While Cal is exploring the Jedi galaxy: Fallen Order, he can find unique plants and acquire their seeds with the help of BD-1. You will come across many of them on your travels, but some are off the beaten track. Here is where you get all the seeds.
Bogano
Kalpi
You can find the Kalpi Seed at the very beginning of your journey to Bogano, in the Underground Refuge section. When you get to this area, jump to the ground and kill the lurking bog rats. Make sure you are at the bottom of the area and go to the small enclave on the right side. BD-1 should join it and scan the first seed file.
Featherfern
On the first planet, Bogano, you will find the Oil Feather in the Fractured Plain. It will be next to the Bogdo sinkholes. All you have to do is jump over it from the chasms, and you should be good to go. BD-1 will execute the purple plant and scan it for you. You will however need the double jump to get it.
Zeffo
Gillypod
To find Gillypod's Seed, you must go to the Windswept Ruins. You can get it before entering Eliram's Tomb. When you are at the ruins, you will find him in the highest column, in the middle of the large area just before entering the tomb. You will know you found it near the little red flower in the middle of the pillar, in a small mound of dirt.
Fluzz Royal
To find the Royal Fluzz you need to go to the Meteorological Monument area, where there are two ranged stormtroopers and two melee, take them out and then run over a wall to the nearest meditation point. To the left of the meditation point is a heavy gunner stormtrooper that you need to take out. After that, go forward and you'll find another heavy shooter waiting for you, standing in front of three pipes that you have to go through to defeat them. Walk forward a bit and to the left you should see a chest that you need BD-1 to slice on. The seed is right next to it.
Dreamwort
You'll find this seed near the Venator crash site in Zeffo. It's going to be to the right of La Jotaz wandering around the little circle. You might get into a fight with part of the Scazz, which prevents the BD-1 from scanning it. Kill the Scazz first, and then you can grab the plant.
Kashyyyk
Bonshyyyr
When you are on Kashyyyk, in the Imperial Refinery, you can find the Bonshyyyr seed. You will find the seeds in the area where the Imperial troops fight the giant spiders. They'll fight, and when they're done, you can find the seeds right next to the open crate in the middle of the area.
Grass milk
When you visit Kashyyyk for the second time, you can find the Milk Grass seed at the Gloomroot Hollow location. It will be on the left after seeing the stormtrooper being eaten by Venus' fly trap plants. Go left by jumping over the Venus fly trap and go to the raised area. You might be chased by the reddish plants, but you can quickly follow them. The Brass plant is the large, multi-leafed plant.
Mushbloom
On Kashyyyk, you will get closer to the Original Tree, the sacred tree of the Wookiees. You can find the Mushbloom seed in the original Tree area of the game and it will be surrounded by several dangerous creatures. You're going to fight three of the giant spiders, and it's under a lung plant.
Dathomir
Bleeding from the intestines
You will find the first seed of Dathomir in the Swamp of Sacrifice. It goes right next to the rope as you jump. There is a save point nearby, overlooking the large area with lots of killer spiders. Take care of the spiders and then look for the red plant. BD-1 should scan it.
Mushling
At the bottom of Dathomir, you will explore the Marsh of Sacrifice. You are going to find this seed closer to the back after battling a horde of undead Nightsister witches that appear from the eggs of a tree. Kill them, then go to the left of the tree. BD-1 should be run and start scanning the installation.
When you get all of the seeds listed above, you won't get success immediately. You have to wait a bit for them to grow up. Take on missions or manipulate other collectibles and come back to check their progress.