Root stimulator products applied soon after planting contain fertilizers and hormones intended to boost root and plant growth for faster establishment in the soil. There is no solid research to support the efficacy of root stimulants, but neither is there research to disprove the claims of the various root stimulants. While the jury is still out, many gardeners apply root stimulator products and claim to see benefits. The amount of root stimulator to use increases with the size of the plants to be treated.
Mix root stimulator at a rate of 3 1/2 tablespoons of root stimulator product to 1 gallon of water or for treating many new plants, mix at a rate of 1 pint of root stimulator to 1 gallon of water.
Pour the diluted root stimulator solution around the root zone of new transplants. Pour the solution on the soil and not directly on the plant stems and leaves. Apply 1 pint of solution per plant for small plants, such as annual flowers, up to 1 foot tall. Use 3 pints of root stimulator solution per plant for plants 1 to 4 feet tall. Use 1 gallon of the root stimulator solution per plant for plants over 4 feet tall. If you are treating a potted plant, apply 1/2 cup of the solution for each quart of soil in the container. For example, a 2-gallon container holds 8 quarts of soil, so you apply 4 cups of root stimulator solution to the container.
Reapply new root stimulator solution once every two weeks for the first six months after transplanting. If a plant that was 6 inches at planting time, requiring 1 pint of root stimulator solution, grows to 2 feet tall after a few months, increase the amount of solution to 3 pints per application.