I'm pretty sure ferns have external sensory data. For one, they know which direction the sunlight is strongest. For two, they know when they're being attacked by bugs and can release chemicals that warn the other ferns to start producing defenses. Plants are much more aware than we generally give them credit for.
Plants feel a lot. I've worked with a European start up for a short while, they're making plant well being sensors for farmers. These sensors detect internal signals plants produce. Plants are capable of discerning animal touch from the wind, temperature changes, damage caused by insects, etc. They can feel everything, but can't react much.
Things get even more complex in the forests, where trees exchange resources with each other through underground fungi networks. Trees in the forest not only react to the environment, but also talk to each other and help each other. That's why replanting forests is very hard and takes a lot of time - creating this underground network is essential, but it's a very slow process.
I was blown away when I learned about their underground communication network. The earth is so much more full of awareness than I was taught as a kid, and we're just starting to scratch the surface of the sentence of all these life forms on our planet.
In addition, plants accurately compute their circumstances, use sophisticated cost–benefit analysis, and take tightly controlled actions to mitigate and control diverse environmental stressors.
Whoa, so, they're better at planning than I am. ;p