Looks like to me way too much water. Vinca generally wants to be drowned and then completely dried out. Try not watering until they dry out.

they may be baking with all that see-ment around.. as jethro would say ...

i havent tried to grow these in decades.. something makes me think they are a shade plant.. and to me.. shade means cool ... not the retained heat of cement ...

i had a brick patio at the old house.. you could go out at 2am ... and it would still be hot ... i had no mildew on the roses around it .. but i also could not grow plants the need to cool off at night and recover ...

ken

These vinca (planted with the taller Angelonia) get nothing but neglect, but they grow. These are all reseeded--the original plants were probably planted about three or four years ago. They are getting paler (the original plants were a darker pink) Interestingly when I try to dig up some of the seedlings and move them to a new spot, some make it, some don't. Typically it seems that smaller seedlings--maybe 3-inch plant with a bud, is more likely to survive. It if has a bloom already and I try to move it, it usually goes down fast. These are planted where they get full sun most of the day. I pretty much never water them or the angelonia, which thrives in the heat..

I get Phytophthora blight quite a bit. Love vincas; hate that common disease. See link.

Here is a link that might be useful: Blight

I find they like to be dry and hot

Did you fill your bed with potting soil? Your picture looks that way. If so, that is a contributor to the problem. Take your spade and mix it into the native soil.

Definitely, your biggest problem is over watering. Vinca are virtually indestructible, but they won't survive too wet conditions.

And just FYI, they are full sun lovers, though they will do okay with half day sun.

bugbite, thank you for that link! Answered my problem with vinca this year.

You're welcome patann. When you know what the disease looks like, you know it is the disease, not you. Sometimes they mutate and an occasional resistant one continues to grow. Occasionally I find a volunteer who survives when the others get hit.
I studied Cora's patent to find the chemical in the plant that provides the resistance. Unfortunately even Cora is more resistance to the Texas strain and not the Florida strain according to the seed developer, in conversations I had with them. That's a bummer cause I love the plant and have tried many of the varieties just to see if I could get lucky.
All the vincas in this picture got the disease within 4-6 weeks of the picture and died. They were volunteers.
Good Luck.

This post was edited by bugbite on Fri, Jul 5, 13 at 17:50