Getting the most from your Volcano phlox

Easy care Volcano phlox can provide months of color with very little care.  Here are a few tips for getting the most from your Volcano phlox.

Volcano phlox with butterfly

Volcano phlox are real butterfly magnets!

adding color to fall gardens

Volcano phlox adding loads of color to a late summer garden

Plant spacing

Phlox and other perennials need space for the air to flow around them a bit and Volcano is no exception. If your plants have multiplied over the last year or so, divide them so that there’s at least 16-20 inches between each plant to help their natural tolerance to mildew. Volcano phlox are generally more compact than other phlox but it’s not unusual for a single plant to develop 15-20 stems, providing loads of blooms.

Pinching back

To get staggered and longer flowering times, you can pinch back either a portion of a single Volcano phlox plant, or if you have multiple plants you can pinch back some plants while leaving others to grow. Simply cut or pinch back each stem by about 2-4 inches.  The pinched back plants will flower a little later than the others.

Some garden designers suggest cutting your phlox back at an angle, cutting back the lowest on the front branches and then moving up and back in diagonal manner.

volcano phlox

This Volcano phlox was pinched back to create a staggered bloom cycle

Volcano phlox

Here are the Volcano Ruby with their staggered blooms. The plants in the foreground were pinched back early in the season, and are blooming slightly later than the ones in the background


Because they’re such prolific bloomers, Volcano phlox need to be fed well, preferably with a time-released plant food or a general flowering plant food. Feed in early spring and then throughout the season for optimal blooms and plant health.

Deadheading for multiple bloom cycles

Unlike many phlox paniculata, Volcano phlox will re-flower several times throughout the growing season if deadheaded (blossoms cut off after blooming). Here in Vermont we often get 3 bloom cycles, starting in mid-June and lasting through the first heavy frost.

Volcano phlox

These Volcano phlox are ready to be deadheaded. Shortly after they are, they’ll send out new flower heads!

 Volcano in the garden

Volcano phlox make great garden companions with daylilies, ornamental grasses, Sedum Autumn Joy, coreopsis and other perennials.  If you like single swaths of color, plant Volcano Pink with pink echinacea/cone flower, pink dianthus, Flower Carpet Pink Supreme, and perhaps some pink annuals like geraniums or begonias.

volcano phlox

Compact Volcano phlox mix nicely with daylilies in this cottage garden.

color in late summer gardens

Mixed varieties of Volcano phlox in a late August garden


long blooming phlox

This is the 3rd set of blooms on these Volcano phlox in late September


mildew tolerant Volcano phlox

Volcano phlox will bloom right into the fall if deadheaded.


long blooming phlox

Volcano Pink with Red Eye on it’s 3rd bloom cycle this summer! This photo was taken in late September!


mildew tolerant phlox

Volcano phlox ‘Ruby’ is blooming in late September. Just cut off spent blooms and watch for new blossoms to explode each summer!


If you’re growing Volcano phlox, we’d love to hear how it’s performing in your garden!

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9 Responses to Getting the most from your Volcano phlox

  1. Graciebelle May 17, 2013 at 3:20 pm #

    Thanks for the info on Volcano. Question – do you have to wait until the flowers are totally faded before deadheading or can you cut them back as they start to die off?

    • Your Easy Garden Team May 17, 2013 at 3:23 pm #

      Hi Graciebelle,
      If we’re out in the garden and notice that the flowers are starting to fade, we’ll cut off the flower heads then rather than waiting for them to be totally gone, but either way is fine.

  2. Lori July 19, 2013 at 12:46 am #

    I’m wanting to plant my volcano phlox in a container but need to know how big the container should be?

    • Your Easy Garden Team July 19, 2013 at 2:21 pm #

      Hi, Usually, at a minimum, it should be 18 – 20 ” wide AND deep. It can always be bigger than that. Hope this helps and have FUN with it!

  3. Catherine September 21, 2016 at 3:15 pm #

    Have you ever had blooms in mid/late September?

    • Your Easy Garden Team September 22, 2016 at 2:44 pm #

      HI Catherine, we sure have! We’ve just added a few pictures of Volcano phlox to this post and those pictures were taken yesterday in Vermont. The Volcanos were “deadheaded” after their 1st and 2nd set of blooms, and these are the 3rd round! It’s important to deadhead/remove the spent blooms throughout the blooming season. Otherwise, although you may get some re-blooms, generally you won’t get very many. Are you growing Volcano phlox and if so, do you still have blooms?

  4. Kellie Whalan March 6, 2017 at 8:29 am #

    Hi, I have 2 but one is going great but I am concerned about the other.
    Its leaves are drying and curling. It has 3 flowers and I am concerned.
    I have replanted it in new good potting mix with a topping of slow release.
    Any advise would be appreciated.
    Thank you heaps Kellie

    • Your Easy Garden Team March 10, 2017 at 2:19 pm #

      Hi Kellie, if you’re in Australia or New Zealand, it’s not surprising that the leaves on your Volcano phlox may start to look a little tired this time of year. Are all 3 in the same location? If, where ever you live you still have a few months of warm weather, you can try cutting it back to about 6-8 inches and it should send out new growth. Keep us posted!

  5. Kellie Whalan March 11, 2017 at 2:33 am #

    Thank you, I am in Gunnedah Australia (nights are getting cool & the days are still warm). I have cut 1 volcano back (the so so one, and i will see how it goes. I also have moved them into a semi shaded position where they get the sun of a morning but shade of an afternoon. They are still in pots but as soon as i can get into my place i would like to plant them in the ground next spring.

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