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Emily (who we are)

Ruellia
(roo-EE-lee-ah)
Wild Petunia or Mexican Petunia
ACANTHACEAE

Mexican PetuniaWhat a beautiful, long blooming perennial. From spring until the fall. Each flower sometimes only blooming for one day. The leaves are lance shaped, from four to six inches.

In the wild species, of the Mexican petunia it will sprawl 3 - 4 feet and grows as high as 4 - 6 feet.

The flowers are five lobed and tubular: purple with darker veins. It also comes in pink.

They bloom and then within hours or a day the bloom falls off. Ours, in Northern Florida, start blooming in late June, I think and then keep blooming all summer into the fall.

Grow in sunny to partial shade. Zone 7 - 9. Keep in well-drained soil.

They look nice in border, cottage gardens, and pots. The wild species (Ruellia tweediana) can be invasive (see warnings, below)

Mexican PetuniaPropagation

One can propagate in the fall or spring by seeds or division.

Wait 'til the pods are brown and mature and on the crunchy side. Then split the pod and take the seeds out.

Pruning

I've cut back my Mexican Petunias all sorts of ways, just to experiment. They seem to come back every time.

Our main bed is about 2 1/2 ft wide and a winding 30 feet long

Mine usually get 2 1/2 to three feet tall. They are that right now (northern Florida, end-July). If they get much taller, they fall over, grow horizontally, then up again. I've never cut them this time of the year. Only in late fall or winter.

I've cut them back by half. The next season they grow back. I've cut them all the way to the ground. They also grow back in the next season.

If they are too thick, I try to just pull them up to thin them out (it's difficult to pull the bigger ones up, but it can be done.)

I've also cut some all the way to the ground and some half way and leave the smaller ones. This is my favorite method. It does not cause the bed to look dead after I do it.


Mexican PetuniaEmily: How do I kill it?

Dear Emily: Hi, I came across your site on the Mexican petunia....... help........

I am overrun by this and cannot get rid of it.

A friend gave me one tiny little stalk years ago, we planted it, and now is huge, it has killed off all my other flowers in the back yard, and it has now started running roots under the ground and outside the flower beds and has now ruined the yard itself, and the landlords are upset and want it gone.

I don't know how to get rid of it. I tried last year and its getting worse.

We mow it down, but the roots are still in the lawn.

I have to get rid of it before the landlord has a hissy fit.

HELP !!!!!!!! What to do to get rid of it. It has spread everywhere: under the ground, up to the patio, into the lawn....

A: Doncha just luv it when somebody writes in and asks how to kill one of our favorite plants?

Since we have so much of it, we can appreciate the question. Your description of it's growth is right on.

When it spreads from one bed to another, or to the lawn, we do have to deal with it. I just wiped it out of one of our beds by pulling it. Yes, it is hard and the roots of the older plant go deep. I do not think you have to get the entire root out, but you do have to discourage it. Then you have to conscientiously follow up and pull it up again in a few weeks because it will come back or you will miss some. I was successful with this method of wiping it out of an entire bed.

I keep it out of the lawn by conscientiously pulling it. Constantly.

We have so much of it that I have tried, as an experiment once, cutting a section down to the ground. It came up even better.

I did look up in the "Southern Living Garden Problem Solver" because they are usually good about telling you what chemical to use to kill something. Their only listing is under "great plants to plant on a slope." Even THEY love the Mexican petunia.

Emily: Viva Mexican Petunia!

For the writer inquiring about Mexican petunias surviving Midwest winters, we live in St. Louis, MO, and have had a Mexican Petunia for over 4 years now.  It has lived through our winters (zone 5) and returned each spring with no problem.  It's gorgeous with no care whatsoever.

Emily: Non-native invasives!

Ruellia is a genus in the Acanthus Family. It comprises about 150 species native to tropical and temperate North and South America. Five species are native to Florida and three non-native exotic species have escaped cultivation and are listed as naturalized in the state. Of these three exotic species, clearly the one to watch is Mexican bluebell (Ruellia tweediana).

The wild species (Ruellia tweediana) can be invasive.

Ruellia brittoniana, 3 ft. tall purple, carries a warning about its invasiveness.

WARNING

Mexican petunia is listed as a Category I invasive species by the Florida Exotic Pest Plant Council. This means that it is "altering native plant communities by displacing native species, changing community structures or ecological functions, or hybridizing with natives". This warning applies to all parts of the state of Florida (and other areas with similar mild climates). Where hardy, the Mexican petunia excels at invading wetlands.

*Native Species:
Ruellia caroliniensis -
The plant generally ranges from 6-16" high.
Ruellia ciliosa - naturally occurring in Central and North Florida sandhills
Ruellia succulenta - found in South Florida rocky pinelands.

Generally not available are:
Ruellia noctiflora
- an extremely rare native of wet flatwoods and bogs in North Florida and the central Panhandle.
Ruellia pedunculata
, another rare native of wet flatwoods and bogs in a few North Florida counties.