Gradient System Acting on the laws of nature, the EarthBox facilitates the movement of nutrients from areas of high concentration to areas of low concentration. When the EarthBox is set up, the fertilizer stripe is placed on top of the potting mix-creating an area of high nutrient concentration. At this time, the potting mix around the roots of the growing plant has no fertilizer. When water is added, the moist potting mix slowly conducts the diluted nutrients down the concentration gradient to the plant roots,which absorb optimal amounts of nutrients at any given time.

Water and Fertilizer Conservation The EarthBox's plastic cover drastically reduces the water evaporation rate and returns condensed water vapor to the potting mix. As the plants draw water from the reservoir, they consume only what they need to stay healthy. Plants cannot be over-watered or under-watered if the reservoir is kept full. The plastic cover also prevents fertilizer from being diluted or washed away by rain. From Earthbox.com