DivinylsFan I know it's easy to get to visa level 3, which is why I haven't done all the adventures. I don't generally grind enough to accomplish it in one trip though, and I space out the trips, so it takes a while for my sims to actually get there.
The grapes (I meant cranerlet nuala and gralladina fran, only available at visal level 3) do grow in the basement of the Landgraab estate, and probably at the abandoned house too, although I haven't checked there in a while. But there are only a few plants each, and my sims want to make nectar while they're waiting for their crops to mature, so collecting a large quantity at once is much more convenient. Not to mention, my sims sleep overnight on the island and get another pass through Tuatha's Garden the next day without having to travel over there again.
My understanding is the island is only accessible by swimming (which takes a very long time) or Zeneport (which means time spent building the Martial Arts skill and meditating), so it's not any better from an efficiency perspective. And this way, they get treasure along with enough grapes to last until one of them can plant and harvest the rare grapes at home.
To get to the island, just go into map view, click to go there and the sims will automatically go there via taxi-boat if they don't have their own boat from home in their inventory. Swimming is just a romantic thing for taking pictures in stories, and doesn't take all that long and is definitely not necessary. The dark blue grapes and the red grapes are available on that island, around the blocks of ruins, as well as a few butterflies and bugs and a couple of fishing spots, and a tent or two will fit on there. There's also a couple of excavation spots. The grapes will definitely be ready for harvest by the last day of the shortest holiday. I always make my sims go there for them by rule of thumb. Whereas the pink one's they can get over at the tiered front garden of the vacant holiday house at the end of the foreshore. And of course the green, yellow and white ones, but they can be got at the winery vineyard too. To grow them at home you only need one of each, which you have to keep replanting until you get the perfect quality anyway, so if you plant more than one its too much work. Unless your sim has top gardening skills, a quick-gro station, fertiliser, and science radiation experiment thingy, but they still need replanting once or twice. Even if they don't need replanting, you still only need one because the plant produces more.
That's been my experience anyway. I've probably got some photos somewhere.
DivinylsFan I don't have Island Paradise active right now (installed, but I hid its registry entry so it doesn't load). Plus, it feels a bit cheaty to just boat right up when the original intent was to make it difficult to access the island.
The Meloire (pink) grapes are available with a level 2 visa; the Avornalino (green) ones are available at level 1, I believe, plus there's a row of them at the Nectary. Cherimola Blan (white) and Renoit (yellow) can be purchased from the food vendor.
The issue, for my gameplay at least, is that Cranerlet Nuala (red) and Gralladina Fran (blue) are only available with a level 3 visa, or in one of the locations I listed, and they're rare and so take a level 7 gardener to plant them, AND they make excellent nectar. So my sims are ready to make wine that includes these grapes before they can grow them, or at least before they have a garden full of these plants. (I don't like to plant more than one until I get to Perfect or at least Outstanding, as it seems like a bit of a waste.) Collecting ~20 of each means more interesting nectar recipes, and more money coming in, while my sims are experimenting as they learn the skill.
