Why is my plant giant, and all the blossoms keep dying?
No fruit is getting produced.
The latest theory (mea culpa: I've forgotten whose theory) is that Brandywine Sudduth is a Northern variety and much happier in the North than in the South. Of course, you haven't told us where you live, so I don't know if that's applicable. Nor did you tell us which Brandywine you're growing....
Brandywine Sudduth's DTM (days to maturity) is 85; the count begins when you plant the seedling. Fruit take about 50 days to reach maturity after the blossom is pollenized. So in other words, you shouldn't expect any fruit to begin growing (any blossom to be successfully pollinated) until about 35 days (5 weeks) after you set out the seedling. The plant knows when it's ready to support fruit. [Of course, we don't know which Brandywine you're growing. The DTM may be something else entirely.]
But wait! There are other factors! We don't know what the weather has been in your area. In general, tomato pollination fails if daytime temps reach 90-95 and nighttime lows are either below 55 or above 75.
And that's not all. You mention a giant plant and no fruit: that's a classic description. Perhaps you've been fertilizing your plant with way too much nitrogen?
Timeline of a Tomato Truss
I have the same issue with my Brandy Boy. All the others are fruiting like crazy. This isn't a surprise to me though, I knew it might be like this going in.
First time growing Brandy Boy this year and it was late to set. I finally gave it a kick with some bloom booster and I have quite a few fruit set now.
I have great luck with Brandywine, its one of my staples. I do live in the northeast though, which is supposedly good for Brandywine, at least according to anecdotal evidence here. But you gave no information at all. Where are you? When was it planted, is there enough sun/water/fertilizer? What has the weather been like? Even for me, with a history of it doing very well, it is weeks to months too soon to expect fruit. That leads me to believe you might live in a southern area, where a lot of people say it doesn't produce much. One theory has been that it does not do well in high temps and high humidity. So maybe post a photo and a little more info. You came to the right place.
Assuming we are talking about Sudduths Brandywine, I have some experience with getting good production out of these plants - I've been growing it for 5 years in a row now. Even though Brandywine is a late variety, I tend to get it along side a lot of my mid-season tomatoes. I generally harden my plants off fairly early and then plant them out as soon as I think they are safe from frosts and the nighttime temps are (generally) around 50 degrees.
I find that Brandywines seem to not only tolerate the cold, but they almost enjoy the cooler temps - In cooler, wet springs, I've had good fruit set on Brandywine when others were stagnating. One thing for certain is that they hate humidity and heat (80-90s and above). I already have a few brandywines with fruit set which were put out on May 1st, and I'll get a good couple more no doubt in the next few weeks, but it seems that every year, right around July / August, flowers will stop setting. Other plants continue to produce, some like NAR keep producing at the same rate without a hitch, but Brandywine will always trail off during the summer heat. As soon as temperatures go back down a little, it picks up where it left off... The shame of it is that a lot of these tomatoes won't ripen before the frost, but I do get a few more out of the deal.
If you want to give it a try next year, you could try what I do and plant them out early and be prepared to protect them - keeping in mind how they don't like the heat of summer.
As an aside, I read a post on pruning the other day and it got me thinking. In a lot of varieties, you can prune suckers here and there and probably not impact your yield too much; Brandywine doesn't seem to be one of those varieties. If you take into account that you might only get 1 or 2 set fruits per flower truss (maybe 3, but I don't tend to see that), pruning seems to severely hurt your yields, much more so than other varieties. The plants are a little finicky about setting blooms, so you're going to want as many blooms as you can get - best way to accomplish this is to let as much of the suckers grow as you can.
Well that makes sense, because I can never get my tomatoes out that early, so I depend on late summer/fall harvesting, but I get a good crop then. Heck, I waited until May 20th and here it is in early June and temps are back down into the 40s at night. It is one of the ones I make sure to protect as long as possible, though, knowing it will keep ripening and producing well into fall most years, so it is worth it.
Again, your problem COULD be where you are, if we knew where that was, or it might something different entirely.
I have an observation about brandywine. I have two gardens, a modest one in my yard and a second larger garden in an empty lot that is used somewhat as a community garden. I planted brandywine Suddeth's in both plots last year. The mineral soil is the same in both locations but the amendments are different. I use compost and manure in my home garden, and just manure in the community. The watering in my own back yard is through flood irrigation from a secondary water spigot. I flood irrigated it because I don't want tomato disease from splashing soil. The community garden is sprinkled with a single rotating head sprinkler that waters everyones crops at once. I am the one who does the water management in both plots so I manage soil moisture properly. One thing I noticed last year was that the brandywines in the community garden were very productive whereas the ones in my own back yard were less than half as productive. I am not sure whether the better production was caused by better pollination from the water drops falling on the flowers or whether the water on the plants cooled the flowers enough to allow pollination. I suspect the later because I do go out and shake my plants daily to help them pollinate and set fruit. I suppose it could be both. Brandywines have never been that productive for most people here in Utah because of the warm temperatures. So perhaps some of you in hotter climates might help your brandywines set fruit by sprinkling over the plants. Interestingly I did not get disease in my garden plot tomatoes from sprinkling because I mulch and because the water washes off the dirt that splashes up from the soil. Just some of my thoughts.
FWIW, I was in the same boat just a few days ago. Essentially, everything else I had planted started to set fruit 2-3 weeks ago, but the brandywine? Zilch.
Well I checked on monday and finally had not 1 or 2 but 3 tiny brandywines growing. So I guess Id give it another week or two before you really start to worry.