How To Deadhead Zinnias So They'll Bloom All Summer Long

Zinnias are gorgeous flowering annuals that attract butterflies to the garden and make excellent cut flowers. To keep zinnias blooming all summer long, flowers should be removed as they begin to fade. This is called deadheading, a simple pruning technique that encourages new growth and reblooming. Learn how to deadhead zinnias to keep your plants blooming continuously, summer through fall.

Why Deadhead Zinnias

Zinnias are deadheaded to encourage plants to produce more flowers. Zinnias are annual flowers—their life goal is to reproduce. At the beginning of the season, they focus their energy on growth and blooming to attract pollinators like butterflies and bees. Once their flowers are pollinated, plants stop blooming and shift their energy into producing seed.

When we deadhead zinnias, we cut away those pollinated flowers before they can develop seed. The plant tries again, quickly sending out new flowers to replace the ones you cut. Deadheading, in essence, tricks the plant into reblooming. By repeatedly deadheading zinnias throughout the summer, you can keep plants in the flowering stage, provide long-lasting color.

Deadheading also keeps plants looking their best. Most flowers lose their attraction as they fade, leaving an unsightly brown head behind. For some newer hybrid zinnia varieties, including those in the Profusion Series and Zahara Series, deadheading isn’t entirely necessary. These hybrids continue to bloom without deadheading, however, clipping off spent flowers keeps the plants looking tidy and fresh. 

How Often To Deadhead Zinnias

Zinnias grow and flower very quickly after sowing, which is one reason they are so popular. Begin deadheading as soon as the first blooms begin to fade. The bright colors of spent flowers will dull or turn brown, indicating the bloom is past its prime and ready to remove. If you missed this cue, that’s okay, deadhead declining flowers as soon as you notice them.

Each individual zinnia flower can last for several weeks before it needs to be removed. Once the first flush of blooms starts to fade, you may want to walk through the garden every few days to remove spent flowers. Spending a few minutes every couple of days makes deadheading a much easier task. And it gives you a reason to spend time in the garden, which can be quite relaxing. In fact, many gardeners find deadheading enjoyable and meditative.

As plants respond to deadheading, you are likely to have a lull in deadheading until the next flush of flowers matures. Though deadheading is not something you will constantly need to do, it will be an ongoing task throughout the summer. Toward the end of the season, you can leave spent flowerheads standing to provide seed for birds and for collecting to sow the following season. Zinnia seeds are sensitive to freezing temperatures, so it is best to collect seeds and store them indoors over the winter. In spring you can sow the seeds in the garden after the threat of frost has passed.

How To Deadhead Zinnias

Deadheading zinnias is quite simple—you just need a clean, sharp set of pruners or flower snips. Make each cut just above a set of healthy leaves. This prevents you from leaving unsightly bare stems sticking up from the plants. If you want to keep your zinnias growing tall, cut spent flower stems back to the first set of leaves.

Some gardeners like to cut stems farther back to manage the height of their plants. Zinnias are resilient plants and respond well to cutting back, just remember to make the cut above a set of healthy leaves. Don’t be afraid to give zinnias a good trim when needed, it is hard to kill these hardy plants. 

Zinnias produce a sulfur compound on their leaves that is mildly toxic if eaten. Be sure to wash your hands after handling zinnias or wear gloves when pruning. The toxin is nothing to worry about, just don’t eat your zinnias!

Thanks to their profusion of blooms, zinnias make great plants for beginning gardeners. With occasional deadheading, you will be rewarded with vibrant blooms all summer long.