the easiest way to preserve plant essence is to make a jam. There are many possible recipes but it is always interesting to experiment a bit. This is one of my favorite.
Strawberry rose petal jam
Ingredients
500g fresh strawberries
a handful of fresh rose petals (any rose petals are good, but make sure they are not sprayed or growing too close to the road)
400g sugar
1 bag agar agar
1 glass of water
Method
place strawberries, rose petals and water in a big pot
let them simmer on low temperature till strawberries are pale pink and soft
sieve it well
pour the juice back into the pot, add sugar and let it cook for a while till it becomes slightly thick