How to Use the Compost & Fertilizer Calculator
Guessing how much compost and fertilizer to apply often leads to underfed plants that struggle to grow, or overfeeding that can burn roots. Enter your garden area and the type of crop you're growing (leafy greens, fruiting crops, or root vegetables), and this calculator applies standard home-garden rates to give you the compost and fertilizer amounts you need.
Different crops need different nutrients. Leafy greens, grown for their foliage, have relatively high nitrogen needs; fruiting crops need more phosphorus and potassium to support flowering and fruit set; and root vegetables actually do worse with too much nitrogen, since it pushes leaf growth at the expense of root development, so their rates are set lower. Compost works as a base dressing that improves soil structure and releases nutrients slowly, while fertilizer supplies faster-acting nutrients.
If you're new to vegetable gardening or have never been sure how much to apply each season, use this calculator to get a solid starting point, then fine-tune based on an actual soil test if one is available.
Frequently Asked Questions
Leafy greens, fruiting crops, and root vegetables each need different nutrient amounts, so standard application rates vary by type.
Compost improves soil structure and releases nutrients slowly, while fertilizer supplies nutrients quickly. Using both gives a balanced feeding program.
These are standard rates for typical garden soil, so adjust based on your soil test, but stay close to the calculated range for best results.