Annuals vs Perennials: Differences for a New Flower Gardener -

What is the difference between annual and perennial flowers? What do the terms mean, and what kind of flower is best for your unique situation? In this article I’ll present some basic definitions and the practical differences that will help you build the landscape you want.

perennial bright pink peony bloom and purple irises in background — A bright pink perennial peony bloom, with perennial irises in the background. Image © familysoil.com

1. Annuals vs Perennials: Which is which?

An annual is a plant that lives for one growing season and then dies over the winter. Annuals are replanted every year (annually) in the garden. In contrast, perennials go dormant over the winter and return from the same root system the following spring.

The above-ground growth of a perennial flower plant dies at the end of the growing season. However, a perennial’s roots continue to survive underground, as long as they are hardy in your growing zone.

(Hardiness is a measure of the coldest temperature a plant’s roots can withstand. Everyone lives within specific, numbered growing zone that is easy to look up. Some plants that are annual in very cold growing zones will actually grow as a perennial in a warmer zone.)

When it is warm enough the following spring, the dormant roots will send out new leaves and flowers. Perennial roots grow a little more each year until they reach full size, allowing the entire plant to grow and spread with time.

Now let’s talk about the some practical differences between annuals and perennials.

Strawflowers, a fun-to-grow annual that retains its color when dried. Image © familysoil.com

2. Annuals vs Perennials: Length of Bloom Time

Annual flowers will commonly bloom all summer, from the time you plant them in the spring, until the first frost of the fall. The individual flowers will open and fade, but new ones will continually replace them. Many annuals therefore benefit from “deadheading,” or removing the fading blooms, in order to encourage more flowers.

Because of this ability, annual flowers provide a steady source of color throughout the growing season. Their long bloom times are a major reason people choose to grow annuals. It is also why annuals make a great choice for container plantings, and are a mainstay of cut-flower gardens and farms (for bouquets).

In contrast, most perennial varieties will only bloom for a few weeks during the growing season. Perennial foliage (leaves) will still be green and attractive in the garden, but the flowers themselves will only be present in the spring, summer, or fall. For this reason, designed perennial gardens showcase a careful mix of plants that will take turns blooming throughout the season.

There are exceptions to this of course. Some perennials do bloom twice during the season, especially if you cut the plant back after its first bloom period. Others have fairly long bloom times. But in general, if what you want is a simple and bright pop of color in your flowerbed to enjoy all summer, annuals would be the preferred choice.

monarch butterfly on annual polar bear zinnia — A monarch butterfly enjoying a white, annual zinnia among the yellow, perennial coreopsis. Image © familysoil.com

2. Annuals vs Perennials: Price Per Plant

Annuals, often sold in packs of four to six, tend to be quite a bit cheaper to purchase per plant than perennials are. The price difference is because annuals are usually smaller and younger at the time of purchase.

That said, annual flowers typically grow quickly to fill empty spaces between plants. For example, petunias are usually purchased quite small, but grow rapidly through to fill a larger space. So generally, annuals are cheaper per plant, but the plant size and growth is much different than slower-growing first-year perennials.

Perennials tend to cost a bit more, in part because they’re older and larger than annuals at the time of purchase. But perennials are also a longer-term investment. That said, if you have the patience and time, the perennials you purchased in the first year can often be divided into additional, smaller plants two to three years later.

Growing perennials from seeds are also an option to reduce costs, particularly if you wish to have many plants of the same variety. (What I mean by this is you’ll get lots of seeds per packet, rather than having to invest in many different seed variety packets also.) But starting from seed requires some additional basic equipment.

Lastly, if you know a gardener with perennials, it is possible to get new-to-you perennials when they’re dividing their older plants. Many of my first perennial plants were from my mom. She had dug them out because she felt like changing her garden, or her plants just needed to be divided (see below on perennial upkeep).

3. Annuals vs Perennials: Garden Work and Upkeep

Annuals

The main work of growing annuals is planting them in the spring, followed by regular watering throughout the summer. Over the long haul, annuals add up to more planting work compared to perennials.

Annuals require planting every single year in the spring, and often need more individual plants (and therefore more holes dug) to fill a space. Annuals grown directly from seed, like wildflower mixes that are shaken over the soil and raked in for a more rustic look, are an easy annual option to consider though.

