Ore reeds can't grow on just any old block. They must be planted on ore essence (the black one) or gem essence (the white one), and they need to be planted next to lava to get all the nutrients they need to grow. Diamonds, emeralds, lapis, gold, ender pearls, and blaze rods all need to be planted on gem essence. Coal, iron, redstone, nether quartz, glowstone, obsidian and clay can all grow on either ore essence or gem essence. An ore reed takes on average 36 minutes to grow, twice as long as sugarcane.
So how do you make these blocks and reeds?
For the essences, shapeless crafting like so:
Ore essence must be made with coal and not charcoal.
To make the reeds, use shaped crafting like so:
Finally, when you've grown your reeds and want to turn them back into something useful, use these (shaped crafting) patterns:
Diamond, emerald, iron, gold, ender pearls and blaze rods all take 8 reeds to make, in the pattern shown above. Coal, lapis, obsidian, and nether quartz need 4, and redstone, glowstone dust, and a clay ball can each be crafted from a single reed.
The source code is on github.
If you want a similar but easier mod, consider Ore Canes instead.
This mod was inspired by B0bGary's Growable Ores, which sadly was never updated past 1.7.