Annual vs. Perennial: An Expert Explains How to Plan Your Garden

Every garden needs a curated mix of spring flowers, ornamental grasses, flowering shrubs, and trees—or not so curated, if you're into chaos gardening or rewilding. Trees are easy to classify as deciduous or evergreen (some lose their leaves and some don't) based on their looks alone, but flowers aren't so simple. You might wonder why some of your favorite flowers come back each year and others don't. The key is knowing whether the plant is an annual vs. perennial. For example, daylilies are perennials, but petunias are annuals.

While it's a personal preference whether you grow one or the other in your garden, landscape designer Kat Aul Cervoni of Staghorn NYC recommends a bit of both. “For a dynamic mix of flower types and season-long color, planting a mix with different blooming windows is ideal.” Plus, understanding the difference between the two types of plants can help you plan and maintain your outdoor space.

Annuals and perennials are also great for different purposes and different garden types. Aul Cervoni is helping us break down the difference between annual vs. perennial plants, in addition to their pros and cons. And if you're reading this at the end of the growing season, you can read on to learn what to do for each type of flower when winter rolls around.

According to Aul Cervoni, the most basic way to explain the difference between an annual vs. perennial is that perennials survive the winter. “Annuals are one and done, which makes for a great test run,” Aul Cervoni explains. “Perennials will continue to recur each year for up to a decade, these are plants you want to commit to.” A perennial plant has a growing season and a dormant season, and it can survive through the frost to grow again the next year. Annuals, however, survive for one growing season only. Once they die in the winter, they're gone for good.

Many of the most popular garden flowers are perennials (think peonies, irises, and hydrangeas), meaning that they continue to bloom around the same time each year, often for as many as 10 years given the proper pruning and offseason care. Perennials have a continuous growing cycle for as long as they're alive, which is typically three years or more. Annual plants complete their growing cycle in a year and die in the winter.

As the name suggests, an annual is a plant that completes its entire life cycle within a calendar year. Because of this, Aul Cervoni notes that annuals bloom for much longer than perennials, sometimes even all season long. They're ideal plants for containers or temporary gardens. Annual plants can also bring instant, seasonal color to borders and beds in your garden since you typically buy them as mature plants rather than seeds. Many vegetables and crops are technically annuals, along with flowers like zinnias, begonias, and sunflowers.

It's important to know that most annuals are tropical or warm-weather plants that can't withstand cold weather or even cold spells in Northeastern springs. “They may need a bit more fertilizer and water to get going because they're growing and blooming all in one go,” Aul Cervoni says. “Their roots aren't as deep, but we love annuals for their full-season color.” Once the growing season is done, annual plants must be cut back and removed since the original seed will not bloom again.

Longer Blooming Time

Most annuals bloom for months, lasting through the entire spring and summer. This is why they're so popular, says Aul Cervoni. Gardeners know that they're getting full color for a lot longer.

Best for Small Spaces

Because you can toss them out at the end of the season, annuals are much friendlier to small-space living. They don't require any maintenance during the offseason and have no bulbs to store inside.

Low Commitment

As Aul Cervoni mentioned above, once you're done with annuals, you're done. The first frost of the season will cause them to shrivel up and dry out. She recommends composting the remnants as fertilizer for next year's batch.

One Season Only

The primary con to growing annuals is that they only last one season. While this is great for plants you're unsure of or want to test out, it can be annoying to pull them out year after year. Aul Cervoni recommends growing annuals in containers or temporary planters for easy transfer.

Smaller in Size

Because annuals only have one season to get acclimated and grow in your garden, their roots often don't reach as deep or as securely as perennials. Using extra fertilizer or compost can help promote their growth at the beginning of the season.

Harder to Grow from Seed

Because of the short time frame, annuals are rarely grown from seed in a garden bed unless started early enough. Aul Cervoni recommends planting them in mid-March when you know the worst of the winter is behind you. Alternatively, you can save yourself that extra work (and anticipation!) by buying mature annuals at your local garden center that you can plant directly into a bed or planter.

Blooming and sprouting year after year, perennials are known for their longevity, spanning multiple years and growing cycles. (Think dahlias, hostas, and ornamental grasses.) Like any plant, perennials have a peak season and an offseason, meaning they'll bloom around the same time each year as the cycles restart. “A perennial's peak season can range anywhere from three weeks, like peonies, to a couple of months, like grasses,” explains Aul Cervoni. Because of their short growing cycles, Aul Cervoni recommends looking into succession planting, in which you choose plants with different peak times to ensure a colorful garden all season long.

Because they continually go dormant and come back, perennials require some maintenance to ensure beautiful growth year after year. Pruning them each winter, after the first frost, allows the plant to reset before beginning to grow again. Perennials also need extra care during the growing season as they're more prone to wilting during heat waves—you may need to add water or fertilizer periodically. Perennials can last anywhere from three to 15 years, so choose flowers and plants you can see yourself loving for many seasons to come. Of course, you can always rip them out if you're looking for a change—but that would defeat the purpose of choosing a perennial!

Longer Overall Life Cycle

Perennials are known to last for years—sometimes up to a decade. This is great for gardeners looking to commit to a plant and leave it be for many years to come.

More Readily Available

The most popular garden plants are perennials, so you're more likely to find these as bulbs or seeds at your local garden center, especially earlier in the season.

Less End-of-Season Maintenance

Rather than having to tear up the entire root system, like you do with annuals, perennials just need to be trimmed back for overwintering. “I recommend leaving an inch or two to allow winter critters and insects to still feed on the seed head,” Aul Cervoni says.

Shorter Bloom Times

Some perennials, like peonies, have notoriously short blooming windows. We're talking just a few weeks. This can be annoying for gardeners who want more season-long coverage from their bloom.

Less Resilient to Hot Weather

Perennials are more suited to milder and cooler climates than their tropical counterparts (the annuals). You may find more water or shade is needed to help keep your perennials perky through summer heat waves.

Winter Pruning

To maintain a healthy perennial that successfully comes back each year, you must prune the dead seed heads each winter or spring. This extra effort can help your garden aesthetically while also taking some weight off the roots that are trying to recover.

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Expert consulted:Katherine Aul Cervoni

Katherine "Kat" Aul Cervoni is the founder and principal of Staghorn as well as the blog, The Cultivation.