Grow Mexican Petunias (Ruellia Simplex) for a Heat and Shade Tolerant Perennial

Ruellia Simplex

Beloved by many gardeners for its heat tolerance and shade-loving nature, but reviled by others for its eagerness to spread with abandon, R. simplex can be divisive.

Thanks to its sweet purple flowers, however, we come down firmly on the pro-ruellia side of the debate.

With forms tall and short, this evergreen, herbaceous perennial – suitable for growers in USDA Hardiness Zones 8-11 – deserves consideration for inclusion in southern gardens.

The tall version forms clumps 18 inches across, while the short type forms 12-inch clumps.

Close up macro photos of two violet Mexican Petunias (Ruellia Simplex) flowers.

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It’s an erect, often-multi-stemmed plant with dark green, droopy, slender, and long leaves.

It’s especially loved for its papery, trumpet-shaped flowers that mimic every shade of the purple rainbow, as well as white and pink.

Sadly, each lovely flower lasts just a day. But fret not – the plant produces a succession of profuse two-inch flowers daily from spring through fall.

Let’s learn more about this lovely but divisive plant, and why Floridians want nothing to do with it! Here’s what we’ll tackle in this article:

If you live in Florida, you’re certainly excused from reading this article, though you might want to check below for a cultivar that is safe to grow in your region.

Or perhaps you’d like to learn about growing turmeric, which also does quite well in the Sunshine State.

A horizontal image of the tall variety of Mexican pansies used as an edging bed for a stone pathway.
Ruellia simplex can be grown in either the shade or full sun, and is great for edging or mass plantings.

Interestingly, the stem of this plant becomes more purple when it’s in bright light, as opposed to when it’s grown in a shady area, where the stem stays fairly green.

I’ve always used my Mexican petunia as a shade plant and was surprised to see purple-stemmed ruellia on a visit to Tucson, Arizona, where it was planted in full sun.

Cultivation and History

As with so many of our favorite botanicals, this one comes with a host of aliases.

Though not closely related to petunias, many know the plant as Britton’s wild, Texas petunia, or sometimes even Mexican bluebell.

Scientifically, it’s been labeled R. brittoniana, R. coerulea, R. malacosperma, and R. tweediana, though today’s taxonomists are in agreement that R. simplex is the correct moniker.

The plant is native to Mexico and South America, and has naturalized in Hawaii and from South Carolina to Texas, where gardeners appreciate it greatly.

A vertical image of the purple blooms of Ruellia simplex mixed in with other orange blossoms.
Photo by Gretchen Heber.

Butterflies like it too – it attracts swallowtail, brush-footed, and monarch butterflies eager to enjoy the flowers’ nectar.

However, as alluded to above, it is considered invasive in Florida.

There, like a septuagenarian Minnesotan in January, it has populated freely, and the locals RUE(llia) the day it was introduced.

It has a tendency to crowd out native Florida species, and so local horticulturists strongly warn against its use.

The plant is named for Jean de la Ruelle, a late 15th- to early 16th-century French herbalist and physician to King Francois.


Mexican petunia spreads naturally by both seeds – it can spew the small brown discs as far as ten feet – and rhizomes.

Top down horizontal image of the green leaves of Ruellia simplex with no blooms.
Photo by Gretchen Heber.

You can also propagate this plant via purchased seeds, cuttings, or division.

From Seed

Sow R. simplex seeds in early spring, after all danger of frost has passed. Plant one to two seeds for each expected plant, spaced 12 inches apart.

From Cuttings

If you want even more plants – in a different part of the yard, for example – you can propagate by taking cuttings in springtime.

With a sharp, clean blade, cut a healthy-looking stem just below a node, four to six inches from the end. Strip off any leaves near the bottom of the stem, and remove the bloom.

Prepare a clean four-inch pot with a mix of perlite and peat moss and moisten the mixture. Make a two-inch-deep hole in the potting mix with a pencil.

Dip the cut end of the cutting into a powdered rooting hormone, and place the cutting into the hole you made in the potting mix.

Place your potted cuttings in bright, indirect light, and keep them moist. After roots are established, you can transplant them outside.


To divide this plant, loosen the soil around the area, and then dig around the clump you wish to excise.

Lift out the clump and, using a shovel, slice the crown of the plant into several pieces.

