What nutrients do carrots need?
Written by
Michael Sullivan
Reviewed by
Prof. Charles Hartman, Ph.D.How to grow carrots that are nutritionally optimized requires a balance of nitrogen, phosphorus, and potassium (N, P, K). I figured all this out after my first crop of carrots grew lush greens but the roots were puny in comparison. Carrots need additional amounts of phosphorus for root development, too much nitrogen will result in true tops and bitter flavor.
Primary Nutrients
- Nitrogen (N): 5-10% for initial leaf growth
- Phosphorus (P): 10-15% for root expansion
- Potassium (K): 10-15% for disease resistance
Micronutrients
- Boron: Prevents hollow heart disorder
- Calcium: Strengthens cell walls
- Magnesium: Aids chlorophyll production
To remedy boron deficient crops use either a kelp meal treatment or a borax solution. My carrots had developed brown cracks until I started spraying 1 tbsp of borax per gallon of water once a month. Before adding any boron to your soil make sure you've tested the soil pH first because boron can be toxic in soils with a pH below 6.0. Using compost tea is a more forgiving micronutrient booster.
Feed your carrots in the spring with bone meal (0-12-0) for root development, and your fall crops benefit from a sprinkling of wood ash for potassium. I typically mix any used coffee grounds into the beds before planting (as they contain about 2% nitrogen). They might slightly acidify the soil, but they still feed the soil and deter pests on the surface because of their acidity.
Read the full article: How to Grow Carrots: Complete Guide for Beginners
