The nodes at Nophica's Wells are very compact. When you first arrive, complete a loop around the Westernmost canyon area and you'll find two harvesting spots and a tree. There's always a tree there. This makes it very simple to find three locations without needing Arbor Call IV. You could come here as low as 20 and still turn out reasonably good experience, as harvesting spots should still yield around 200 for a successful gather.

At 35ish, head to Iron Lake as, like Nophica's Wells, the nodes there are very compact, except even more so. They are simple to find without Arbor Call V and you have a high chance of multiple trees spawning within sight of each other, seriously speeding up your gathering.

On the Western side of the main Iron Lake area there is two harvesting spots within sight of each other. Combined with one tree, these two can power level you to a high level from as low as 30+, assuming you are using sufficient gathering and output gear. I couldn't tell you exactly how much of each stat you will need as the formula has been changed since I levelled Botanist.

However, due to the compact nodes and the low amount of aggresive monsters at Iron Lake, it makes it a very fast camp for those who 'technically' shouldn't be there yet.