How to make birch sap wine

Nothing in the forager's calendar is more seasonal than birch sap. Blackberries, wild garlic and most other wild foods are around for months; with birch sap you have two weeks, three at the most. In Dorset, where I live, it is approximately the middle two weeks of March, but it can be slightly earlier or later, depending on the weather. It may seem a little early to talk about it now but you do need to be prepared for birch tapping - mentally, physically and administratively - so I am giving you a head start.

I am going to come clean. I do not see the point of birch sap wine. With most alcoholic drinks the ingredients are there to provide the flavour or the sugar and sometimes both. Birch sap wine contains very little of either so it cannot do these things – it just supplies the water. But I know that a lot of people swear by the stuff and will disagree with my dismissal of what they consider to be a first class wine. If you like birch sap wine let me know and tell me why I am wrong. No, really.

Having said all that, I do love collecting birch sap so, apart from the odd batch of wine to remind myself how right I am, I make birch sap syrup to pour on my pancakes. I boil the fresh sap down until half of the water has gone, then transfer to a bain-marie (to stop it "burning") and continue until only 10% is left. I then strain out all the bits through some muslin and add sugar to form the syrup. You can reduce it all the way to a syrup (less than 2% of what you started with!) without adding the sugar but the flavour is far too strong and bitter for most people.

So how do you go about collecting this arcane ingredient? First, of course, you will need to find some mature silver birch trees with trunks at least 25cm in diameter (downy birch won't work) and obtain permission to drill holes in them from the owner – not always easy. (The ones outside the Tate Modern in London are too small, by the way).

You'll also need some kit. A hand drill and drill bit, a bucket to collect the sap (I sometimes use a four litre milk container with a hole strategically cut in the side near the top), some tapered wooden plugs (candle waxed at the sharper end to seal them), a mallet and something to carry the sap home in.

You will also need some spigots or spiles. These are virtually impossible to obtain in the UK so you will have to find them online from Canada or the US where they are uses for sugar maple tapping. You can rig up something with tubes and pipes but I have never been able to stop it all leaking. Check, using a scrap of wood, that your plugs and spiles tightly match the drill bit you will be taking with you.

Off to the woods. Drill a slightly upward slanting 5cm deep hole into your chosen tree at waist height. If nothing comes out when you are half way in, the tree is dry. Stop drilling, hammer in a plug and try another tree. After three no-shows it will be worth waiting another week. If all is well, hammer in a spile, hook on your bucket through the little hole you will have made in the rim and cover it. Come back the next day to collect your sap – if you are lucky you will get about two to three litres from each tree. Very carefully plug the holes – if you don't the sap will continue to flow and the poor tree may not recover from this added insult.

Birch sap tastes almost exactly like water – but the freshest water you have ever tasted, with just a hint of sweetness (0.7% sugar is the highest I have ever found). It does not keep very long – about four days in the fridge – so use it as soon as you can. Here is how you make the wine.

4.5 litres of birch sap
200ml white grape juice concentrate
Juice from two lemons
1.2 kg white sugar
Sachet white wine yeast
Yeast nutrient – follow instructions on packet

Gently heat the sap in a pan with the lid on to 75C and keep at that temperature for 20 minutes. Take off the heat and stir in the sugar until it is dissolved. Closely cover the pan and allow to cool. Transfer to a fermentation bucket and add the lemon juice, grape juice concentrate, yeast and yeast nutrients.

Keep the bucket closely covered for five days then siphon into a demi-john, fit the bubble-trap and leave for about two months. Rack-off into a fresh demi-john and bottle when it is all nice and clear. This stuff goes bad for a pastime, so be extra careful making sure everything is sterile and the bottles well sealed.

The flavour? Light, dry, fruity, with a faint piquancy of wet paper bag.