Place your transplants into holes the same depth as the root balls of your clumps and twice as wide. Spread the roots out in the holes.

Cover the roots with dirt and water thoroughly; continue to water well for several weeks until well-established.

Get more details about dividing perennials here.

How to Grow

Mexican petunia is generally highly prized as a shade plant, but if your summers aren’t too brutal, the plant may be able to take full sun.

It is drought tolerant, and in fact, throughout our brutal Central Texas summers, I give mine nary a drop of supplemental water and they do just fine.

However, the plant does even better in wet conditions (hello, Florida!).

A close up vertical image of Mexican petunia lineing a brick wall along a waterfront in a park-like setting.

As with most plants, you’ll want to treat them to regular, deep waterings immediately after transplanting, which you’ll do in springtime, and then you can back off the watering if you like.

You can baby the plant with rich compost or you can stick in the native soil that’s already there, and it will still do fine.

Fertilize with a 10-10-10 (NPK) mixture in springtime. Or don’t. See a theme here?

Growing Tips

  • Don’t plant in full sun if the heat is brutal where you live
  • Give the plant extra water right after you plant it
  • Plant in sun or shade

Pruning and Maintenance

Trim out any dead leaves and remove dead flowers for aesthetic purposes. Cut off the seed pods if you don’t want the plant to spread its seeds.

You can dry and save them for planting elsewhere if you wish, or trade with the neighbors.

A horizontal image of a clump of the tall purple variety of Mexican petunia grown as a clumped panting along with orange latana flowers.
Photo by Gretchen Heber.

Of course, if your R. simplex spreads too far and wide, you can excise the metastasizing plants.

Cultivars to Select

Several cultivars are available, with the distinguishing characteristic typically being flower color.

Ruellia Rooted Live Plants via Amazon

A notable and popular cultivar differs from the straight species in its height.

While most standard forms of Mexican petunia range in height from 18 to 36 inches, ‘Katie’s Dwarf’ ranges from eight to 12 inches tall.

‘Purple Katie’ Mexican Petunia

This variety is less aggressive than its taller cousins, though mine definitely spreads.

You can find packages of 50 seeds are available from Amazon.

‘Chi Chi’ is a popular pink cultivar often found at plant centers.

Floridians, if you’re still with us, you should choose the cultivar ‘Purple Showers,’ which is sterile and does not produce seed.

It can still spread via rhizomes, however.

Managing Pests and Diseases

It’s not on the menu for deer, but if these graceful herbivores are helping themselves to other plants in your garden, check out this article about protecting your plants.

R. simplex doesn’t have any notable insect pest or disease concerns to worry about, either.

Best Uses

Mass plantings of the tall type make a nice border for the back of your beds, whereas the shorter variety makes a lovely edging plant.

You also might want to use this plant to add some color to shady areas.

Mexican Pansy Quick Reference Chart

Plant Type: Perennial Flower Color Purple/violet
Native To: Mexico and South America Tolerates: Drought
Hardiness (USDA Zone): 8-11 (marginally hardy in Zone 7 with protection) Maintenance Minimal
Bloom Time: Spring, Summer, Fall Soil Type: Any
Exposure: Sun or shade Soil PH: Any
Time to Maturity 1-2 months Soil Drainage: Well-draining
Spacing 12 inches Companion Planting: Lantana
Planting Depth: 1/4 inch Uses: Tall type - borders and mass plantings
Dwarf type - edging
Height: 8-12 inches (dwarf type)
18-36 inches (tall type)
Family: Acanthaceae
Spread: 24-36 inches Subfamily: Acanthoideae
Water Needs: Consistent moisture Genus: Ruellia
Pests & Diseases: Spider mites Species R. simplex
Attracts: Butterflies (swallowtail, brush-footed, and milkweed) and hummingbirds

Purple Power

Floridians notwithstanding, gardeners in the southern United States would do well to add this purple-blooming beauty to their gardens.

A lovely tall plant for the back of a bed, or a pretty edging for the front — one species, two practical uses.

Virtually maintenance-free and pest-free, and requiring hardly any attention, R. simplex is a lovely addition to any garden.

Are you in the pro- or anti-ruellia camp? Share your experience with this pretty plant in the comments section below.