Watering requirements for all flowers vary, but in general, annuals require more attentive watering due to their smaller and less developed root systems.

Also, annuals that grow from bulbs or tubers (instead of nursery seedlings or seeds), such as cannas, dahlias, gladiolus, etc., require one additional task every year. These annual root systems need to be dug up at the end of the season and stored for next year. Perennial equivalents of these plants remain in the ground safely over the winter.

Perennials

In its first season, a newly-planted perennial will require a similar level of work to annuals. First-year perennials need consistent watering while establishing their root systems. However, once it is established, particularly in the second year or later, it can typically survive with less upkeep.

Depending on your climate and weather, all flowers will benefit from consistent watering appropriate for the variety. However, due to their strong root systems, the most low-maintenance, drought-tolerant plantings are usually perennials. If you are looking for a hands-off option for your own yard or an offsite location you don’t visit regularly, drought tolerant perennials are an excellent choice. (See a link below in the Section 6. Additional Resources.)

Another consideration about perennial flower workload is that perennials will grow throughout their first year, come back for successive years little larger each time until they reach their maximum size.

Some perennial varieties spread so much they need to be divided into smaller plants. This prevents them from dying out in their centers, flopping over really badly along their margins, and generally prevents overcrowding. A struggle for nutrients between crowded roots will cause the plant to lose health and vigor overall.

Dividing perennials can involve some serious work digging and separating roots with a spade and other tools. So the work you skipped by not having to replant every year with your hand trowel, might come back around in the form of heavier digging with the spade. Folks who have limited mobility or other physical limitations may need help with the business of dividing some perennials.

Morning glories. A classic and easy-to-grow annual that will make you smile every morning before fading in the afternoon. Look for sterile varieties to discourage vines from reseeding themselves and becoming a nuisance.

4. Annuals vs Perennials: Variety in Size, Shape, and Color

Along with trees and shrubs, perennial flowers are often the backbone architecture of formal flower gardens. Perennial varieties provide more options of sizes, shapes and textures than most annuals will alone.

Perennial plants have the energy from their multi-year, well-established roots to put out tall, large, dense foliage and showy blooms. If you travel to a professionally-maintained show garden, there’s a good chance much of what you’ll see are perennial flowers, with additional annuals added for extra color and design flexibility.

There are certainly exceptions, but many of the most commonly available annual plants have similar growth habits. They are often either somewhat low and sprawling or bushy, or taller with longer stems like zinnias, wildflower mixes, and even sunflowers that you might grow from seed.

Foliage (the leaves) on annuals tend to be a little less impressive, because annuals take their energy harvested from the sun and put it into growing seeds for next year’s plants (flowers). Whereas perennials capture energy with their foliage, but use it to store energy for the winter in their roots systems in addition to growing flowers.

5. Summary, Tips, and Suggestions

The points made in this article are meant to draw contrasts between annuals and perennials for the novice. However, many gardeners incorporate the benefits of both freely into the same garden. And there are many non-flowering plants of both types we didn’t even mention that are fantastic to keep in mind also. See the links below for some helpful suggestions on specific plants. Gardening is relaxing. Grab yourself some plants, dive in and have fun!

In summary:

An annual is a plant that lives for one growing season and then dies. Perennials go dormant over the winter, but return the following spring from the same root system.
Annuals bloom for most or all of the growing season, while perennials bloom for shorter, varying amounts of time.
Perennial plants are typically larger and more expensive at the time of purchase. However, over time, perennials are the less expensive option. Particularly if you can obtain plants from a friend with older plants, or wait and divide your own.
Annual plants require more cumulative initial planting work, because they are replaced every year. Perennials only require planting once, but many need to be divided after a few years.
Annuals will require more consistent watering every year, while perennials have a much better chance of surviving on their own once established.
Perennials have more variety of leaves, shape and texture on the whole, and form the backbone, along with trees and shrubs, of many formal gardens.
All flowers will do best planted in conditions appropriate for their variety. So it’s important to plant both annuals and perennial flowers according to their sun and shade requirements, as well as soil and water. See the resources below for tips on annuals and perennials appropriate for sun and shade.