Flax, added by RedPower 2, is a plant that can be farmed and will yield String rather than Wheat. Flax Seeds can be obtained by breaking tall grass, similar to regular seeds. Farming is also similar to wheat farming, except that flax can only be planted on hydrated Farmland. Breaking the mature plant will give you some seeds and string. For optimum drops, use a Sickle. Harvesting without a Sickle will cause Flax to drop approximately 2-3 String and 2-3 Flax Seeds. Harvesting with a Sickle will cause the Flax to drop between 3-4 Flax Seeds and around 4-5 String.
A flax plant cannot have Bone Meal applied to it if it is past its initial stage of growth. This crop is similar to Sugar Cane in regards to harvesting: as long as the bottom portion of the plant remains intact, the plant will regrow*.
*Although flax may be intended to grow like Sugar Cane, a bug in Tekkit Lite prevents this from happening. The top block can be broken separately from the bottom block; however, the if only the top block is broken, it will not grow back. In order to grow another top for more string, an entirely new flax plant must be planted.