Jasmine vine grew last year. The vine is growing back at the bottom. Do I need to cut the vine down from last year's vines or will the vine come back to life?
Let's start with some basic jasmine growing tips: https://www.gardeningknowhow.com/ornamental/flowers/jasmine/growing-jasmine-plants.htm
I take it that your jasmine was cold damaged last winter, and is now growing back from the roots. If the higher vines have died, they won't come back to life; if there's life still in them, they should have sent out shoots by now, but you can test them by breaking or cutting them. If they're all brown and crispy, they're dead. If they're pliable and have green tissues at all, they're alive. Go ahead and cut off the dead vines.
I have 5-6 very large (size of an avacado) seeds on my vine. Can I plant them?
I suspect what you're looking at are seed pods. This article has information on the many types of plant known as jasmine, and how to plant the seeds: https://www.doityourself.com/stry/growing-and-planting-jasmine-from-seeds#b
I have a vine of jasmine left and it's half alive and looks like a mess but I want to bring it back to life. Should I prune it back a lot and see what happens or just give up and plant a new one?
You can plant another one, but it might be helpful to learn what happened to the first one, so the same thing doesn't happen again. You can also prune severely, and see what happens. I'm going to give you a couple of articles on growing and pruning jasmine, but without knowing more about what your "mess" looks like, or which kind of jasmine (there are dozens of different plants called jasmine) you have, I'm afraid I can't be more helpful.
I bought a 10-inch high plant from a nursery, planted it in soil about three months ago and in three months it has grown to 24 inches. The leaves are green and the plant is good. The only thing is no flowers and no beautiful fragrance. I have watered it normally also with Neptune seaweed fertilizer. Could you please help?
I don't know exactly what plant you are referring to; blooming night jasmine is Cestrum nocturnum. then there are several lilies that bloom at night, any of which can be known by the common name of night lily or lily of the night. Without being able to look up any specific information on the plant, I can give you an article which lists common reasons for plants failing to flower: https://www.gardeningknowhow.com/plant-problems/environmental/plant-not-blooming.htm
I have a summer flowering jasmine shrub about 1.5m high x 2m across in a corner of me garden and I want to move it to a different place. When is the best time to do this?
Some bushes like to be transplanted when they're dormant (early or late winter,) but most plants prefer to be moved in early spring, before they've started to grow, to early summer, when they're full of energy. Also, there are hundreds of varieties of jasmine, and without knowing the particularities of yours, or of your weather, it's hard for me to say for sure that you can move the plant now. Here's an article about things you want to be careful of in transplanting: https://www.gardeningknowhow.com/plant-problems/environmental/learn-how-to-avoid-and-repair-transplant-shock-in-plants.htm
You might use the nearest botanical garden to put you in touch with a Master Gardener who could give you more specific advice>
I had the potted jasmine plant outside and brought it in before the temperatures dropped. I have it in front of a sunny window, but the leaves started falling off. I don't see any mites on the plant.
If you don't see any bugs, chances are the reduction of light between outdoors and indoors, even though the plant is in a sunny window, has been enough to cause the leaf drop. Plants do better when they are slowly accustomed to the lower light. This article will tell you more: https://www.gardeningknowhow.com/houseplants/hpgen/acclimate-plants-indoors-winter.htm
We planted a Boston Ivy and night blooming Jasmine together thinking it would be beautiful. However, 5 years later the jasmine has completely taken over and is strangling the beautiful ivy. How can we prune the jasmine way back, without killing it?
Pruning jasmine is easy - just get a pair of pruners, and whack away. Of course there's more to it than that. The best time to prune is just after flowering, but since you feel that yours is overwhelming you, you probably won't mind losing flowers for a year, if you cut at the wrong time. So go ahead and prune as soon as you want, and feel free to cut back a lot. This article will give you some encouragement: https://www.gardeningknowhow.com/ornamental/flowers/jasmine/trimming-jasmine-plants.htm