Trimming Back Herbs and Flowers for Another Round of Bloom

white flowers of hosta and purple flowers of tradescantia

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!”

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

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, though they had been covered with blossoms just a month earlier.

What was I doing wrong?

Getting to Know Your Favorite Plants

Understanding the life cycle of plants helps guide your care of them.

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

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.

Single rose "William Baffin" is pure, clear pink with yellow stamen.
The last blooms of the climber “William Baffin.”

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

What was I doing wrong in 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 re-bloom.

Where to Make the Cut

If your goal 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).

Deadhead petunias at the base of the bloom
Cut the flower head below the calyx – the cup of specialized leaves (sepals) that hold the flower petals.

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.

To avoid creating a plant that looks like it was eaten by invaders, 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).

Balloon flower deadheading leaves stalks looking bare.
Cutting just below the calyx on this balloon flower can leave stems looking like they’ve been grazed by a herd. Better to cut to the first node on each stem.

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.

a yellow marigold has a long stem before a set of leaves.
This marigold has a long stem, so it’s best to cut down to the first set of leaves.

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.red circle shows first leaf node below flower head

Many perennials, like nepeta and yarrow, will re-bloom 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.

faded flowers of nepeta and yarrow
Nepeta and yarrow flowers are fading in the late July sun.

 

No Cuts!

Some plants don’t actually need deadheading.

Daylilies send up stalks with multiple blossoms, and those blossoms open sequentially.  You can pull of dead petals, but you need to use caution so as not to knock off the buds that haven’t opened yet.

20180704_095534
Daylilies bloom on stalks  with multiple buds.  You don’t want to knock off the buds, so don’t deadhead until all of the blossoms on the stalk have finished flowering.

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 cutting off dead blooms, I’ve almost always knocked off new buds by accident. So, my advice is to wait until all of the lily blossoms have finished before cutting back the stalk.

Experts say never to cut the lily stalk by more than 1/3 its height, so that the plant can continue to produce energy for its roots (rhizomes).

 

So, which plants re-bloom and which don’t?

The best thing to do is search the Internet on a case-by-case basis. There’s a lot of garden expertise available for free.

 

Let’s Talk Herbs

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

thyme has fuzzy gray-green leaves and small white flowers.
Thyme blooms mid-summer

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.

Green leaves of basil in a garden bed.
Basil has fragrant leaves that will keep growing until the first frost.

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 arrangement vocabulary on this page?  Here’s a webpage of illustrations (link here).

© 2018 auntjoannblog.com. All rights reserved. See Legalese tab for permissions.

 

 

5 comments

  1. janesmudgeegarden says:

    I usually cut the few petunias I grow ( I don’t like them very much because of their sticky leaves) with the hedge clippers into a small mound. They reward me with more flowers, so they must be grateful. I don’t bother dead heading them….too much hard work.

    1. Ha! Have a great weekend 😄

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