And for more information on plants that thrive in the shade, check out these guides next:

Photos by Gretchen Heber © Ask the Experts, LLC. ALL RIGHTS RESERVED. See our TOS for more details. Product photos via liveplantflower, SVI, andlvrgarden. Uncredited photos: Shutterstock. With additional writing and editing by Allison Sidhu.

About Gretchen Heber

A former garden editor for a daily newspaper in Austin, Texas, Gretchen Heber goes through entirely too many pruners and garden gloves in a year’s time. She’s never met a succulent she didn’t like and gets really irritated every 3-4 years when Austin actually has a freeze cold enough to kill them. To Gretchen, nothing is more rewarding than a quick dash to the garden to pluck herbs to season the evening meal. And it’s definitely time for a happy dance when she’s able to beat the squirrels to the peaches, figs, or loquats.

126 thoughts on “Grow Mexican Petunias (Ruellia Simplex) for a Heat and Shade Tolerant Perennial”

    • Hi Cathy! Yes, they do bloom a lot, don’t they! I like the leaf form, also. Do you have these in your garden?

  1. I broke off a few sprigs from a neighbor’s stand of Mexican petunia about 20 years ago and rooted them in water. I now have a massive border of my own that blooms continually spring through late fall in the South Central Texas sunshine. No special care needed. I’m going to have to cut it back and dig some out to keep it in bounds…it goes where it wants. Hummingbirds love it.

  2. The first cold front hit Dallas (mid-October ) – so mine just finished blooming for the year. They also attract bees and it’s entertaining to watch them crawl down into the flowers and disappear. Also we grow ours by the pool so the majority of the daily flowers that fall out will float in the pool and stay purple for a few hours – so pretty.
    One question – after they have died off in the winter – do you pull them up or cut them down – what’s the best method to get ready for the spring?

    • Hi bbkahlich! Thanks for reading. I know… can you believe our crazy weather? In Austin, I do nothing to mine for winter. Once in a great while, they freeze to the ground, but then come back in spring. But mostly they just sit there all winter, looking fine. No flowers, but the leaves are fine. I can picture the blooms in the pool, btw! Sounds beautiful!

    • We are fortunate to have a beautiful array of them in a small patch of dirt outside our apartment in Dallas that is maintained by a lawn crew. It gets morning sun and afternoon shade facing the east. And in this climate, we typically see the greenery fade to brown twigs for the really cold part of the year, but the greenery lasts really really far, I’m pretty sure to November or more. And for two of the past 3 years, the lawn crew took the weed whacker to em until they were nothing but 4-6 inches of brown twigs. And one of the years they did nothing and left it all winter. In all 3 cases, the plant rebounded just fine in the spring! It is right in the location the water drains off the roof, and I have very occasionally watered it during long droughts, and also I’ve experimented with sprinkling my coffee grounds on it as a way to fertilize and avoid generating trash for the landfill at the same time… but it seemed to do fine no matter what I did, even in drought, lol. I hope this information helps! I have a *terrible* brown thumb, so this Mexican ruellia has been a sheer joy! I’m taking cuttings when I move – fingers crossed!

    • I have them in a front landscape bed, in Central Arkansas. Location is facing east with strong sun in the summer until about 2-3 p.m., then shade from the house. Mine die off (above ground) in winter, so I cut the woody stem to about 2″ and cover with mulch. They come back in early spring, and boom all summer. I’ve recently taken some of the ‘volunteers’ and put them in large pots in the backyard. They bloomed the same week that I transplanted them, so definitely hardy!! My favorite plant!!!

  3. I wasn’t a fan of these because the former owners of my house planted them as a patio edge, and I think they look awkward there. Now that I know they can live in shade, I’m going to dig them up and move them to the shade garden I’m putting in! Yay!

  4. I have a ground cover that I must keep tamed. Can I plant these in them here? The ground cover is around my tree in a shaded area of course.

  5. I got a pot of Mexican petunia in the spring. I have kept it in a large pot on my sunny back patio. It has produced only one bloom!That was yesterday. What have I done wrong? I live in NC. We’ve had a hot summer.

    • Barbara, that sounds frustrating! The pot gets a good 6 hours of sun a day? You might need to add a phosphorus-heavy fertilizer and see if that increases blooming

      • Same here with me. I live in TN and get less than 10 blooms a year. It gets sun for around 6 hours a day. I will try the fertilizer and see if it works.

