Birch Sap

Spring is here early this year. The days are lengthening, and the sun shines clean and warm. There is still a chill on the breeze to redden the cheeks and prick tears from the eyes. I hear nightingales, all trills and whistles, and a distant cuckoo yoo-hoos from its hiding place.

I see the slim fingers of irises and daffodils point at the sky, and the first dandelions and primroses are popping yellow on the green beneath the hedge. Fat buds are swelling on the fruit trees, the hazel is thick with catkins, and the sap is beginning to rise in the silver birch. Promises of life to come. 

Birch trees are explorers. A pioneer species, they will colonise bare ground where little else grows, sparking an increase in biodiversity. The silver birch (Betula pendula) is the most easily recognisable tree of the birch family. It grows tall though relatively thin, and has silvery-white bark with darker horizontal markings. In the winter and spring, before their triangular leaves appear, the stark colour of the trunks and straggly, drooping branches are easily spotted, especially against a blue sky. On older specimens, the bark around the base of the trunk and further up becomes rough with raised, dark, diamond shapes.

Tapping trees that do not belong to you is legally somewhat dubious, so grow some if you have room (they grow readily and quickly, pioneers that they are), or find a neighbour who is happy for you to drain some sap.

Timing is everything. The sap can rise anywhere from mid-February to mid-April, depending on where you are and the weather conditions. Key is tapping the tree before the leaf-buds fatten and burst into leaf.

To tap your tree, use a drill with a large, clean bit attached. The diameter of the bit depends on your method of guiding the sap from the hole to your chosen receptacle; the hole must be the correct size to hold it tightly in place. I use the plastic tube designed for siphoning booze from fermenting buckets into bottles, and a five-litre food grade plastic bottle. There are spigots or spiles designed for the job, though they are not easy to come by.

Drill a hole, about one metre from the ground, at a slightly upward angle, to about three to five centimetres deep. Do this gently, cleanly, and in stages. At some point clear liquid will begin to run from the hole at a surprising rate. Push your tube into the hole, and place the other end of it into your bottle (make sure the tube is long enough that the bottle may rest on the ground).  Cover any holes where the tube meets the neck of the bottle to prevent insect interlopers, and retire for a day. I’ve found that the tree will produce between three and five litres of sap in a 24 hour period.

There are differing opinions about how long you should tap a tree for in order to avoid damaging it, anywhere from one day to one week. I err on the side of caution and tap for no more than a couple of days – the sap is the life-blood of the tree after all, and it needs it more than I do. It is also wise to only tap individual trees every other year, to let them rest and recuperate.

Once you’ve collected your syrup, remove the tube and plug the hole with a clean cork or wooden plug, or some clay. Again, there is debate over whether or not to plug after tapping and over what material to use if doing so, in regard to the tree’s healing process. I do plug, using the clay soil that my tree grows from. Having respect for the tree and its lifecycle is paramount, whatever you do.

The sap itself is delicious, like the cleanest sweetest water, and there is anecdotal evidence that it has health benefits taken as a tonic. It will only keep in the fridge for a day or so, as it starts to become quite acidic after this. It can be made into wine, or reduced to make a sweet syrup.

You will not get much syrup for your efforts; 10 litres usually offering up a measly 100ml, though I must stress it is worth it.  Pour the sap into a clean wide saucepan, set on a high heat, and bring to a rolling boil. Boil this until around 80% of the water has evaporated, and taste. It will have become sweeter, with a rounder flavour.

Transfer to a metal or glass bowl, and place over a pan of simmering water (not letting the water touch the bottom of the bowl). Allow this to gently evaporate, tasting until you are happy with the level of sweetness. This can take quite a long time, hours in fact.

Continue to evaporate until the liquid becomes darkened, as the sugars caramelise (though be careful as it is easy to burn this). Once it is a golden colour, and syrupy in consistency, it is ready. It is as sweet as you would imagine, with mineral notes and a little acidity; the best way I can describe the flavour is caramel-vanilla-rhubarb.

The syrup will keep in a sealed bottle for a couple of weeks. It is delicious. Use on pancakes, add to cocktails, and make sure you lick the spoon.