Petunias have long captured gardeners’ hearts with their stunning colors and bold blooms. Get the most out of these beloved annuals by learning how to deadhead petunias to promote new growth and continuous flowering. Deadheading is a simple pruning method used to remove flowers after they die back, which encourages plants to produce more blooms by preventing seed formation. Taking the time to deadhead petunias will keep your plants blooming all summer long.

When To Deadhead Petunias

There are no hard and fast rules for when to deadhead petunias, as timing is based on the plant’s individual bloom cycles. Watch your petunias and deadhead plants as soon as the blooms start to fade. Spent blooms are easy to identify, they shrivel up, go limp, and begin to turn brown. Removing spent blooms will prevent plants from shifting their energy into seed production.

Although plants will eventually drop spent flowers on their own, the ovary does not fall off. Remember, plants produce flowers as a means of reproduction. When spent blooms are allowed to remain on the plant, petunias focus their energy on maturing seeds inside the ovary instead of producing new flowers. When we remove flowers and developing seeds through deadheading, the plant essentially tries again by producing more flowers. In a way, deadheading is used to trick plants into blooming again and again. 

Some petunia varieties, such as Wave petunias and Supertunias, are self-cleaning and do not require deadheading to keep plants blooming. However, these plants may benefit from occasional pruning back to promote bushier growth and many gardeners like to remove spent blooms to keep plants looking tidy. Some self-cleaning varieties may also put on a larger flush of flowers with deadheading. 

Methods For Deadheading Petunias

When deadheading petunias, it is important to pinch off not only the flower, but the flower stem as well. This will ensure that you remove the developing seed. To accomplish this, pinch, don’t pull. Use your thumb and forefinger to cut the stalk of individual flowers back to the main stem. If you simply pull the flowers off, you are likely to leave the ovary behind intact.  

Petunias tend to be sticky. You may wish to wear gloves when deadheading or use pruning tools rather than your fingernails to cut flower stalks. Mini flower snips work well for this type of pruning. Some gardeners like to use a thumb knife and protective finger sleeve for deadheading. Thumb
knives are silicone sleeves that slip over your thumb and hold a small blade where your thumbnail is located, giving you more cutting power per pinch. 

There are times when you may wish to cut back the entire stem rather than remove individual flowers. This type of pruning is helpful when plants have grown leggy or when numerous spent flowers cover stem tips. You can remove one-third to one-half the length of each stem when cutting back to encourage branching and new growth. Cut each stem back to a side branch or bud. This will produce a denser plant and promote blooming.  

Depending on how much material is cut off, plants may take a week to two to put on new blooms. You can achieve the benefits of pruning while maintaining some flowers by cutting back a few stems at a time over the course of a few weeks. If you live in a location with a long growing season, you may wish to cut plants back two to three times over the course of the summer. 

Frequency Of Deadheading

Deadhead petunias on a regular basis throughout the growing season to prevent seed formation and keep plants blooming. Many gardeners like to check plants daily, pinching off spent blooms as soon as they notice them to keep plants looking their best. This results in less work each time you visit plants but is not practical for everyone. For busy gardeners, deadheading plants at least once per week is enough to encourage continuous flowering. A good schedule for most gardeners is deadheading two to three times per week. 

Taking the time to deadhead petunias will keep your containers, window boxes, and hanging baskets looking their best all season long.