  6. We have planted them in a flower bed and they are getting tall. Is there anything suggested to maybe braid them? They just look straggly. Should we braid them? Cut them back/down? The flowers are pretty but the plants themselves are spindly. Suggestions? Thank you!

    • Petty, did you plant Katie’s dwarf, and they’re getting tall and spindly? Sometimes older Katie’s will get like that. Or do you have the regular, 1- to 2-foot tall ruellia that are looking less than fab? How much sun do they get? Could be yours are needing more?

  7. I am new to your site. I was wondering why I have such a lack of growth with this plant (no spreading). I moved from DFW to East Texas with just sand as my “pretend” soil. I brought divisions with me and planted them with compost and watered weekly. I love this plant especially for the pollinators; any suggestions? I have no problem with them naturalizing.

    • Doug, welcome to Gardener’s Path; we’re always happy to have new readers! How long have your transplants been in the ground? Did you plant the ruellia or the dwarf type? Did your plants just not shoot up at all? Or they’re just not spreading? They can take a few years before they start really spreading. Hahaha regarding the East Texas soil, btw. It can be quite a challenge!

  8. After the frost has killed the plant….how do I care for them? Do I cut them down? If so, how far down? This is the first time that I have had these plants. Thank you!

    • Mike, that sounds like a frustrating situation! There are commercial weed killers available, but I would be nervous using those near the ruellia. You might just have to use good ol’ manual labor and pull them out!

  9. Hello! I live in the Pacific Northwest and I purchased a Mexican petunia a few months ago along with several other nine inch houseplants. I wonder if it was placed in the wrong area because I assumed it was a houseplant. It was beautiful and soon bloomed lots of purple flowers for a few months and then started to dry, then started to look better and grew some new green leaves, but recently has turned brown and soggy and just a few little green leaves left. I want to keep it alive! Any ideas of what went wrong?

    • Judy Ann, how interesting that you’ve been growing it as a houseplant! I wonder if you’ve given it too much water? They’re very drought tolerant.

    • Hi Adrienne! I cannot say I am an expert on elephant ears, but a bit of quick research indicates that these plants are heavy feeders and like rich soil. They also appreciate a dose of 20-20-20 fertilizer monthly.

  10. I live in No. Florida. These started growing along my drive way, I like them there, but notice they are trying to spring up across my driveway, into the lawn. Any tips for keeping them over by the driveway? So far I’ve been hand pulling the ones in the lawn.

  11. When I purchased my plant it has beautiful purple flowers. Now it only produces white flowers any suggestions on how to help it bring back the purple flowers?

    • Do you know which cultivar you planted, Kimberly? Is this in fact the same plant, or new offspring that grew from last year’s seeds? Are your white flowers still purple or pink in the center?

      Though there are sterile varieties out there, most self-sow readily – and not all types are true to seed. It sounds like you planted a purple type that was pollinated, and the seeds that developed have slightly different genetics than the parent plants – with white flowers instead. If this is the case, unfortunately you won’t be able to make them revert back to purple.

      This has actually been studied in a lab setting, and the authors of a study of flower color in Mexican petunia published in the Journal of the American Society for Horticultural Science concluded that “the inheritance of flower colors in R. simplex can be explained by the inheritance of anthocyanin pigmentation, which is controlled by multiple genes…”

      On the other hand, if they are more of a pale lavender rather than being truly white, this could be a case of receiving too little sunlight. Purple cultivars produce the most vibrant blooms in full sun.

  12. We moved to SW FL from Northern California with its red rocky soil going on 2 years ago. Now it’s very sandy soil and I think nutrient poor. My husband brought me several purple Mexican petunia plants from a neighbour and another neighbour who unfortunately moved away gave me some pinks (which I adore). I happily yank and transplant often and they are so hardy. Yes they spread but I love how they show up in the craziest places. My landscape garden is close to 2 years old and I still love these pesky petunias. I poke them in the middle of a native Honeysuckle and the pop of purple looks so bright and cheerful. I mix with firecracker bush and moved some pinks to the base of a white bird of paradise. Love,love, love RUELLIA

  13. I live in florida and love these plants for the color and height they bring to any area of the yard. Would love to have the white but have never seen them.

