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How To Keep Petunias Flowering – 3 Secrets To More Blooms!

Want to keep your petunias flowering bigger, better and longer than ever this year?

Petunias are one of the classic flowering annuals of summer. With varieties available in nearly every color of the rainbow, they are not only eye-catching, but add a classic elegance to wherever they grow. Especially when they are loaded with blooms.

Petunias grow beautifully and easily in containers, hanging baskets, window boxes, flowerbeds, and directly in the ground. You can find varieties that trail and others that produce wave after wave of tiny blooms. So much so that it’s almost mind-boggling just how many choices there are!

Bright pink petunias in transplant containers - how to keep petunias flowering
Petunias are one annual flower that start off strong but seem to always fade by mid-summer. But with just a few simple tricks, you can keep this gorgeous annual flowering all the way to fall!

But if there is one thing gardeners struggle with when it comes to petunias, it’s that by the middle of the summer season many seem to lose their luster. Not only do they often begin to produce fewer and fewer blooms, but the plant’s foliage often becomes wispy and faded.

But with just a few tricks and tips, it doesn’t have to be that way. In fact, by making sure to take of 3 basic and very simple needs for your petunias, you can have them growing healthy, strong, and continuing to flower not just past mid summer, but deep into late fall as well!

The 3 Simple Secrets To Keep Petunias Flowering

#1 Fertilizing Slow & Steady

Petunias produce a steady stream of blooms, and because of that, they require a large amount of nutrients. But the key to blooming success is to provide those vital nutrients at a nice low but consistent pace through the season.

Petunias typically grow in containers and hanging baskets – where they have limited soil to find nutrients. As the plants grow, they quickly deplete those resources to power growth and blooms. And without replacing those nutrients, they can quickly begin to struggle and fail.

But is in replacing those nutrients where many gardeners often make a critical mistake – giving their plants too much energy all at once. By providing petunia plants with a large dose of fertilizer, chances are the plants will end up producing a lot of growth and perhaps even a large number of blooms in a short period of time. 

That sounds like a good thing right? Unfortunately, it’s not. Because all of that fast growth creates and oversized plant with oversized roots – and one that can’t sustain it’s growth all season. Quite often, over-fertilizing also can also cause plants to focus solely on creating foliage instead of blooms.

A watering can dispersing compost tea onto the base of petunia plants.
Using worm castings tea is a great way to provide low and steady nutrients to flowering petunias and other annual flowers.
How To Fertilize Petunias Correctly

The answer to this issues is to give your petunias smaller doses of energy, but at a consistent pace. A low and slow pace truly is the first key to keeping your plants healthy and flowering at steady pace. This approach to fertilizing is actually great for all annual flowers – and vegetable plants too.

If you are using a commercial liquid fertilizer, aim for a mixture that is around one-half to one-quarter of the recommended dosage. Apply the reduced mixture every 10 to 14 days to keep a steady stream of nutrients to your plants. Affiliate Product Link: Espoma Bloom Booster

As a great, all-natural option, consider using compost tea or worm casting tea instead of commercial fertilizers. Using the teas weekly will give the plants a balanced dose of nutrients without the risk of overpowering plants. There is no need to dilute either of these two options.

A bonus to using compost tea or worm casting tea is that they can be absorbed by the root of the plants. In addition, you can also apply them directly on the foliage as well without the risk of burning delicate tissues. 

Finally, one last great way to add even more low and slow power is with worm castings. In addition to fertilizing, add one cup of worm castings to the soil around your plants every month. Every time you water your petunias, you will be giving the plants a light boost of nutrients as the water soaks through the castings. (See: “How To Use Worm Castings To Power Plants”)

#2 Watering For Success

The second key to keeping petunias flowering is proper watering. Not only does the amount of water you use matter – but when and how you water them is equally important too. 

red petunia flowers dying because of a lack of watering.
Without proper watering, petunia plants can fade long before summer is over. Inconsistent moisture causes roots to shrivel and or swell – both of which keeps them from absorbing nutrients.

Potted or container plants tend to rely more on frequent watering than their in-ground counterparts. However, you also don’t want the plants to be sitting in constantly wet soil either. If you water your petunia plants too frequently, their roots can begin to rot, weakening the plants. 

Yellowing foliage will often be your first sign of over-watering, while drying and shriveling foliage can indicate a lack of water. Both of these cause the roots to stop taking in nutrients as they either shrivel from drying out, or swell from being water logged.

How To Water Petunias Properly

As with all plants, checking your petunia plant’s soil prior to watering is the key to avoiding over-watering and underwatering. 

Place your pointer finger down into the soil. If the soil is still moist (sticks to your finger) at around the one-inch mark, hold off on watering. But if the soil is dry, you’re plants need moisture. You can also use an inexpensive moisture meter to quickly tell you the soil’s moisture level. Affiliate Link: Moisture Meter

Try to only water your petunia plants early in the morning. This will hydrate them early, allowing them to dry out slightly throughout the day. Also, avoid getting water in the trumpet-shaped blooms. This will cause the blooms to fade more quickly. Instead, water plants at the base underneath the blooms if possible. 

Finally, water container plants deeply until you start to see water seeping out of the drainage holes. This promotes plants to grow deep roots, creating sturdier and stronger plants. 

3. Deadheading 

Last but not least, the final secret to keeping your petunias flowering strong from summer through fall is deadheading spent blooms. And yes, it really does make a BIG difference!

A hand pinching off a spend petunia bloom and seed head.
When deadheading, don’t just pull the spent bloom off of the plant. Instead, pinch the bloom off just underneath the green seed head.

As old blooms start to die off, they will shrivel up and their color starts to fade. These spent blooms don’t look the best on plants, but there is more to it than just appearances. Dying blooms are still using up nutrients and resources from the plant’s soil.

Unfortunately, the plants will continue to send resources to the blooms instead of focusing on creating new blooms as long as they remain. And that is exactly why removing them can help your plant conserve that energy to use instead for new blooms!

How To Deadhead Petunias

Thankfully, deadheading (removing spent flowers) is not only easy, but quite a quick chore to perform as well. There are a few pointers though when deadheading that can help your plants bloom out more quickly.

While it might seem like you can just pull the petals off of the plant because they dislodge so easily when they are fading, that can leave behind the seed head. You actually need to pinch off right below the seed head, taking it and the petals off of the plant entirely. 

Using a clean pair of small pruners works well, but you can easily just use your fingernails to snap off the delicate stems if you prefer. Deadheading plants once every couple of days is all you need to allow plants to focus their energy on creating new blooms instead of repairing dying ones. 

Here is to keeping your petunias flowering strong all the way to fall this year!

Simple Garden Life is a website dedicated to keeping gardening fun, simple and enjoyable! We publish two new articles each week along with a new garden podcast episode every two weeks. This article may contain affiliate links.