Tall Annuals: Screening & Filling Gaps In Your Garden

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This post contains affiliate links.

Every gardener knows the patience required when planting a new perennial bed or hedge. While we wait for those young shrubs and perennials to mature and fill in the space, the garden can sometimes feel a bit sparse. But don’t despair—tall annuals are the perfect solution to fill in those gaps, adding not just structure but also vibrant color and texture, creating an immediate, dynamic garden.

Annuals, with their rapid growth and bold personalities, can stand tall alongside your slower-growing perennials. Whether you’re looking to add privacy, cover unsightly views, or create layers of interest in your garden beds, these tall performers bring both practicality and beauty to the table. Here’s a look at some of the best annuals that can help bridge the gap while your perennials catch up.

Cleome (Cleome hassleriana)

Often referred to as the “Spider Flower,” cleome adds both height and whimsy to garden beds. These annuals grow quickly, shooting up to 4-6 feet in a single season. But it’s not just their height that makes them stand out—it’s their eccentric, spindly blooms in shades of pink, purple, and white that look as if they’ve been plucked from a fairytale. Cleome is one of those plants that surprises you with its mix of delicacy and resilience. Heat and drought-tolerant, cleome thrives in full sun, making it an excellent filler for those wide-open spaces where more delicate plants might falter.

Amaranth (Amaranthus caudatus)

If you’re craving something a bit more dramatic, look no further than Love Lies Bleeding. This striking annual reaches anywhere from 3 to 8 feet tall, with its tassel-like flowers cascading in deep reds or pinks. It has an almost theatrical quality to it—draping over fences or trailing from containers with a bold, unapologetic elegance. Despite its dramatic appearance, amaranth is surprisingly easy to grow. It loves full sun and can handle some shade, making it adaptable for various spots in your garden. Plus, it’s drought-tolerant, which means you can enjoy its extravagant blooms without the constant need for watering.

Mexican Sunflower (Tithonia rotundifolia)

For those wanting a bit more of a tropical flair, the Mexican sunflower is an eye-catching option. Growing to heights of 4 to 6 feet, this vibrant annual brings bright orange, daisy-like flowers that provide a bold contrast to cooler-colored perennials. Tithonia’s broad, velvety leaves add fullness to garden beds, while its ability to tolerate dry, poor soil makes it a resilient addition to the landscape. As if that wasn’t enough, this sun-loving plant also attracts pollinators like butterflies and hummingbirds, keeping your garden buzzing with activity from midsummer through the first frost.

Zinnia (Zinnia elegans)

Zinnias are the ultimate multitaskers of the garden. These cheery plants not only grow up to 4 feet tall, but they also bloom in a kaleidoscope of colors. With varieties like ‘State Fair’ and ‘Benary’s Giant,’ you can easily fill in garden gaps with bright, daisy-like flowers that bloom all summer long. Zinnias are a bee and butterfly magnet, so if you’re looking to add some life and motion to your garden, these are the plants for you. They also hold their own against the heat and are surprisingly drought-tolerant, making them an easy-care option for gardeners looking to brighten up a space without too much fuss.

Verbena (Verbena bonariensis)

Verbena may be a perennial in some climates, but it’s often grown as an annual in colder regions due to its rapid growth and long-lasting blooms. This tall, airy plant grows up to 4-6 feet and has clusters of small, lavender-purple flowers that seem to float on slender stems. It’s a fantastic filler for those hard-to-reach spots between larger shrubs or perennials, adding an ethereal quality without overwhelming the space. Verbena is also a pollinator favorite, attracting bees and butterflies while resisting drought once established. Plant it in full sun for the best results, and enjoy its delicate blooms from summer through fall.

Canna (Canna indica)

Cannas are the showstoppers of any garden, with their large, tropical leaves and bright, bold blooms in shades of red, orange, yellow, or pink. These impressive plants can reach heights of 6 to 8 feet, making them ideal for creating temporary privacy screens or filling large gaps in garden beds. Cannas thrive in full sun and moist, well-drained soil, and while they’re perennials in warmer climates, they’re often treated as annuals in cooler regions. If you’re looking for a plant that brings drama and a touch of the tropics to your garden, cannas are an excellent choice.

Sunflowers (Helianthus)

…and of course, sunflowers. There’s something undeniably nostalgic about sunflowers. They’re the giants of the annual world, with varieties ranging from modest 3-footers to towering 15-foot plants that seem to scrape the sky. Sunflowers not only offer height but also a rich splash of color with their iconic yellow blooms. Varieties like ‘American Giant’ or ‘Mammoth’ are perfect for screening and can create a striking backdrop to shorter plants or line a fence for added privacy. In addition to their good looks, sunflowers are tough—they thrive in full sun, withstand heat, and can handle less-than-perfect soil, making them a workhorse in the garden. Plus, their seeds can be harvested for snacks, or left for birds to enjoy through the colder months.

Bottomline…

While your hedges and perennials take their time growing into mature beauties, tall annuals offer a dynamic, fast-growing solution for filling in garden gaps and adding much-needed structure. From the towering sunflower to the whimsical cleome, these plants not only provide coverage but also bring their own unique charm to the landscape. And the best part? Many of them are self-sufficient, drought-tolerant, and will reseed themselves, giving you a head start for next year. So, embrace the temporary beauty of tall annuals while your garden’s permanent residents take root—they might just steal the show in the meantime.

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BesideTheFrontDoor - Smallgrove is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. We also participate in other affiliate programs which compensate us for referring traffic.