  14. Do NOT BUY AND PLANT this crap in your yard, it spreads, its taken over almost half my backyard. It’s a nightmare. The small flowers last a day.

    • Hi Tommy –
      This is indeed a vigorous grower with invasive tendencies that may not be appreciated by all. Thank you for sharing your thoughts.

    • Tommy, I’m not sure where you are, but if you are in Florida where it is a big problem I suggest try the Florida native Wild Petunia instead. It will not spread by runners, but does spread by seed. The benefit is the native petunia will feed our native birds and bees, where the non-natives usually do not. This is becoming an increasing concern as our bird, bee, and native insect populations diminish.

  15. When do I transplant? Mine has too much shade, I’m wanting to move to a sunny ???????????? spot USA, Tennessee.

    • Hi Diane –
      While it’s best to transplant in the fall, you may move it now if necessary. Hydrate the plant the evening before you move it. The next morning, before the heat of the day, dig it out and transplant it. A plant that is moved during the growing season experiences more shock than one that is moved as it’s going into winter dormancy. After transplanting, be sure to maintain consistent moisture. Expect it to take some time to bounce back.

  16. Planted a couple at the back of my house in the Tucson, Arizona sun and heat and much to my surprise, they are spreading and making a very boring area start to look good!

  17. I didnt really notice the undergrowth until one day, then I gently removed it but found gaping spaces. I also found that the ruellia crawled along the ground to survive and attached roots along the way. This has made this part of it brown. When i dislodged this part to get them growing right again, I found them to be too long to stand up straight on their own. I have bought more plants for the gaps. How can I remedy the long ones? How can I get them to stand up again? How should I prune them? How do I remedy the brown stem part?

    I’ve also attached a picture of the culprit who has taken over all the real estate, choked the ruellias and forces them to crawl along the ground, grow new roots and become brown.

    Thank you in advance for your help.

    • Hello Gwynne –
      Thank you for including photos of your Mexican petunia. This is a vigorous grower that does get woody brown stems. With deep pruning in early spring, plants will be more erect and creep less.

  18. I love the plant! Planted a couple babies in my mother in law’s garden where she wanted something beautiful and easy to care for. They started growing and flowering and then she said to get rid of them. Found out they are invasive. Very disappointed!!

  19. Hi! I live in GA and have these beautiful flowers! However, this morning I noticed that the tops of mine were all eaten off. At the same height. Any suggestions what could have eaten them? I’m in a subdivision so I doubt a deer wandered in. The tops of a few of my vincas were also eaten off. And feedback would be great!

    • Can you see any bite marks or small holes on what remains of the plants? Besides larger herbivores (which sometimes like to munch on these, but more often than not, they will pass them up in favor of other options), caterpillars will also eat Mexican petunias, and several species of butterflies use them as a host plant.

  20. Ours bloomed it’s first year, just beautifully. Now no flowers. Well maybe one or two. It’s in full sun. Anything I can do to encourage flowers? Thanks.

    • Is your plant crowded at all? If so, you can encourage it to bloom by dividing or thinning it. If it isn’t crowded, you may want to do a soil test to determine if you’re low in any of the macronutrients (nitrogen, phosphorus, potassium). Soil low in phosphorus, in particular, can cause plants to not bloom.

  21. Hello Gretchen. Could Mexican Petunias be grown as an annual in the north (zones4/5) and would they have time to bloom if grown from seed? Or maybe could they be started earlier indoors and moved outdoors? Lastly, maybe even grown in pots in the ground and moved indoors before frosts?

    • Yes, you can absoultely grow Mexican petunias as an annual in northern regions, even from seed, as long as you have 3 good months of frost-free weather (as zones 4 and 5 do) and a spot in full sun. You can also start indoors 8 weeks before the last frost if you want to have blossoms earlier in the year. If you want to grow them in containers, that’s an option as well. Keep in mind that they can get large, so you’ll need to increase the size of the container up to at least 18 inches wide and deep when the plant is mature. You could also plant a dwarf variety, and then you can use a much smaller container.

  22. I live in Frisco, Texas.
    My neighbor brought this Ruella from South America.
    The stone pillar in the background is over 6 feet!!

  23. Is anyone gonna mention that invasive plants are harmful to our ecosystem? It’s not just that some Floridians “don’t like it”. It’s that its crowding out our native plant species and harming the environment.

