The stunning color of petunias can be the crowning glory of your flower garden. It’s a shame they can’t be permanent. How long can you expect to enjoy these classic summer plants?
When you’re wondering how long do petunias last, you might be considering two different things. How long do the plants themselves actually live for, or perhaps you want to know how long the flowers last once your petunias bloom?
To tackle the first part of the question, petunias can live for 2 or 3 years but generally behave as annuals because they can’t survive the freezing temperatures of the winter. More on that below. For the second part, it’s difficult to really put a timeline on each individual blossom. They’re not particularly long-lived, but the plant puts out so many of them that you may not really notice.
How to Make Petunias Last Longer
When you want your outside petunias to live longer than a single season, you have to protect them from the cold. The most effective way to do this is to bring them indoors. Now, if you plan ahead, you can make this a lot simpler by planting them in portable containers to begin with. If they are already growing in the ground, you may have to carefully dig them up and repot them in the fall before the chilly weather triggers them to die back.
Either way, you can treat them like houseplants until spring, extending the life of your petunias for an extra year or two. But as I mentioned, they do have a natural limit to their lives and will eventually die back for good after perhaps 3 years.
Now if you aren’t looking for overall plant lifespan, you can have your petunias bloom longer with a few simple tricks. The obvious one is to give your plants lots of proper care (more on that below). You can also be quick to pluck off dead or dying flowers to spur the plant to put out more buds. This is called “deadheading” and is a pretty common task to get a flowering plant to do more blooming.
Save the Seeds
Saving the seed from your petunias isn’t quite the same as getting them to live longer, but it will mean that you can continue to plant new petunias each spring without having to completely start from scratch with purchased seed.
Not only do you save a little money by not buying new seeds, you can develop your own personal strain of petunias when you choose only the plants that thrive best in your garden.
Choose a plant that is doing very well, with flowers in your favorite color. Don’t do any deadheading to it, and let the dying flowers set their seed pods. Once the blooms drop off, you’ll see a little bulb develop in their place. At this point, watch your petunia regularly or you might lose your seeds.
Eventually, that little green bulb will turn brown and start to crack open. As soon as you see it split, it’s time to harvest your petunia seeds. Carefully snip off the pods and get ready to dry them.
Lay the pods out on a piece of paper towel, and leave them to finish drying in a cool, dry spot that is also out of the sun. Air drying is what you are after, not baking in heat. Give them a week, and when you can hear the seeds rattling around inside, they are ready to break open.
Gently crush the pods, and pick the seeds out of the debris. Store in a paper envelope where they will stay dry. Next year, you can plant them and keep your petunias going.
Be aware though that many of today’s petunias are hybrids, and may not “breed true.” That just means that your next generation of flowers may not look exactly like the originals. But that would be the case with any plants as these are seeds rather than clones or cuttings. Expect some natural variation.
General Petunia Care
Overall, the best way to have your petunias last as long as possible is to give the best care you can. The most important thing you can do for petunias is give them plenty of sun, without really letting them get too hot. They’re not cacti after all.
They should be watered whenever the soil starts to feel dry to the touch. Unless you live in a particularly dry climate, or are just having a bit of a drought, you probably won’t have to do many watering chores as the regular rainfall should be enough for petunias.
All of those luscious flowers can come at a price. Petunias are very “heavy feeders,” requiring plenty of nutrients in the soil to keep them healthy. While they are outside, plan to give them a dose of compost or aged manure once a month over the summer season.
For petunias that you have moved indoors, the same thing applies. Use a standard houseplant fertilizer that is geared towards flowering plants, and feed your petunias weekly.
Types of Petunias
Though they can be similar, there are several different varieties of petunias on the market you can choose from.
- Grandiflora petunias
- Multiflora petunias
- Spreading (Wave) petunias
Longevity-wise, it won’t matter which one you grow. They all have the same life span. The differences are about flower size and plant behavior.
Grandifloras are the most common, with their usual big flowers and plants that grow upright from 8 to 12 inches high. The multiflora petunias are more compact in shape, and the flowers are smaller.
You can also get spreading petunias for those spots where you want to really cover your space with color. Only 6 inches high, these ones can spread out several feet, still putting out flowers all the way.
No matter which variety appeals to you, there will be a whole rainbow of colors you can work with, in either solid hues or bi-color.
Unlike some plants that can easily outlive a person, petunias are simply not going to last forever. A little extra work and attention can make them last longer, and add a few more colorful years to your garden space.