Rowans are often called berries when in fact the fruit is a pome, the same family as apples.
Incidentally, close up they really look like little apples. For poetic satisfaction, as well as practical reasons, it is a good idea to make rowan jelly with some apples in the mix. Apples give it a good flavour and help to set it as rowans do not have a high pectin content. You can make rowan jelly exclusively with rowans but it is more difficult to get it to set. The quantities you make depend on how many rowans you pick. The ingredients below follow a simple formula using a one to one ratio for all the ingredients.
For example, for every 1 kg of rowans you pick use 1kg of apples and you boil them in 1 litre of water. For every litre of juice you get from this you use 1 kg of sugar.
When you have picked the rowans remove the leaves and all the stalks. This can take a bit of time but it is an easy job. Wash them in a large bowl, with several changes of water until it comes out clean.
Put them in a large pot with the apples and the water. Bring to a boil and simmer for 20 - 30 minutes. When the rowans are very soft take it off the heat and mash them with a potato masher.
Strain this mixture through a fine sieve. Traditionally it would be strained through muslin or cloth but this is not necessary as you still get a clear jelly straining through a sieve. Leave this to drip through. I usually leave this overnight to get every last drop.
In a large pot dissolve the sugar in the strained juice over a low heat. Now turn the heat up as high as it will go and boil until it reaches 104˚C. It should take 10-15 minutes of vigorous boiling.
The other way to tell that the jelly will set is to spoon a small amount on to a very cold plate. After 1 minute the jelly should wrinkle up when you push it with your finger. It is a good idea to put 3 - 4 plates in the freezer so you can retest it easily if need be.
Remove any scum from the top while boiling. You will be able to remove any remaining scum when it comes off the heat as it always rises to the surface. This should give you a crystal clear jelly.
Pour into cleaned and sterilised jars.