  24. I live in southern Ohio and purchased this at Home Depot. It had a tag saying plant outdoors but move it indoors over the winter. But you could leave it outdoors if you put a heavy layer of mulch on it and it would rebloom in the spring. Is this true?
    I would like to leave it outdoors but dont want to kill it. It’s so beautiful.

    • I’m afraid southern Ohio is probably a bit too cold to winter this plant outdoors, even if you give it lots of mulch/protection. To be safe, I’d definitely winter it indoors. I’d err on the side of caution, because you’re right, it’s too pretty to kill!

    • We grow these in west central Ohio. One year after a mild winter they survived. Other times they have died. We bought a plant in NC last autumn and we divided and rooted them over the winter for outdoor planting. They have dine great and it is so nice to have a plant that is not in everyone else’s garden!

      • That sounds like a quite reasonable approach, Jihn. Whenever possible, I like to propagate cuttings from flowering plants that respond to that approach. That way, you have ’em if you need them and can share them with someone else if the parent plants make it through the winter.

  25. I’m in the pro camp. Love this beauty. My 4-year-old (at the time we planted) granddaughter got a small cutting from her Sunday School teacher. She wanted to plant it at Grandma and Papa’s house. She picked a spot right by the steps leading to our front porch. Papa dug a hole and stuck it in the ground. My granddaughter watered it. That is absolutely all the attention it received. My husband did cut it back to the ground each winter and every spring it would come back bigger and better, blooming those lovely purple blooms. It has been in the ground for 10 years now and yes it has spread a little but not invasively. Everyone compliments us on how pretty it is and it stays beautiful from early spring through the fall until the heavy frosts become frequent enough to stop the blooms. It still stays green for awhile longer. When it turns brown my husband cuts it back to the ground. Picture attached. We live in SC.

    • Thanks so much for sharing this beautiful family gardening story, Martha! I always enjoyed gardening with my grandparents as well, and learned so much from them.

      If you wouldn’t mind, could you try uploading your picture again? It doesn’t seem to have worked the first time around (sorry about that!).

  26. Hi – I’m not sure I like this plant. We planted them as a border in our front garden and they completely took over. I am trying to dig them out – do they have root stems with a sort of garlic looking bulbous growth on the stem? They are pretty but we don’t want the whole garden covered by them. Thank you!

    • You’re right, they can get aggressive in the right conditions. The roots are thick, several-inch-long rhizomes, but they don’t have bulbous growths on the stem. Deadhead them and keep pulling to keep them under control, or you may want to use them as a container specimen instead.

  27. Gretchen,
    I am new to this site, however you seem to be very helpful. I have had this plant for many years and it is beautiful. It’s in our pond as a centerpiece. It’s about 3′ tall and has bloomed every day – until 4 months ago when it just stopped. What is going on? I miss my flowers. I would be grateful for any help understanding what happened.
    Vickey in Katy, TX

    • There are a few things I would check. First, it could be that as your plant has grown this year, it has gotten too crowded. Try thinning it out if that’s the case. Second, have you applied any fertilizer? If the plant is getting too much nitrogen, it may stop blooming and will start to focus on leaf growth at the expense of the flowers. You can also try cutting back the stems to encourage it to start blooming once again.

  28. Love the Mexican petunia. Have several large pots outside. I am in Lake Charles, LA. This year there are no blooms. I used Osmocote 15-9-12. I put them in pots to control the spread. The foliage looks good.

    • Fertilizer formulas such as this one that contain more nitrogen (N) than phosphorus and potassium (P and K) can lead to lush, leafy growth with few flowers.

  29. I love these Mexican Petunias. I am a realtor in Florida and have several out of state investors who buy/own duplexes or small SFHs and most of the time the garden beds are empty or weeds so I always tell them to plant a couple of these plants and within a day (if you buy them a foot tall or so) or even a few weeks if you buy them smaller, their gardens will be colorful, and the tenants do not have to take care of them because they take care of themselves basically.
    They have brightened up may lower priced rental properties and made them shine!
    Cheap too.

    • Barbi, please encourage your homeowners to plant something native instead, it will help our local birds, bees and insects. The Mexican Petunia is classified as a Category I Invasive in FL due to its tendency to get out of control and be very difficult to eradicate. So, it is actually not maintenance free since if they are not kept in check (with constant pulling of the root system, not just the portion of the plant above ground), they will spread everywhere there is not a paved surface.

