In medieval times, almond milk was a substitute for animal milk, which had to be quickly converted to butter or cheese to store it. Almond milk could be produced as required too, unlike animal milk, which is a more long-term undertaking, as you need a female sheep/goat/cow/nak/buffalo/horse or whatever to produce its young first before you can obtain the milk.

For the ultimate in self sufficiency from a small plot, and for vegans, you could make almond milk yourself. We haven't tried this ourselves yet, but this is what we were told at a medieval re-enactment event a while ago. Just take any volume of sweet almonds (take care; do NOT use bitter almonds, which are a different nut and very poisonous), grind them, add twice their volume of water (boiling), leave 5-10 minutes, sieve out the bits, or use a blender to mix it all well together. Medieval recipes give the details. Additionally, the Almond Board of California gives a recipe using blanched almonds, roasting them for extra flavour and while warm, adding four times their volume of water, plus some vanilla or honey flavouring, and leaving this in the fridge for a day before blending and sieving.

To grow your own almonds, choose a sweet almond variety (Prunus dulcis dulcis), NOT the (poisonous) bitter almond (Prunus amygdalus amara). Almonds are frequently grown as ornamental flowering trees because they do not crop well in all areas (they are hardy in zones 8-10 but early blossoms can be killed), so some sellers may not distinguish between the two types. Be sure to buy from a knowledgeable nursery and seek their advice on the likelihood of it cropping in your area.

Almonds should bear nuts on three to four-year old trees. Spread a net below the tree and tap the branches, or wait until the nuts fall naturally (early October in southern England, a week or so later elsewhere). The husks will be split if fallen naturally, so remove these and dry the nuts in a well ventilated place, in sunshine or an airing cupboard. If you need to beat the squirrels, harvest earlier, start off drying the complete nut until you can split off the husk and then continue to dry the nut.

This page has information on growing ingredients for muesli: almond milk, almonds.