So, been having a think, and researching… I found a good article here:

It is extolling the virtues of growing naughty stuff, but it does suggest that there is research in the US pointing to an average 10-15 times the yield in indoor agriculture (including vine plants such as tomatoes), as opposed to their soil grown counterparts. About 63% is from bigger yields, i.e. nutrient control, extra forced sunshine hours. With the remaining 37% coming from increased crop turns. So my theory about skipping winter is probably right. 1/4 of the year, which is 1/3 of the remainder.

Anyway, now the focus must be on the nutrients to give the vines. My material for the pot is going to consist of sand, course gravel, and clay pebbles with a minimal amount of soil and worm castings*. The friable surface will be covered in loose gravel. I expect this to allow the water and nutrients to pass through with relative ease. With good enough retention to offer nutrition constantly.

Worm castings are very good sources of nitrogen, now I will need to be very careful with how much I use… As too much nitrogen is really bad for vines. However, I also figure, my vine is in a pot with very little actual soil…

A normal vineyard would have anywhere between around 10 to 70 worms (per sqft) in the soil, each producing 68g of castings a month. I believe that without being overzealous a sensible level of worms in a vineyard would be 35 per sqft? So 35 x 68g means for each month we should use equivalence of 2380g of worm castings.

Nutritionally worm casts, OK, its basically worm manure… Have an NPK of anywhere between 1-0-0 and 3-1-1. This may seem a risky strategy, adding a lot of nitrogen into the diet of my vine. However looking at the bigger picture and how many worms should be in the soil… It gives us a quantity of nitrogen to add each month, the effective replacement of the nitrogen contained in 2380g of worm castings.

So where should we get our other nutrients from? Well kelp extract or effectively seaweed concentrate holds the answer for potassium, as it has an NPK of about 1-0-4 on average. Making it a good trace mineral.

So now we have a supply of Nitrogen and Potassium, but I still need to find a source of Phosphate… Back later.