Most plants need very little boron, averaging about 50 ppm in dry weight tissues. When a deficiency is noticed, the plant can be sprayed with a very dilute spray of borax and water, but the spray does not always work. Another option is to mix a fresh batch of nutrient water, or to add about 1 gram of borax per 10 gallons of water. Boron toxicity Too much boron can be toxic to the plant, and toxicity resembles boron or calcium deficiency. Leaf edges to start to die, and the plant leaves lose chlorophyll.
Seeds fail to sprout and leaf points die prematurely.
Root growth is restricted and surfaces of root vegetables are often ruptured. Boron occurs extensively in animal tissues but its role is not clear. If boron has a similar role in humans, boron may assist in the uptake of calcium. Human requirements for boron No boron requirement or allowance has been set for humans. When diluted into water at 100 to one, these change to 20 to 2 ppm in the water.