Originally posted by Arachnovia:

There can be various reasons for this.

1) you planted the bulbs too close to a wall or other structure.
2) you planted the plants too close to each other. as a result, they wither and die.
3) you planted the bulbs in the wrong biome.
and last but not least 4) you accidentally destroyed the plants after they were planted. This can happen if the hammer or the plow breaks while you are using them, then your character will kick and this can destroy plants.

I came here to post 2 and 3. Also don't kick your plants that's mean.