There are around 30 bushes along this itinerary. And this is a map of all 3 locations covered in this guide:
Location #1: Greentop Nursery to Old Gullet Sinkhole
This is the best area in the game to get a lot of hubflowers really fast. Travel between these 3 spots and keep an eye out for hubflower bushes. Behind trees, near buildings, they are everywhere. You should be able to obtain around 30 flowers, and they will respawn with time. This is the location of this area on the map:
Location #2: Parsons State Insane Asylum
There’s a total of around 15 plants in this location, including the ones around the property. Unfortunately, the plants in the building’s proximity don’t respawn, but it’s still a great spot to get around 15 hubflowers without having to search a lot. Most plants are in front of the building’s main entrance, some in the back, and a few outside, near the main gate.
Location #3: Wildwood Cemetery
If you stick to the red pathways, you will find most plants, very easily. There’s one off the red path, on the top of the cemetery. Near it, on a road with a red truck, you will find a few more. There’s one outside the fence, near 3 cars. A few more can be found on the road leading to the water body.
Location #4: Recon Bunker Theta
If you follow the path traced on the following image, you will be able to find over 10 hubflowers: Most flowers are found by the side of the roads leading to the bunker, both paved and unpaved roads. There are also many other flowers near the 2 water bodies circled in red. While this area is great for hubflower farming, there are many enemies to be found here. If you’re not confident in your combat skills, leave this area for later stages of the game.