Beets should be fertilized prior to planting and additionally after the plant has reached 3” in height.
Beets Soil pH Requirements
To understand exactly what additional nutrients beets will require, you should always perform a soil test and base the fertilizing and pH decisions on the results.
Beets will tolerate soils with a pH range of 6.0 to 7.5 but will perform best in soils with a pH of 6.2 to 6.8. They will not perform well in acidic soils that are lower than 6.0 so you will need to raise or lower the Ph of the soil accordingly.
Initially Fertilizing Beets
In the absence of a test, you can fertilize the soil prior to planting your beets. Work in two to three inches of compost then add a 5-10-10 fertilizer at a rate of two pounds per one-hundred square feet to the soil that is worked to a depth of six inches.
The plants can be fertilized again when they reach 3” in height. The second round of fertilizer should be lighter than the initial one at half-pound per one-hundred square feet.
When fertilizing live growth, side dress at least 3” around the plant paying careful attention not to fertilize the plant directly. Irrigate the soil thoroughly following fertilization.
If you notice black, sunken spots on your beets, this indicates a boron deficiency. You may need to supplement as needed.
Drost, Don, and Wade Bitner. “Beets in the Garden.” Utah State University Cooperative Extension. N.p., n.d. Web. 26 Feb. 2014. <http://extension.usu.edu/files/publications/publication/HG_2004-11.pdf>.
“Ohio State University Extension Fact Sheet.” Growing Beets in the Home Garden, HYG-1604-93. N.p., n.d. Web. 26 Feb. 2014. <http://ohioline.osu.edu/hyg-fact/1000/1604.html>.