  30. Love my Mexican petunias but the leaves are turning yellow. What’s wrong? They are planted in shade and receive plenty of water. 🙁

    • It sounds like this could be a nutrient deficiency, Janice, or perhaps a case of overwatering. Are they planted in the ground or in containers? Is the soil well-draining? And have you fertilized them recently?

      • They are in the ground. I watered them when I got them and the rain has done the rest. I’ve had them about 45 days and no I have not fertilized them.

        • These plants are drought-tolerant once they’re established, but it’s a good idea to baby them a bit if they’re recent plantings. Be sure to give them supplementary water during periods of hot weather, and see if they perk up. Both overwatering and underwatering can cause yellow leaves. You might also want to do a soil test, to determine the nutrient makeup of your soil and see if any amending with fertilizer is called for. Good luck!

    • I live just north of I-20 around Atlanta and yes, mine survives very well. They are not blooming this year but have read that they might be too crowded. Mine did very well blooming the first 2 years so guess they are crowded so will thin them next spring.

  31. Hello I live in Florida and my problem is they will not stop growing. I cut them back and within a month they have grew back over the fence in the front yard. Thanks to my mom that has a super green thumb these beautiful purple petunias are about 4ft tall and 6ft wide in growth. She is 84 and wants to sell them. Please help they have taken over the front and side yard.

    • Oh, Vei Sprad, too much of a good thing, huh? I love that you were trying to help your green-thumb-gone-wild mom. But I’m afraid cutting them back only encourages them.

      Mexican petunias grow both from seed and those thick, short roots that grow sideways, called rhizomes. So to get them under control you’ll need a three-part approach:

      1. Pull up as many as you can. Pull them all the way up, roots and all, and dispose of them.
      2. Deadhead the spent flowers before they can produce seeds, or cut off the seed pods before they burst open and reseed on all available ground.
      3. Repeat steps 1 and 2.

      If your mom wants to sell them, it would probably be best to grow them in containers where they can’t spread like crazy. In Florida, as mentioned above, they are considered an invasive species.

      Let us know how it goes. I’m rooting for you!

    • Hello Sandy Hall! I am hoping this is an easy fix. There’s a decent chance that they need thinning to get back to blooming. I also want to make sure you haven’t applied a nitrogen-rich fertilizer this season. That encourages them to produce lush leaves and few or no blooms. And I feel like the sun was probably okay, since they’re not particular about that, but it shouldn’t hurt them to be in a sunnier spot, either. If you don’t mind, it would be great if you’d check back in and let us know if you were able to fix the problem. We all need more purple in our lives!

  32. I live in Southwest Oklahoma and I absolutely LOVE my purple Mexican petunias. They do great in my area and the hummingbirds love them. It gets cold enough during the winters that they die back but every spring they come back bigger and better. I have some along my front fence, some in a front flowerbed, and two very large pots on my back porch and all have done just great.

    • Hello Donna. Thanks so much for sharing your positive experience with Mexican petunias! It’s particularly good to get first-hand verification that they are appealing to pollinators and hummingbirds. Feel free to show us some photos!

    • More to love! I’m curious, though, are they young kids or adults? I’d like to know if Mexican petunias are a good option for kid gardeners…

  33. I’ve been a huge fan of these beautiful purple flowers for years. I had them in Florida and now Georgia. Simply so easy to grow & so nice to look at. I have both high and ground cover. Also easy to re-root, just cut and leave in water, you have nice roots in 2 wks or so. So if you’re new to your garden, try these – you will be successful!!

    • Hello Deb, and thanks for the encouraging words. I love anything that’s easy to propagate. To me, that makes it so you don’t have to worry as much when you decide to prune or transplant, since you can always take some cuttings first and have them as a backup if anything goes wrong.

  34. Hi.
    There is a white growth all over my Houston ruellia — on the tall and the dwarf. Never saw it before, but I see it in other yards. It is not infecting other plants. The ruellia is actually easy to pull out now. It goes into major decline. I am pulling it all out.

    Do you know what this is? Is it a blight?

