One of the first signs that spring has sprung is when small, neatly wrapped parcels of leaves start to appear on the trees. These buds indicate not only the start of spring but that the sap is rising, and the sap from the birch can be tapped and drunk. The ambrosial birch sap need not be just a taste of early spring as it can be preserved as a wine. Any birch tree can be tapped, but ensure you tap an older tree of at least 25–30cm in diameter: any smaller and you risk damaging the tree before it has had a chance to grow. Drill a hole into the tree at a 30-degree angle facing downwards. The hole should just penetrate the bark and should be as thick as the piece of tube you will need to insert into the tree. Push the tubing right into the tree and put the other end in a bottle or demijohn. Leave for a day or two, returning twice daily to check on progress. If the sap that comes out smells and looks a bit like dog pee then the tree has been infected with a fungus and the sap should be discarded.
It can be difficult to tap a birch tree if you live in a town or city. My friend and fellow forager Fergus Drennan suggests that you climb the tree and tape or tie the demijohn to a higher branch before tapping up there. The sap rises right up the tree so you should still get a good amount.
When you have finished tapping the tree, make sure you plug up the hole. There are several ways to do this, including shoving a piece of cork into the hole and covering it with wax so you can come back on alternate years, pick the wax off, pull out the cork and tap again. Personally, when I plug a birch I find a small twig or branch underneath the tree, cut that to shape with a penknife then hammer it home with a stone. If you don’t plug a tree you leave it open to infection, which could kill it.
Birch sap does not keep very well and should be put into use as soon as possible. If refrigerated it will last for only a few days, but it can be frozen until needed.
Birch sap wine is certainly a delicacy of the woods, so much so that it is available commercially in many countries. By altering the amount of sugar used in the fermentation process you can determine how sweet or dry your wine turns out to be. This recipe will make a slightly dry wine.
BIRCH SAP WINE
4.5 litres birch sap
250ml white grape concentrate
2 tsp citric acid
half tsp tannin
Hock wine yeast
Bring the sap, concentrate and sugar to the boil, remove from the heat and add the citric acid, then stir until the sugar has fully dissolved. Allow to cool to room temperature then stir in the tannin and sprinkle the yeast on. Cover loosely and leave for ten days.
Siphon into a demijohn and rack after about four weeks. Allow to ferment out before bottling and age for at least three months.
First published on the Observer Organic Allotment blog