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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18 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?

  2. 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.

  3. 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?

  4. 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!

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

    Have you ever had blooms in mid/late September?

  6. 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?

  7. 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

  8. 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!

  9. 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.

  10. Betsy Sole May 19, 2017 at 4:47 pm #

    I live SE Michigan, and bought white volcano phlox about 6 years ago. They performed beautifully until last year when the leaves started turning yellow along the veins and then dropping. I tried fungal spray and looking for insects, but no luck. I cut them way back and cleaned up debris in the fall, but I can already see this starting again. I actually wanted to buy more of these and have called every greenhouse in reasonable distance, and even the growers. Apparently, they are not sold in Michigan. Go figure!

  11. Your Easy Garden Team May 22, 2017 at 3:15 pm #

    Hello Betsy,
    Volcano phlox are mildew-tolerant, but not totally mildew resistant, meaning that if they do get mildew, they’ll grow through it and still bloom. They need space for air to circulate around them (especially if you’re having a damp spring) so after 6 years, it may be time to divide them. You can simply cut them in half and transplant the section you dig out to anther area. If you end up breaking off part of the tops, it’s not a problem – those branches will just send out blooms a bit later. Much of the mildew issue is related to the dampness and if you’re getting the same cold, damp rainy weather than much of the northern midwest is, you’re probably dealing with a bit of mildew. We’ve found that a Neem spray seems to work well to reduce/control the mildew (it works on loads of other things too). Most garden centers carry it in multiple forms – hose end sprayer or a spray bottles, etc. If you haven’t fed them yet this year or even later after their bloom cycles last year, it’s important to do that. Because they’re such heavy bloomers,they need plenty of food to replenish themselves. A time-released fertilizer like Osmocote works well for long-term feeding but you can supplement that with a more immediate-feed fertilizer as well when they’re stressed. Please keep us posted!
    As to not being available extensively in Michigan, we’re hoping that problem will be solved by next year but you might want to check with your local Home Depot or Lowes soon. They should be on the shelves by Memorial Day.

  12. jan BEWLEY September 16, 2017 at 6:00 am #

    do they like alkaline or acid soil?

  13. Your Easy Garden Team September 17, 2017 at 4:27 pm #

    They’ll tolerate almost any soil as long as it’ well drained.

  14. Your Easy Garden Team September 27, 2017 at 4:06 pm #

    They’ll tolerate either as long as the soil is well drained. The don’t like sitting in water – can encourage mildew.

  15. Laura July 21, 2018 at 4:27 pm #

    I got mine from the store and ever since they are going down hill and fast. Not even two weeks and the flowers are drying up and leaves are crunchy

  16. Laura July 21, 2018 at 4:30 pm #

    I don’t know how to fix x them. I didn’t want to put them out doors when I got them because it was over 100 degrees outside and higher. So should I put them out now. It’s in the 80’s and going to get higher 90”s

  17. Your Easy Garden Team July 25, 2018 at 9:17 pm #

    Yes you can put them outdoors but make certain the hole in which you’re planting them is wet (fill with water, let it soak in and then fill again before planting). Then just make certain you keep them well watered but remember to water at the base of the plant, not from the top.

  18. Your Easy Garden Team July 25, 2018 at 9:18 pm #

    Have you kept them well watered?

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