Blood meal is a traditional, single-ingredient organic fertilizer derived from the dried and powdered blood of animals, typically cattle, a byproduct of the meatpacking industry. This nitrogen-rich soil amendment promotes vigorous plant growth. This guide identifies the specific plants and growth stages that benefit most from this powerful natural supplement, ensuring optimal results.
Understanding Blood Meal’s Nutritional Profile
The primary benefit of blood meal is its extremely high nitrogen content, often represented by an NPK ratio of 12-0-0 or higher. This makes it one of the most concentrated sources of organic nitrogen available. Nitrogen is a foundational macronutrient essential for producing chlorophyll, the green pigment responsible for converting light into energy during photosynthesis.
The nitrogen is fast-acting because soil microbes quickly break down the organic compounds, releasing forms plants can readily absorb. This rapid availability effectively addresses immediate nitrogen deficiencies, which manifest as yellowing lower leaves or stunted growth. Blood meal also provides iron, a micronutrient necessary for chlorophyll formation. The combination of readily available nitrogen and iron supports the development of deep green, lush foliage.
Plants Requiring High Nitrogen Input
Blood meal is ideally suited for plants that prioritize vegetative growth—the development of leaves and stems—over fruit or root formation in their early stages. These high-nitrogen feeders include most leafy green vegetables, which require significant nitrogen to produce abundant, vibrant leaves.
Leafy Greens and Heavy Feeders
Specific examples include spinach, kale, lettuce, and cabbage, all of which thrive with a nitrogen boost for rapid growth and deep coloration. Heavy-feeding annual vegetables are another category that benefits greatly. Crops like corn, broccoli, and the brassica family (cauliflower and Brussels sprouts) require nitrogen early in the season to establish strong stalks and foliage. Other heavy feeders like squash, cucumbers, and melons benefit from an early application to build a robust plant structure capable of supporting heavy fruit loads later.
Transplants and Acid-Loving Plants
Young transplants of nearly any variety benefit from blood meal to quickly establish a strong root system and overcome transplant shock. A quick infusion of nitrogen helps the plant focus energy on producing new, healthy shoots and leaves immediately after being placed in the garden soil. This is useful for crops with a short growing season where rapid development is important.
Certain acid-loving plants that often struggle with iron and nitrogen uptake in higher pH soils also respond well. Plants such as blueberries, rhododendrons, and azaleas appreciate the slight acidifying effect combined with the nitrogen and iron content, which encourages healthy, green leaves and helps prevent chlorosis.
Application Guidance and Safety
The concentrated nature of blood meal requires careful application to avoid damaging plants. A general guideline for garden beds is to apply one to two pounds per 100 square feet. For individual plants, a light application of one teaspoon per plant, or one to two tablespoons per square foot around the base, is often sufficient. Always refer to the specific instructions on the product packaging, as concentrations can vary between brands.
Blood meal can be applied by mixing it into the soil before planting new starts or as a side-dressing for established plants. When side-dressing, sprinkle the powder a few inches away from the plant stem and avoid direct contact with foliage or roots. Immediate and thorough watering after application is necessary; this helps dissolve the fertilizer and move the nutrients into the root zone, reducing the risk of chemical burn.
The primary safety concern is “nitrogen burn” due to its high concentration. Excessive application can damage plant roots and foliage, causing leaves to yellow or brown at the edges, and in severe cases, it can kill the plant. Applying too much can also attract animals like dogs, cats, and raccoons who are drawn to the scent of blood and may dig up the garden.
When to Skip Blood Meal
While blood meal is beneficial for leafy growth, its high nitrogen content makes it unsuitable for plants where the goal is fruit, flower, or root development. Too much nitrogen encourages the plant to invest energy into producing foliage at the expense of reproductive structures. This often results in a large, lush plant with few or no blooms and minimal yield, a problem known as the “all leaves, no fruit” effect.
Root vegetables should generally not receive blood meal. Crops such as carrots, radishes, potatoes, and parsnips need balanced nutrition to focus their growth underground. Applying a high-nitrogen fertilizer will encourage prolific, bushy green tops while inhibiting the development and sizing of the edible roots.
Established perennial plants that are already healthy and low-feeding, or those nearing their flowering or fruiting stage, also do not require this intense nitrogen boost. Once a plant has reached its mature vegetative size and is preparing to set fruit, a fertilizer with a higher phosphorus and potassium ratio is typically more appropriate. Using blood meal on young seedlings should be approached with caution, as its potency can be overwhelming.