My 4 dipladenia plants are beautiful, and have been all summer. Now there are long vines coming out of two of them, but not the other two. Have never grown dipladenia before, so I would like to know what these vines are. Thanks
Are you sure you don't have a Mandevilla plant rather than a Dipladenia? Both are similar in almost every way except Mandevillas are an all-out vine and Dipladenia tend to be bushier and their extensions hang instead of climb.
This article may help you determine with some degree of certainty which plant you have:
It is bushy & looks real healthy but hasn't bloomed this summer. I have it planted in a big well-drained pot in bright sun and water frequently. This is its 2nd summer. I winter it over in our garage. I fed it liquid fertilizer about once a month. It was loaded with blooms last summer. Could it be root bound in the 14" pot? We live in Iowa, where my summer flowers usually thrive.
Dipladenia need some specific growing conditions to bloom.
These links will help you.
Can I keep them in my basement which gets limited light? Can I cut them back when wintering? I live in coastal Maine. If wintering is successful, when should they be brought out and fertilized?
This article has plenty of information on winter care for Dipladenia (a type of Mandevilla):
According to the article, you can either cut the plant back and then store in a low-light basement which is at about 55-60 degrees, or you can keep the plant as a houseplant through the winter.
In either case, you can fertilize and put the plant outside as soon as the danger of frost is past and the temperature is above 60 degrees most days. It looks like this would happen around mid-late May in coastal Maine.
Long spiney growths growing out from top of plant.
I suspect your plant is trying to spread so it can expand beyond its pot. Dipladenias will usually grow in a vining form unless confined to a pot, but even so, they will put out side stems that I believe are basically runners. You can cut them off at the base to prevent further development.
We brought the plant indoors for the winter. Now the leaves are turning yellow and falling off. Is this normal? I read a few articles but couldn't find an answer. Thank you.
It is normal and common for plants to lose some leaves when they are brough indoors. The cause is usually the lower light levels indoors, which light-loving plants like Dipladenia have trouble with. If you can provide more light (natural or artificial) it will help. See this article for other options:
I have a plant tagged as Dipladenia.It does look like it from your photo but it has a vine that started growing just recently and it is now about 3 feet TALL(that is growing up and not hanging down)Is it Dipladenia?
Both plants will vine and have similar growth patterns.
Dipladenia and Mandevilla are sometimes miss tagged.
Here is an article to help you make the identification.
I have a Dipladenia plant, which leaves keeping turning yellow. I pit dishwashing soap to clean up soil, and hopefully to quit losing yell0w, falling off leaves? I keep in bright light in my three seasons room during the winter. Thanks in advance for any help you may find.
Yellowing leaves could be watering issues; too much or too little, or temperature issues.
Water the plant when the top inch or so dries.
Make sure the soil is well draining.