3 Reasons to Trim Back Your Annuals

A little pruning now and then keeps it healthy, but you shouldn’t pull it out and chop the roots up.“
– Len Goodman

Some of us feel a little timid when it comes to trimming back our beloved annuals. These bold bloomers captivate our hearts and backyards in their precious, short growing season and we can be nervous to start cutting away their blossoms. It’s time to be brave and grab the trimmers, though, because cutting back your annuals will rejuvenate them for the end of the growing season, boasting bigger, better, and healthier growth into the fall.

Once summer has embraced its best months and we start thinking about the fall and back-to-school season just around the corner, our star annuals that were lush and dense with vibrant color might be looking a little lackluster, despite some of our best efforts. A well-timed pruning can actually give them a second life by trimming the dead weight! Don’t spare the scissors, because they can give your favorite flowers new life to last longer in their prime right into fall:

Pictured below: Petunias

Reason 1: Some of Your Plants Can’t Take the Heat:

When we walk into a garden center to pick out our favorite blooms, we tend to fall in love with the look of our plants first. But a garden center is a bit like the United Nations of plants – something from the depths of the Amazon jungle might be on the shelf beside a desert dweller.

Your petunias are from South America, while Chrysanthemums come from China, and Rosemary originates from Mediterranean countries, like Italy. While they all come from different homelands, we adopt them here in Iowa and group them together in our own container designs. They might survive next to each other in a container, but some plants have some very different needs from each other.

Pictured below: Alyssum

While you’ve probably taken into account the most extreme needs when planting, once the season is in full swing the smaller differences become much more apparent. Annuals from temperate climates will thrive in the cooler nights of spring and fall while folding under the heat of July and August. Classics like Pansies and Violas, Osteospermum, Geraniums, Nemesia, Alyssum, and Snapdragons love cool temperatures and might not be looking their best by this point in the summer.

Once they start to struggle in the heat, they’ll benefit from a generous haircut and some fertilization. Your heat-lovers will be free to put on the best show they can in the rest of the hottest summer days, while the summer pruning will set up your cool-temperature plants to perform again as the days cool into fall. Without this trimming, they’d be too exhausted to even make an attempt at reviving in the fall. By pruning now, you invest in better color, later into the season. Your garden could still bloom with enthusiasm after your heat-lovers finish their season.

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Reason 2: Garden Interventions:

In the gardens of our childhood, your local garden center might have offered a maximum of 12 different annuals, known then as “bedding plants”. From those 12, you would make your selections, plant your annuals, and wait for them to bloom. It was formulaic, it was predictable, and it was easy to follow without negotiating different types of flowers, growing habits, and needs. In exchange for all the choice we get to explore and be creative with now, we have to be a bit more involved in our gardens.

With a wider selection of plants to choose from to fit our every need, we have more variables to balance. In creating our perfect aesthetic, we keep in mind how aggressive our plants are or how much water they need to pair plants successfully. Sometimes our “perfect look” calls for pairing some mismatch plants, like meeker and slower growing Marigolds or Snapdragons with much more aggressive Verbenas or Petunias. This doesn’t have to rule out matching them though, you’ll just need to keep your trimmers ready to save your passive plants from getting consumed by the stronger growers. Trimming back and taming your annuals opens up new pairing possibilities to create a container that is absolutely perfect.

Reason 3: Get A Response:

Pruning your plants gets them angry and ready to grow back with more conviction and a vengeance. Your annuals are like a champion boxer – they more you try to knock them down, the tougher they get. If you trim off a quarter of their growth a couple times a year, they come back bigger, stronger, better, and more gorgeous. You get to trim off any unsightly dead growth, only to be rewarded by even more stunning growth! This method works best on plants like Petunias, Pansies, Calibrachoas (Million Bells), Bacopas, and most foliage container plants.

Simply pinch back the foliage and give them a healthy dose of fertilizer to fuel their comeback growth. Check back in a week and you’ll be delighted to see that your plant making a comeback filled with stubborn growth and blooms.

Pictured below: Snapdragons 

Keep in mind that this isn’t a one-size-fits-all-annuals method, as some won’t respond well to being hacked back. Anything with a central blooming stem (like Canna Lilies, Snapdragons, Begonias, or Marigolds) won’t make a comeback in the same way or nearly as quickly. Don’t let them go to seed, as they’ll stop blooming, but don’t be quite as aggressive with the scissors on these plants. They still need your guidance and some trimming to be egged on to keep growing and blooming for our enjoyment, just in a gentler sense.

We can sometimes be a little nervous to take a generous snip off of the gorgeous annuals we’ve adored watching bloom all summer. Just as our kids need haircuts before schools reopen in the fall, a haircut is often exactly what our favorite hard-working plants need to come back stronger. Taking charge of your garden with scissors in hand is all you need for gorgeous blooms all summer and long into the fall.