time and money every year purchasing and planting annuals?
Would you prefer to watch the wonder of life - as perennials emerge in the spring and gradually get to full size. Are you willing to spend more money per plant in the begining so that you can save money later by not having to purchase any plants at all?
How about a little of both? Some perennials and some annuals in the same garden?
The only way to know for sure is to research some plants yourself and decide on a plan. You can also visit our "plant guide" routinely to learn more about different plants.
One of the best ways to get ideas is to actually visit your local garden centers where you can see the plants yourself. You'll be able to judge the size, the color and texture of the folliage, the color of the flowers, etc. Our advice would be to visit a garden center with staff that knows a lot about gardening and is helpful and can give you advice.
That being said, here's our advice...
Most professionally desiged gardens use a variety shrubs and/or ornamental trees combined with some leafy perennials such as liriape or hostas, all planted in an overall design that leaves a spot or two for annuals. This is a design we'd recommend you try.
This design is most ideal because much of the garden is filled with shrubs, bushes and trees that will always be there, plus some perennials thrown in that will also always be there. Then, the few spots where you've designated the summer and fall annuals can be planted yearly. This design means that less time and money is spent on new plants each year but you still get the benefit of having flowers in your garden.