The seeding rate is the weight of the seed planted per unit area of land for any crop. Typical seeding rates range from a few pounds per acre to over 100 lbs/acre.

The crop yield is the weight of the produce from a harvested crop. In many cases, the produce is itself a seed that can be replanted. Wheat, rice, corn, barley, potatoes, beans, and of course various edible seeds can each be planted to produce a second crop.

A crop cycle is one season for a particular crop, ending with harvesting. Some crops have a short cycle lasting only two or three months. Other crops require many months for each crop cycle. Tree crops often produce only one harvest per year, so they have a crop cycle of 12 months.

Suppose you have a small amount of seed for a particular crop, but you wish to plant a large area. One solution is to do a grow-out. You plant all the seed, harvest the crop when it is mature, and then use the seed from that harvest for a subsequent larger planting. In a grow-out, you plant a crop in order to produce seed for a second crop. The grow out ratio tells us the increase in seed due to one crop cycle.