It is said that the sap of birches has many virtues. My (vain) grandfather smeared it on his head to prevent hairloss and it is generally believed that it is an excellent treatment for poor health, as a revitalising tonic etc. It is a watery substance, slightly sweet with a silky taste. It is also used to make excellent wines. Birch sap is harvested at the end of winter by the end of February, early March when the first buds start to swell. The harvesting period is short: about two weeks, so if you want to do this you will need to keep a close watch on nature. The recipe I used is taken from an old book by the excellent J.C.C. Berry. Wine making is not difficult; just make sure you work very clean with sterilised equiment. See my instructable on making rose hip wine on this subject.

Step 1: What Will You Need?

You will need the following stuff. Most can be found in your shed and local supermarket, the rest is bought from a specilised wine makers shop. Quantities are for 5 litres, scale up or down as needed.

A hydrometer
Waterlock(s)
measuring glass
a cork or plug with a hole in it
a hard-plastic or glass pipe, 5-10 cm that snugly fits in the hole in the above cork
A tube, 100-150 cm. The diameter should fit the above pipe
A drill with the same diameter as the small end of the cork
A drilling machine (or hand drill) you can take out in the field
Yeast (we will make a white wine, so can use e.g. Elzas style yeast)
Yeast nutrient
1500 g. sugar, 500 g. raisins, 2 lemons, 2 oranges (use organic raisins, lemons & oranges, you do not want chemicals in your wine)
Something to sterilise your equipment, I use sulphite.
A vessel, large bottle or Demijohn for collecting & fermenting. Actually: it helps to have two/three since you will need to rack off the wine a few times while clearing. You can also use food-grade plastic buckets for this; you can probably get them at a local snack bar or restaurant, they use them for sauses. Make sure you get the lid as well. Drill a small hole in the lid to connect the waterlock; make sure the waterlock is not leaking.
A large (soup) pan
5 litres of Birch Sap.

Step 2: Collecting Your Sap

So you will need to collect 5 litres of birch sap! As said before: the time to do this is when the first buds start to swell, late February, early March. Look for a period without frost. Frozen liquid will expand and can break your bottle. Look out for large and healthy trees with a diameter of at least 25 cm. Remember that you rob the tree of vital nutrients, so keep it reasonable. Do not harvest more than 5 litres from one tree and treat the tree with respect. There are two ways of collecting. The first is by cutting off the end of a branch and shove a bottle over it. Tie the bottle to the branch and you will see the sap dripping down almost immediately. This is nice for small amounts, and we need at least 5 litres.

This is how you go about: prepare the tube by connecting the pipe and cork. The cork will go into the tree. Clean a large bottle and connect the other side of the tube to the bottle. On the photo you can see I use a rubber cap used to put a waterlock on a bottle; this works perfectly.

Drill a shallow hole in the tree, point your drill slightly upwards; you want the sap to flow down. The height should be higher than the bottle you use; sap flows down, remember? There is no need to drill deeper than 2-3 cm since the sap flows just below the bark. Put the cork in the hole you drilled, make sure it fits tightly.

Make sure everything is steady; make sure the bottle cannot be toppled over by cattle or wild animals.

Leave and come back the following days to see the progress. After a few days (the sap will flow surprisingly fast!) the bottle will be full. Take the cork out of the hole and plug it firmly with a piece of wood; you may need a hammer for this. This is important since the tree can literally bleed to death if you don't do this. Actually: a few weeks later you will notice that the tree you tapped from will grow leaves 2-3 weeks later than trees you did not tap from. Say thank-you to the tree and take the birch sap home and put it in a dark cool place.

Step 3: Make Wine

Mix the yeast with a cup of luke warm water and let it rehydrate for 2-3 hours on a warm spot
Chop the raisins finely
Peel the lemons and oranges, remove all the white stuff from the fruit and squize out al the sap.
Heat the birch sap to at least 90 C (or cook, I don' t cook it since I want as mucb flavour as possible) add the lemon/orange peel and sugar, make sure the sugar dissolves. Do this for 20-25 minutes. Take a sample and weigh it with the hydrometer. Ideally you should read around 1080. When below: add some sugar. When above: prepare for a sweet wine or add water/sap. You can do this in batches if your pan isn't big enough; make sure you cover the vessel/bottle thoroughly every time to prevent polution by wild yeasts and other vermins.
Put the chopped raisins in the vessel/bottle you will use for the fermentation, pour the liquid over it. Make sure the bottle is filled no more than 50%. The fermentation will produce froth that can come out through the waterlock creating a mess. You do not want that. You may want to use multiple vessels for this stage, when the fermentation is out of its "wild" phase you can mix them together.
When the temperature of the liquid matches the temperature of the rehydrated yeast, pour the yeast in the liquid, add the yeast nutrient.
Close the vessel(s), add waterlock and let the fermentation begin!
When the fermentation slows down you rack the wine off leaving all the rubbish in the first vessel. When there are no more bubbles in the waterlock you weigh the wine again. For a dry wine your hydrometer should read around 990. Higher means more sugar is left, resulting in a sweeter wine. Do this every two months untill the wine is perfectly clear. Make sure you leave no more than 2-3 cm under the rim of the bottle to avoid oxydation. Use any good white wine available to top off when necessary.
Bottle the wine, leave to mature for a few months and enjoy with your friends!