Can this plant be brought indoors for the winter? Is it to be treated the same as Mandevilla?
Yes, these are pretty much the same thing so treat them as such. Bring the plant indoors prior to your frist frost and allow it to go dormant. It will only need watering once a month during dormancy to keep the plant from drying out completely. Once spring returns and new growth begins, you can move it back outdoors (after threat of frost) and care as usual.
Will dipladenia survive winter outside? Thank you.
Dipladenia is a tropical plant, hardy only to zone9 - that is, it can take a few days of freezing to slightly below freezing, but in general it should not be kept below 40 F (4.5 C). This article has more information on dipladenia: https://www.gardeningknowhow.com/ornamental/vines/mandevilla/growing-a-dipladenia.htm
How much sun does the Dipladenia need? Can I plant them in flower beds? Or do they do better in pots?
Dipladenia is perennial, rated for USDA plant hardiness zones 9-11. Dipladenia prefer bright but indirect sun. Given that your planting zone is 6a you will probably want to pursue dipladenia as a potted plant. You can situate your potted plant outdoors until temperatures dip below 60 degrees.
For more information on dipladenia, please visit the following link:
I live in Malta with a hot long summer conditions. I wish to plant the dipladenia. Is it suitable for direct sun of 8 hours a day?
Here is a link to growing and caring for Dipladenia.
I bought it at a nursery in May and planted it in a container. It wasn't blooming then and never has. It has grown quite a bit but no blooms. Any clues?
Make sure your plant is receiving plenty of light. Temperatures should be warm enough.
Here are two links with all the care instructions including fertilizing information.
How high does a dipladenia mandevilla grow?
3 to 10 feet.
If it's a container plant it will not reach as tall of a height as if it was planted in the ground.
Just bought, it's about four feet tall in excellent conditions with plenty of flowers and new buds. Can I keep it in my conservatory? It's got plenty of daylight and the sun comes round in the afternoon. How long should it flower?
This should be an excellent spot to grow your new plant.
Here is a like with growing information.