If this is a new house, just built, then there is a good possibility that the painters or other workers used the area to dump turpentine or other chemicals, wash brushes, and etc. I had an area like that and it took a long time for anything to start growing and thrive. If that is a possibility you could dig out the area and replace with compost and/or a good planting mix. There are probably some soil ammendments that would help too. I've heard zeolite is good for that. Luckily it's only 2X2. If it is not a new house, you may have a soil or water born disease in that area. I know vinca (periwinkle) are very susceptible, and once you have it, your only option is to plant things that are not affected by it. I've not had experience with the disease, so hopefully others on the forum can give you more information, if that is possibly your problem. Good luck.

This house is about seven years old...could chemicals still be a problem?

I didn't know vinca was susceptible to disease. Rats. I have a whole flat's worth in there.

Put in something you hate! It will trive of course.(J/K)
Wet/dry plants include canna,tx star hibiscus,Ruellia and elephant ears. They all tolerate shade and sun too.PJ

You cannot kill canna or elephant ears....if you don't want to water much, try lantana.

You might consider getting a soil sample analyzed from that area.

Kristi

I tend to agree something got dumped there. Might not have been during initial construction. Maybe it was just their dog's favorite place to go. Who knows? Since its a relatively small area, I'd dig up about a foot of it and replace it with good garden soil.

At least that way you will know if things keep dying there its more likely location issues (sun, shade, water, competing roots, etc).

Are there gas lines running thru the area? Just a thought.

I have found that tacoma stans can take drought or they can be next to a drain spout and endure massive amounts of standing water when it rains. I don't know if you'd want a 4X4/5X5 plant in that location. In zone 9, it would come back every year. (Is it tecoma? I never can remember. I mean esperanza or yellow bells.)
Don

I took a couple of the diseased vinca to a nursery yesterday for diagnosis, and was told they're just rotting. (?) Obviously, the employee could only examine the plants I had then, but I seriously don't thing rot was the (only?) issue last year with the other varieties.

Maybe I will get the soil tested.

Thank you, everyone...and if there are any more suggestions, bring them on. =)

Tiffany

It's possible that the vinca are just planted a little too early. Used to you never found them in the nurseries until May/June as replacements for cool season annuals. Now they have them out in March. Vincas really like the heat, so it could be the cool temps of early spring are not allowing the soil to dry enough and that is contributing the the rotting. Maybe just try to baby them till the temps go up, or wait awhile before you try to replant them.

Fusarium wilt has become all too common with periwinkles (vincas) planted in the soil. The disease takes out 90% of plantings in many areas. It is soil-borne and remains in the soil for years. As the previous poster suggested, March is far too early to plant periwinkle in Texas anyway unless you are in the lower Rio Grande Valley. If you like periwinkle, they are best grown in containers placed so that water from a contaminated bed won't splash up on the foliage. It's usually warm enough by June 1 to plant them. They are very unhappy with cool nights (or days). The upside is that it can't get too hot for them unless they are allowed to get so dry they die. Often they will show some wilting (from lack of water, not from the fusarium wilt) in the heat of the afternoon but will snap back later in the evening.
Don

It's too early to plant vinca (I'm assuming perriwinkles)

They are a succulent and really hate to have wet feet. If you see this, it's likely that you have a fungus that gets them. This funugs may also attack zinnias.

Think about all the rain you've had recently.

I've even experimented with perriwinkles. I put some out in May, they did great, I put out several flats, it rained the first week of June and slowly they all died. Grrrr!

Keep trying and do get your soil analyzed, but mostly, be patient and wait until after the spring rains before planting vinca. I don't know why nursery suppliers get them in so early, I guess it's because we love them so.
cynthia

Dang it!! Now that you all are saying this, I vaguely recall reading this about vinca and hearing not to plant until June. I did not remember that last month when i was doing a little impulse buying and planting! i've got white vincas (only 3 or 4 small plants) planted out front, and now I will know to expect to loose them soon (esp. with this cold weather predicted this weekend!!). Phooey. At least I didn't spend too much on them. At the moment they look great, but we'll see.

June may be a little late in your zone. Last year even here June was a scorcher. But early May should be about right, and give your new plants a chance to get going before the heat sets in.

I have a dead zone too & was digging in it yesterday & found huge chunks of concrete that was thrown in there when they poured the sidewalk 23 years ago. Maybe that's why nothing would grow there. I always thought it was too much heat & not enough moisture being as it was the triangle where the driveway & sidewalk met. I've got iris there now after seeing a neighbor with thriving iris in the same type spot.

If the soil analysis doesn't show anything, maybe you could look around your neighborhood & see if anyone has a similar area. Do weeds grow in that spot?

Speculation could go on forever about what may lie under the soil or what contaminants may somehow have gotten in the soil. Why don't you plant whatever you want, and whatever can take the moisture and sun conditions in this spot, in POTS and bury them just below the surface of the soil. Then if the plants fail to thrive, you will be able to rule out some possibilities that have been offered.
Don

Male goat urine is what we use in my home land to make bad dirt clean to plant things. It does many things and is good for roses keeps them growing and making flowers but it will get rid of pisons in dirt too.

Don, I tried what you suggested as to burying pots. The amaranthus I put in at the far side of this area is making it. The stuff I put in the center of the problem area is dying.

I guess I will plan to go ahead and replace all the dirt.

Thanks for the help! =)