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Do Petunias Spread? (Plus 5 Reasons Yours Aren’t)

Do Petunias Spread? (Plus 5 Reasons Yours Aren’t)

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Petunias can turn your garden into a magical place with their vibrant colors and heavenly fragrances. You can never get enough of these magnificent flowers.

What can make your garden even more merry is a ground cover of eye-catching petunias.

So, you’re probably wondering: Do petunias spread?

The answer is yes! Some petunia species can spread quickly, covering the surrounding area with abundant blooms in a single growing season.

Do you want to find out more?

In this article, I’ll tell you everything you need to know about petunia self-spreading.

Let’s jump into the details right away.

Do Petunias Self-Seed?

Yes! These popular flowering plants can reseed themselves and come back the next year if the conditions are suitable.

After the flowers fade, seed cases appear, containing tens of tiny, blackish seeds.

Some of these seeds can fall from the plant and take root in the soil. With some warmth, moisture, and sunlight, a petunia seedling will emerge.

You can either leave the baby plant where it is or transplant it to a more suitable place.

Keep in mind that the new flowers won’t be identical to their parents. The new plants will probably be smaller with white, pink, or lavender flowers.

Do Petunias Spread in Pots?

Some types of petunia require a large space to grow and spread, while others can do fine in a pot or a hanging basket.

For example, multiflora petunias are small and dense, so they can spread in pots. On the other hand, wave petunias thrive in gardens and large areas.

When it comes to milliflora petunias, they grow best in pots and don’t spread as much as other types.

Do Trailing Petunias Spread?

If you grow trailing petunias in a large, open area, like an outdoor floor bed, they’ll spread several feet in a short period.

Trailing petunias can spread to around three or four feet, depending on the growing conditions.

These low-growing flowers can live happily in window boxes and hanging baskets. Yet, they won’t spread as much.

Do Wave Petunias Spread?

Wave petunias are perfect for ground cover. These flowers can spread rapidly, covering the surrounding area with astounding blooms.

Typically, wave petunias can spread over a width of three to four feet in a garden. In optimum conditions, they can spread even further.

So, some gardeners recommend cutting back the spread to avoid having straggly petunias.

How Do Mexican Petunias Spread?

Mexican petunias, also known as Ruellia simplex, spread through seeds and rhizomes. As a matter of fact, the spread of Mexican petunias can get out of hand sometimes.

This petunia variation has a rapid growth rate, which can lead to large clumps that are difficult to remove.

Not only that, but the roots of these petunias are large. Although they often peek aboveground, they aren’t easy to get rid of.

In addition, the seed capsules of these plants can scatter seedlings far and wide, making the spreading process even quicker.

Unfortunately, if you leave Mexican petunias unmanaged, they can get invasive.

The problem is that even if you manage your plant, it can spread out of your garden and into natural areas. Taking over a natural area won’t be a tough job for these highly spreading plants.

That’s why the University of Florida advises against planting it in home gardens. However, not all cultivars are this bad!

Purple showers, for example, is a cultivar that has been tested and proven not to be invasive.

How Far Do Petunias Spread?

Petunias can spread in your garden anywhere from 18 inches to 4 feet, depending on plant type and growing conditions.

The better the conditions, the further your plants will spread, creating a carpet of vibrant colors and amazing fragrances.

How Fast Do Petunias Spread?

It all depends on many factors, including soil conditions, weather, sunlight, and watering frequency.

Generally, petunia seeds take around 7 to 10 days to germinate and sprout. After that, it can take anywhere between 10 and 12 weeks for the flowers to start growing.

Why Are My Petunias Not Spreading?

Unless you’re growing petunias that don’t naturally spread, your plants might be facing a problem.

Many factors may limit the spread of your petunias. For starters, it might be due to underwatering or not receiving enough light.

Additionally, some pests feed on your lovely plants, causing them to be weak.

That being said, let’s check out how to provide your petunias with the best conditions that’ll help them spread.

1 – Site

Ideally, you should grow your petunias in an area where they receive at least five to six hours of sunlight each day.

If you want these plants to bloom, don’t shade them. Although petunias can tolerate shade, they thrive in full sunlight.

2 – Soil

Petunias love well-draining soil that’s rich in nutrients. So, before planting your petunias, add some organic matter or a suitable fertilizer to the soil.

Peat moss, manure, or compost can all make the soil a better place for your plants to grow.

To get the best results, spread the organic matter into a 2-inch layer.

Then, incorporate it into the soil to around 8 to 10 inches deep with a garden fork.

That won’t only make the soil richer, but it can also improve drainage and increase nutrient retention.

3 – Spacing

You can’t expect your petunias to spread and self-seed in a crowded area. The seeds that fall from the plant won’t receive enough water and sunlight, not to mention the high competition for nutrients.

Generally, spacing can differ from one petunia type to another.

For grandifloras and multiflorus, it’s best to space the plants around 12 inches apart. If you’re planting them in a shady area, you can space them several inches closer, as they won’t spread a lot.

On the other hand, milleflores do best four to six inches apart. In the case of ground-covering types, the petunias should be at least 1.5 feet apart.

4 – Watering

To help your petunias spread, you need to keep the soil moist but not soggy.

Petunias don’t typically require frequent watering. Nevertheless, spreading variations require more frequent watering.

If the soil is struggling to retain moisture, you can add mulch and rocks to the gardens. These materials can help seal in moisture for longer periods.

5 – Pests and Diseases

Many pests and diseases can lead to stunted growth and stop the spread of your petunias. Here are some of them:


Aphids are tiny, pear-shaped insects that are hard to see with the naked eye. However, they leave behind white flakes on petunias that are easily recognizable.

Luckily, you can get rid of these annoying insects using a strong stream of water from your garden hose. If the issue persists, you may use a suitable insecticidal soap spray.

Tobacco Budworms

Tobacco budworms are caterpillars that love to dine on your precious petunias. They’re usually brown or green with white stripes that run along their abdomen.

You can tell these caterpillars are the cause of the issue when you spot irregular-shaped holes all over your plants.

The best way to get rid of tobacco budworms is to remove them by hand. It’s also best to remove damaged parts of your petunias to encourage regrowth and spreading.

Powdery Mildew

Does your plant look like it has been dusted with flour? Well, that’s a fungal disease called powdery mildew.

This disease spreads quickly between plants, so you need to act fast.

It’s essential to remove and dispose of any affected parts of your petunias. Then, use a suitable fungicide to eliminate powdery mildew.

Final Thoughts

So, do petunias spread?

Some types of petunias can spread, covering your garden with gorgeous flowers of different colors.

Wave petunias, for example, spread rapidly and require a large area to grow. On the other hand, multiflora petunias can grow well in hanging baskets, but they don’t spread as much as wave plants.

Remember to provide your petunias with the optimum conditions they require to help them spread. Happy gardening!

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