The question of whether blood helps plants grow generally refers to blood meal, a dried, powdered fertilizer byproduct from animal processing, most often from cattle. This material is highly beneficial for plant growth due to its extremely high concentration of nitrogen. As a natural, organic amendment, blood meal is a popular choice for gardeners seeking to enrich their soil and boost the health of crops. Understanding its proper usage is key to harnessing its powerful effects in the garden.
The Primary Nutrient Contribution
Blood meal is an exceptionally rich source of nitrogen, functioning as a powerful plant food. The typical nutrient analysis, or NPK ratio, is around 12-0-0 or 13-0-0, meaning it contains 12% to 13% nitrogen with almost no phosphorus or potassium. This high nitrogen content makes it a fast-acting organic fertilizer, providing an immediate boost to struggling plants.
Nitrogen is a fundamental component of chlorophyll, the pigment responsible for capturing sunlight and converting it into energy through photosynthesis. By boosting nitrogen availability, blood meal encourages rapid vegetative growth, resulting in lush, deep-green foliage and strong stems. Plants displaying signs of a nitrogen deficiency, such as yellowing leaves, can often be restored to health with an application of blood meal.
Proper Application Methods
Blood meal is primarily used to promote leafy growth for heavy nitrogen feeders, such as leafy greens, corn, brassicas, and alliums. It is best applied early in the growing season to support a robust vegetative structure before the plant begins to flower or fruit. For fruiting plants like tomatoes and peppers, a nitrogen boost is beneficial in the early stages, but a switch to a more balanced fertilizer is necessary later to encourage fruit production over excessive leaf growth.
The fertilizer can be applied as a dry powder or as a liquid feed. To apply dry, it should be mixed lightly into the top few inches of the soil surface to ensure the nutrients are available to the roots. A common guideline for garden beds is to use about one to two pounds per 100 square feet. For established plants, it can be side-dressed by applying one to two tablespoons around the base, keeping it away from the stem.
For a quick-release liquid application, the powder can be diluted with water, following the manufacturer’s instructions. It is important to water thoroughly after application to help the nutrients break down and move into the soil. Because blood meal releases nitrogen over a period of two to six weeks, reapplication is generally recommended only every two to three months during the active growing season.
Practical Drawbacks and Safety
Due to its high concentration of nitrogen, the most significant risk of using blood meal is over-application, which can result in “nitrogen burn.” Excessive nitrogen damages plant roots and foliage, manifesting as yellowing or browning leaf tips and edges. In severe cases, over-application can kill the plant. This concentrated nutrient can also inhibit the production of flowers and fruits, leading to a plant with abundant leaves but a poor harvest.
Nitrogen-rich fertilizers can contribute to soil acidification. While this is beneficial for acid-loving plants, it can be detrimental if the soil is already low in pH. Gardeners should consider performing a soil test before application to determine existing nutrient levels and pH.
The strong, distinct odor of the dried blood can attract scavenging animals. Dogs, raccoons, and other omnivores may be drawn to the scent and dig up garden beds. For safety, the product should be stored securely and applied by mixing it well into the soil rather than leaving it on the surface.