You can have at most 15 missions at the same time, and you can surrender any missions but the principle types. Goldenrod Nectar (a dark yellow colour, much like the colour of the jasmine nectar) can be produced by planting a goldenrod flower (goldenrod seeds are unlocked at lvl. 34) https://directory-fast.com/listings9350/key-traveling-suggestions-that-can-easily-make-a-genuine-difference