Blood meal is dried, powdered bovine blood — a byproduct of USDA-inspected meat processing facilities. The blood is collected, spray-dried or flash-dried at high temperature, and milled into a fine powder. The drying process kills pathogens and concentrates the protein, yielding approximately 13% nitrogen by weight. It has been used as an organic nitrogen source for centuries and remains one of the more concentrated organic amendments available to gardeners.

Blood meal's nitrogen is bound in protein chains. Soil bacteria must break down these proteins into amino acids and then into ammonium before plants can absorb them. In warm, moist, biologically active soil, nitrogen often begins becoming available within 1–3 weeks, with benefits commonly extending for several weeks after that. Lab incubation studies show that more than 80% of the applied nitrogen mineralizes within a single growing season under favorable conditions — a much higher fraction than feather meal or alfalfa meal. Release slows significantly in cold soil. For more on how nitrogen functions in plants, see the function of nitrogen in plants.

For tomatoes during the vegetative phase, 1–2 teaspoons per plant worked into the top layer of soil is a typical rate (OSU Extension EC 1503 per-plant guidance). Do not apply once flower buds appear — excess nitrogen at that stage can push leafy growth at the expense of fruit set. Once flowering begins, transition to a phosphorus-supportive fertilizer like Bone Meal 3-15-0.

Yes — the scent of blood meal can attract dogs, cats, raccoons, and other animals. To minimize this, work blood meal thoroughly into the top 2–3 inches of soil rather than leaving it on the surface, and water it in immediately after application. Once incorporated and moistened, the scent dissipates more quickly. Store unused product in a sealed container away from pets. If animal access is a persistent issue, consider Alfalfa Meal 2.5-0-2.5 as a lower-odor nitrogen alternative.

Blood meal works best on nitrogen-hungry crops: leafy greens, corn, brassicas, and herbs in their vegetative growth phase. It is not recommended for legumes (beans, peas), which fix their own nitrogen and rarely benefit from added N. For fruiting crops like tomatoes and peppers, use blood meal only during the vegetative phase — reduce or stop applications at the first sign of flower buds. Because blood meal is an animal-origin soil amendment, incorporate it into soil and avoid direct contact with harvestable plant parts for edible crops. For a broader overview, see Best Fertilizers for a Vegetable Garden.

Yes — blood meal is one of the most effective organic compost activators when you have a carbon-heavy pile that won't heat up. Add 1–2 cups per cubic yard mixed evenly into the pile, aiming for a starting C/N ratio around 30:1. Peer-reviewed in-vessel composting research shows that pushing the starting C/N below ~16:1 with too much blood meal causes large ammonia volatilization losses (up to 84% of initial ammoniacal-N) and produces less stable compost — so add it in measured amounts rather than dumping a full bag.

Blood meal is not a pH management product, but the ammonium-N it releases is mildly acidifying as it nitrifies in soil — similar to other ammonium-form nitrogen sources but at a much smaller scale. If your soil is already acidic (below pH 6.0), nitrogen mineralization can slow, and periodic soil testing helps catch any drift. For acidic soils, Dolomite Lime raises pH and supplies calcium and magnesium. For more on building healthy soil, see our Organic Gardener's Guide to Soil Preparation.

Blood meal is commonly used in certified organic production systems. The 40 lb bag is repackaged from OMRI Listed® material. For food gardens, incorporate it into soil, avoid direct contact with harvestable plant parts, and follow good produce-safety practices for animal-origin soil amendments. Allow it to be watered in thoroughly before harvesting leafy greens. For a broader look at how organic and synthetic fertilizers differ, see our organic vs. synthetic fertilizer comparison.

Blood meal is derived from animal blood, which is naturally very high in protein (and therefore nitrogen) but contains no significant phosphorus or potassium. This is the natural nutrient profile of the source material. Rather than a limitation, use blood meal as a targeted nitrogen amendment and pair it with Bone Meal 3-15-0 for phosphorus and Potassium Sulfate 0-0-53 for potassium when a complete program is needed.

No. Blood meal does not fully dissolve in water — it forms a suspension that will clog sprayers and provides no meaningful leaf-uptake benefit. The nitrogen is protein-bound and requires soil microbial breakdown to become plant-available. For soluble nitrogen options that work well as foliar feeds, see Calcium Nitrate 15.5-0-0 or Urea 46-0-0 (note: not certified organic). For chlorosis on young growth, Chelated Iron EDTA addresses iron deficiency directly via foliar application.

Often yes. Nitrogen is a mobile nutrient in plants, so when a plant runs short of N, it shifts existing nitrogen from older lower leaves to support new growth — producing the classic pattern of yellowing lower leaves with green growing tips. But yellowing has multiple potential causes — iron deficiency yellows new growth (not old), overwatering damages roots and limits all uptake, and pH lockout can mimic deficiency even when N is present. For a full diagnostic walkthrough, see 8 Reasons Why Your Plant Leaves Are Turning Yellow.