i just planted my vincas and most of the plants leaves are turning brown and leaves shrinking. what can I do?
Unfortunately, your photos did not come through. Most common causes for transplant shock will be disturbing the roots too much and overwatering. This will lead to infection.
I would treat with a fungicide and only water once the ground is completely dry down to about 2 or 3 inches.
Here are some articles that will help:
https://www.gardeningknowhow.com/ornamental/groundcover/periwinkle/growing-periwinkle.htm
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
Attached are (2) photo's of pest/disease problems I'm experiencing with my Vinca plants. Are you able to advise what the problem(s) is, and how to treat it? Thanks a lot !
This is going to be the same issue as your other plants. Verticillium is going to be widespread, and is very hard to control once it reaches this stage. Please refer to the article on your other question on tips to control this destructive disease.
In saw dust in the basement or garage?
If you mean the vinca minor trailing ground cover, it is hardy to zone 4 and just needs to be mulched well.
If you mean the bright annuals, they are not usually worth overwintering as they start to look bedraggled as they age. However, if you want to try, it is best to bring it inside to a sunny location and water lightly over the winter. Then move it back out when the threat of frost has passed. (Be sure to inspect for insects before bringing it in.)
https://www.gardeningknowhow.com/ornamental/flowers/annual-vinca/madagascar-periwinkle-care.htm
It has been growing in the same place for over 15 years and is very healthy looking, south facing but in the far North of Scotland (Shetland) where we have less sun and it is a colder and harsher environment. I've only seen two small flowers that cam out in October!
I would advise testing the soil soil for nutrient deficiencies or pH imbalances. Usually, this will have something to do with too much nitrogen and not enough phosphorus and potassium in the soil. It could be that the soil pH is off enough to prevent uptake of these nutrients, as well.
Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm
https://www.gardeningknowhow.com/ornamental/groundcover/periwinkle/growing-periwinkle.htm
I live in Phoenix, AZ. I planted white vinca with a red center in a flower bed which gets full sun. It is late January, and it is still blooming, although the blooms are smaller. If I cut them back in March, and apply Miracle Grow, will the continue to bloom this summer? I have had luck with vinca in pots by doing this.
Yes, vinca is perennial in your area so it should continue to bloom. It will benefit from shearing and fertilizer as you suggest. Here is more:
https://www.gardeningknowhow.com/ornamental/flowers/annual-vinca/madagascar-periwinkle-care.htm
I planted some vinca and a couple of days later I noticed white spots on some of the leaves. Could they possibly be fungus or some disease that could spread to my other plants? Do I need to treat his, uproot the plants or ignore it?
It may be sunburn. Here is more:
https://www.gardeningknowhow.com/plant-problems/environmental/leaf-scald-in-plants.htm