Updated on July 27, 2024

Trimming back plants after they bloom can often yield a second bloom to enjoy this growing season.

Here’s a question I received about it:

BBD: “Wondering [do] you accept requests for content? I need help growing herbs. My dill and cilantro quickly go to seed and my basil gets attacked by bugs.”

Me: “Hooray, somebody’s out there!”

It’s great to receive input, especially when that input includes ideas for posts. Comments, feedback, likes, hearts, give assurance that someone is actually reading this.

So, here’s today’s gardening question:

How do you rejuvenate the garden after the heat and drought of July?

Trimming Back Plants

It’s important to trim many garden plants as the growing season continues.  Whether you call it “deadheading,” “pinching,” “trimming,” “cutting,” or “cutting back,” think about what your goal is, and then you’ll understand what to do.

I remember watching a friend as she pulled faded petals off her flowers and told me that the plants would be more likely to re-bloom because she did this.

When I started gardening, I did the same.

My petunias still looked awful by the end of July. They had long, stringy stems with yellow, dry leaves and only one or two blooms.

What was I doing wrong?

Getting to Know Your Favorite Plants

Understanding the life cycle of plants helps guide your work.

It can be confusing because there are all kinds of plants (woody, herbaceous, annual, perennial, biennial) with different flowers (single, compound, racemes, umbels, panicles).  Unless you’re going for a botany degree, do you really need to know all this?

Can you just use common sense?

Of course you can.  Think of it this way.

Nature’s goal is to keep life going.  So, once a living thing successfully reproduces, it has served its purpose.

Applied to the garden, this means that once a plant has produced seed, it doesn’t need to expend energy on anything else. It’s done.

You cut back plants to keep them from being “done.”

What was I doing wrong by picking the dead petals from my petunia plant?

I was only making a cosmetic change.  Pulling off dead petals didn’t stop the plant from producing seeds. The part of the flower that makes the seed was still on the plant.

The goal is to cut the plant to prevent seeding. This will stimulate the plant to grow and rebloom.

Where to Make the Cut

Not all flowering plants have multiple flowers on stems, or leaves growing on the stem. Some flowering plants won’t re-bloom even when cut back.  However, most of our favorite summer annuals do:  petunias, marigolds, and zinnias.

Trimming Back Plants with Short Stems

If your aim is to get more flowers, you should cut below the calyx (the special little leaves that make a cup for the petals, where the flower attaches to the stem).

In the petunia photo below above, the red line shows where to cut.  There are so many blooms and buds on this petunia plant, it doesn’t make sense to cut further down the stem.

Trimming Back Plants with Long Stems

If a plant has a long stem supporting one blossom, cut the stem all the way down to the next node (the part of the stem that looks like a bump, where leaves grow out).

I removed many ox-eye daisies in the spring, but a few plants were left in the bed.  These remaining plants grew much lower, so I’ll cut spent blooms back to the last (topmost) node on each stem.  In the photo below, the red circle shows where I will cut.

Many perennials, like nepeta and yarrow, will rebloom if cut back.  Because they have so many blossoms, you’ll probably just cut them with garden shears, rather than looking carefully at each stem for a node.

No Blooming Cuts

Daylilies bloom on long stalks  with multiple buds. 

If you Google “deadhead daylilies,” you’ll find a fairly even division of advice between yes and no.

Pulling off the spent petals will make the plants look neater.  But, as we said above, it won’t prevent seeding, and it won’t stimulate new growth.

When pulling off dead daylily petals, I’ve almost always knocked off new buds by accident.

 Another problem with removing dead petals on dark colored daylilies is that the petals tend to seep their color and stain my gloves and clothes.

So, my advice is to wait until all of the blossoms have finished before cutting back the stalk.

 Let’s Talk Herbs

Many herbs are perennial. We use their leaves for flavoring.  Mint, oregano, thyme, chives, and tarragon are examples.

You may choose to cut the flowers off of these herbs, but whether you do or not, they will continue to grow and produce new leaves during the growing season.  Cutting these perennial herbs back will give you bushier plants that you may find more attractive.

Cutting back will also stimulate new leaf growth, and new leaves seem to have a better taste and texture.

Other herbs are annuals, and cutting them back won’t necessarily prolong their growth.

Basil, Dill, and Cilantro

When it gets hot and dry, basil loves to send up flower spikes. Those flowers attract its pollinators, bees.  Once the flowers have been pollinated, the plant sends it energy into producing the seeds that will ensure continuity of basil in nature.

That’s how most flowering plants work.

We want basil, dill, and cilantro to keep producing those lovely, fragrant leaves.

To keep these annual herbs from going to seed, you can try cutting back as was discussed above.

However, these herbs are “true annuals,” which means that they are adapted to go to seed at the end of their season, no matter what you do.

You can delay the process a bit by cutting back, but these plants are sensitive to daylight hours, temperature, and time.  Their “nature” will win in the end.

For dill and cilantro, commercial growers start new seedlings to replace those that are nearing the end of the life cycle.

 Basil will keep growing until the first frost, so make some pesto and continue to enjoy the fresh leaves.

Here in Ohio, we have just finished a round of blistering heat. You can feel a change in the air, and you can hear it.  The low chirp of crickets in the late afternoon, the sun rising a bit later, the most stressed foliage beginning to lose its green.

Working with nature is the path of least resistance.  Isn’t it nice to know that even nature recognizes when we need a rest!

Wondering about some of the flower vocabulary on this page?  Here’s a webpage of illustrations (link here).

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