This afternoon I was privileged to collect and drink sap from a mature birch tree in a friend’s Amsterdam garden.   Today’s tapping was something of an experiment, the process went quite smoothly and we managed to collect about 75ml of Birch Sap (Birch Blood) in about 20 minutes.  I shall certainly be trying it again on other trees, hopefully this spring.

[If you would like to learn more about this in practice, check out my blended learning apprenticeship course.]

Allergic to apples = allergic to Birch
It seems that those with an allergy to apples are very likely to be allergic to Birch sap and thus should avoid it.

Benefits of drinking Birch blood
Birch blood or sap is a weak solution of nutrients which were stored in the roots over winter and are pumped up through the trunk and branches in spring, for the tree to use in new growth.  The sap is drawn upwards through a system of vascular cells, from roots to crown by osmotic pressure. It is mainly water and contains some vitamins (mainly C), minerals (mainly potassium, calcium, magnesium and zinc), amino acids, fructose, glucose and other fruit sugars.  It is clear (not blood red), has a slightly soapy appearance when shaken and has a refreshing watery taste with a hint of birch aroma, a little sweetness and perhaps little bitterness in the aftertaste.  Some say it can taste slightly of Wintergreen, I’m not sure I could taste that today but there was certainly more to it than water.  Sugar content in Birch blood peaks in the middle if the tapping season.

Across cultures, there are a great many health claims associated with drinking Birch sap.  It is said by many to be an excellent spring tonic, to help prevent scurvy and rickets, to help relieve rheumatoid arthritis and gout symptoms, to ease symptoms of multiple sclerosis, to accelerate the metabolism, to help with diabetes myelitis, to help kidney disorders and to cure birch pollen allergy symptoms.  That’s quite a reputation to live up to!

I recommend Hedgerow Medicine by Julie & Matthew Bruton-Seal for further information about the virtues of Birch.

Which birch trees and when?
Sap should only be collected from healthy birch trees, with a base trunk diameter of at least 25cm.  The owner’s permission should be obtained before attempting to collect any sap and care should be taken to prevent further damage to the tree during and after tapping.  If drilling a hole, use a very clean drill bit and insert very clean collection materials.

If you can reach the branch tips of a birch tree in spring, you could break off the tip of a twig and watch for dripping sap.  If it happens quickly, this is a good sign that the sap is flowing well and that it may be possible to collect from the trunk.  Spring time, before the leaves form, is the best time to collect birch sap.  Some say that the best time to collect is when the nights are cold (below zero) and the days are warm.  The tapping season varies depending upon climatic region but it generally only lasts for a month or so.

Some say the same tree can be tapped yearly, others say no more than once every three years.  Be cautious and look after the tree.  One tree can be tapped continuously through one season (change the collection vessel regularly of course).

How to tap Birch Blood
(I used a cordless drill (thank you Herman!), part of an old but tidy metal olive oil spout, 1 meter of aquarium tubing from my local pet shop (cost 1€) or find it here on Amazon, used plastic baby milk bottles for sap collection and an old plastic tub to stop the baby bottle falling over).

1. You must get the permission of the land owner first.
2. The tree must have a trunk diameter of at least 25 cm and must be healthy and strong.
3. Ask permission mentally or audibly of the tree itself.  If you are inclined as I am, then discretely make an offering of something precious to you and natural, to the roots of the tree.  You are taking some of it’s life force so be respectful, careful and only take what you need.
4. Between 50cm and 1 meter up the trunk, drill a 1 inch deep hole through the bark, at a slight upward angle (about 30 degrees) with a very clean drill bit (about 6mm diameter bit).
5. The sap will immediately or very soon start to flow out of the hole.
6. Insert sterile, sturdy but flexible tubing (about 1 meter long), of the same diameter as the hole (this will be a little bigger than the bit size) into the hole.  Like me, you may like to insert a graduated metal tube into the hole to ensure a good seal and then fit flexible tubing over that short tube.
   N.B. Tubing and collection vessels can be sterilised in various ways; I choose to clean them well in slightly soapy water, then boil in clean water for about 10 minutes, then dry on a clean muslin or tea towel..
7. Insert the flexible tubing into a sterile collection vessel such as a plastic drink bottle.
8. Collect as much sap as required or possible in the time you have available.  If leaving the tapping unattended make sure to cover the collection vessel well (plastic bag and elastic band?) so that insects etc. won’t climb in.
9. Seal the collection vessel and use the sap immediately or refrigerate or freeze.
10. Carefully remove the tubing and or metal spout from the hole. See the following section about sealing or not sealing the wound.
11. Clean your tubing, dry it and store for future use.

To seal or not to seal?
There are differing opinions about whether the hole should be plugged or not after tapping.  Some say the tree should be left with an open hole as it will seal it and heal itself best this way.  Recent research on Maples in Canada, suggests this is the best method.  Others warn against leaving the tree to literally bleed to death with an open wound.  Today we plugged the hole as best we could with a twig of the same diameter as the drilled hole.  It worked fairly well and stemmed most of the flow.  Beeswax is suggested by some as another way to seal the hole, I have not yet tried that.  Others suggest inserting a cork, I tried this before the twig today and it was ineffective; the cork had to be whittled to fit and then became too pliable and weak.

It felt better to seal the hole today, I didn’t like to leave all that beautiful sap running down the trunk, although as the weather is not too warm at present and any seepage from the wound runs down the trunk towards the roots, I can’t really imagine that the loss of sap would cause too many problems for a healthy tree.

An easier way to collect a little sap
Simply cut off the ends of some birch twigs or branches and point the cut ends into a bucket or ease them downwards into a bottle.  Sap will soon start to drip out of the cut ends.

Storing and using the sap
Birch sap should be consumed quickly and stored at refrigerator temperature.  The sap can apparently be frozen for some time.  Birch sap can be made into a delicious wine, be boiled down to make a syrup – rather like maple syrup and can be drunk fresh. I have also heard that some chefs like to make Birch vinegar from the sap.