I use this pattern optimized for space:
cccccc...
cwccwc...
cccccc...
c = crop, w = water
Use scythe to harvest and you get two. Still i find cultivation impractical at least in single player, it just takes too long time and just to get 2 per plant.. if u want more seeds takes 5 to make a seed, and then the food needs a lot of materials... perhaps i havent found the "proper way" either tho