    • I’m glad you shared that photo, which allows me to see those white spots are probably not powdery mildew and don’t need a fungicide. I think this Mexican petunia has an “erineum,” which is a fancy term for “odd growth pattern.” The cause is the eriophyid mite (Acalitus ruelliae).

      And I do think you’re doing the right thing: Getting rid of the affected foliage without getting worked up about it. The plant will probably be fine without any extra TLC.

      Just as a precaution, if you do have stems without the white spots, I would propagate a few since it’s so simple. That way you’ll have a backup if these plants do succumb–but I wouldn’t anticipate that.

    • Hello, Sue! When you’re trying to get your Mexican petunia to grow fuller, it’s a great idea to prune the heck out of it.

      The best time is in later fall, after the first frost when the stems were going to freeze on their own anyway. When you notice the stems are brown, use clippers or a clean, sharp blade (be careful!) to cut the Ruellia to two inches tall.

      Then it will sprout anew in the spring. Gardeners who don’t have freezing winter temps in their area should do this pruning after the blooms have fallen and the stems have turned brown.

      And note, if you’re trying to get a sprawling, spreading Mexican petunia under control, pruning will only encourage it. You’ll need to uproot the rhizomes and toss or compost them to stop the aggressive spreading. 

  35. Hi Gretchen. I live in northeast Florida and planted a couple of Mexican Petunias along a fence section. A lady at Lowe’s, where I bought them, warned me not to buy them because they would take over my yard. So I only bought two to give them a try. Exactly how long does it take for these things to “take over?” I planted these in the spring of 2018 and they have gotten taller and wider, but I don’t see them taking over. Maybe I have the kind that doesn’t produce seeds because I haven’t seen any pop up anywhere else (like other plants have done, which I personally think is pretty cool.) They have spread a little in place, probably from rhizomes, but they definitely aren’t taking over my yard. I love them and am wondering if I’ve waited long enough to see if they would take over before I plant more along the fence. I have cut them back 2 or 3 times since I planted them just to keep them fuller instead of leggy.

    • Hello Kathy Willey!

      I’m glad you’re fond of Mexican Petunias and that they haven’t been too aggressive. I’m wondering if you have the shorter version, which only gets about 12 inches wide or tall?

      I’m sure they’re producing seeds, but maybe your pruning is keeping them from spreading far and wide? Sounds like you’re happy with the shape and size, though, so I’d keep doing what you’re doing and plant a few more where you want them instead of leaving it to chance that they’ll start taking over.

      Since you like the ones you have (even if they’re not doing that cool thing of sprouting here and there around the property), I would suggest propagating cuttings from your own plants.

      Gretchen has already provided great advice in that area, so I’ll leave you with an excerpt from her coverage, and my wishes for the best of luck:

      If you want even more plants – in a different part of the yard, for example – you can propagate by taking cuttings in springtime.

      With a sharp, clean blade, cut a healthy-looking stem just below a node, four to six inches from the end. Strip off any leaves near the bottom of the stem, and remove the bloom.

      Prepare a clean four-inch pot with a mix of perlite and peat moss and moisten the mixture. Make a two-inch-deep hole in the potting mix with a pencil.

      Dip the cut end of the cutting into a powdered rooting hormone, and place the cutting into the hole you made in the potting mix.

      Place your potted cuttings in bright, indirect light, and keep them moist. After roots are established, you can transplant them outside.

  36. I live in the northern suburbs of Dallas, and my 4-foot tall plant was damaged by this recent frigid weather snap. Can I prune the plant this early in the year.

    • Sorry to hear it, Diane! It’s actually best to wait until the return of consistently warm weather to prune frost-damaged plants. Keeping the damaged foliage in place will serve as extra protection, even though it doesn’t look particularly attractive.

  37. I like your style!!…Love the article! Appreciate the Advice for the S. Florida area 10 gardener !! Anything on Lavender??

  38. “Don’t plant in full sun if the heat is brutal where you live” My Mexican Petunia begs to differ with that statement! It is planted in full, south and west Phoenix sun and doesn’t even wilt when we go over 115°. It’s now standing at a lovely 5’ tall and has developed a woody base (I braided the base stems as they grew and trimmed year after year to take on a bush-form). This is by far the hardiest plant I have ever owned! Wish *I* was as hardy in the scorching Phoenix heat. Thanks for the very informative article!


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