Should I Pinch Back Petunias?

Pinching back petunias leads to fuller growth.

When it comes to growing flowers, each species has its own special requirements and growing techniques that bring out the healthiest plants during the growing season. Petunias require full sunlight, and thanks to their warm-season growth spurts, many growers start them indoors in late winter or early spring and then transplant them outdoors. Pinching back the flowers is one technique that helps promote full and healthy growth.

Early-Season Pinching

You should pinch back the petunia stem when it reaches 6 inches in height. This is especially important if you start your petunias indoors, where they will not receive full sunlight. Low-light growing can cause the stem to stretch out towards the light, resulting in an exceedingly long but thin stem that will not support the weight of the flowers. Simply pinch two fingernails together to cut back the stem to 1 ½ to 2 inches long. If you have trouble actually pinching through the stem, use a pair of clean scissors or shears.

Early-Season Pinching Goals

Pinching back petunias may seem like a counterproductive procedure. Basically, you remove part of the newly growing plant before it even has time to produce flowers. But here's why: pinching off that new, young stem will make room for a stronger stem to grow in its place. Much the way that the skin over a scar is often tougher than the skin that was there before, the plant will growth thicker and stronger stems in place of the area you pinched away. Certain blooms may even sprout two branches where previously only one existed, doubling your chances of seeing flowers.

Late-Season Pinching

Pinching your petunias later in the season involves a completely different method. Also known as "dead heading," pinching at this point involves removing the flowers as soon as they start to fade and wilt. Again, use your fingernails, clean shears or clean scissors to snip back the stem. This time, snip off the head and about 1 to 2 inches of stem below the flower head. Do this as soon as you notice the flowers deteriorating.

Late-Season Pinching Goals

Dead heading increases the chances of the petunia plant actually blooming twice in a single season. Even as the flower begins to die, it will continue to absorb water and nutrients from the soil, using them up and essentially wasting them, since it's dying anyway. When you remove the fading buds, you ensure that the water and nutrients go to healthy, thriving parts of the plant. Just as in early-season pruning, removing part of the stem encourages the healing process, which, when combined with the extra water and nutrients, may result in new flowers in a single season.

References

• National Garden Bureau: 1997: Year of the Petunia
• University of Rhode Island Landscape Horticulture Program: Petunias