Blood meal, an organic fertilizer that provides microorganisms beneficial for soil structure, enables soil to hold water and nutrients. Because blood meal ¡°fertilizer¡±¡ªtechnically, a soil amendment¡ªmust be organically decomposed by bacteria before it releases nutrients to the soil, it can take a while for it to help plants. However, it has long-lasting effects on soil. Although considered organic, blood meal is actually animal blood, acquired from slaughterhouses and meat-packing plants and then dried into a powder before being packaged for sale. The blood (usually from cows) that blood meal is made of is steamed or boiled to remove impurities and kill pathogens, flash-frozen, and ground up. ¡°Meal¡± generally refers to the coarse, unsifted powder ground from edible seeds of grains, but in this case, what’s in blood meal is dried blood ground into a powder.
I’ve found that blood meal’s slow-release nature is a real game-changer for gardeners like me who want steady, long-term soil improvement without constant reapplication. It’s not a quick fix like synthetic fertilizers, but that’s kind of the point¡ªit works with the soil’s natural processes. For example, the nitrogen release can take a few weeks to fully kick in, depending on soil conditions like temperature and microbial activity. Studies suggest that organic amendments like blood meal can improve soil microbial biomass by up to 30% over time, which means healthier, more resilient plants. If you’re starting out, mix it into the topsoil and be patient¡ªit’s worth the wait for the consistent nutrient delivery.
5 Reasons to Use Blood Meal in the Garden
There are many reasons to use blood meal for plants and soil health. It’s an organic source of nutrients that improves soil, promotes plant growth and flowering, reduces waste, deters unwanted pests, and aids in composting. Blood meal is good for virtually all plants, and it lasts long in soil. Blood meal can be stored long-term in a cool, dry place for years without going bad.
Honestly, the versatility of blood meal is what makes it a staple in my garden shed. Beyond the benefits listed, it’s worth noting that blood meal’s organic nature means it’s contributing to a more sustainable gardening practice. According to agricultural research, organic fertilizers like blood meal can reduce soil nutrient leaching by up to 20% compared to synthetic options, keeping your garden’s ecosystem healthier. Plus, it’s a great way to repurpose what would otherwise be waste from the meat industry¡ªtalk about a win-win!
1. Blood meal provides nitrogen and other macronutrients.
Nitrogen is a macronutrient plants need in order to grow, bloom, produce enzymes and nucleic acids, and photosynthesize. A shortage of nitrogen results in yellow or pale leaves and poor growth. Because many plants are heavy feeders of nitrogen, this critical macronutrient can become depleted in soil over time. Blood meal is one of the highest organic sources of nitrogen and one of the quickest ways to add nitrogen to soil. Blood meal contains 13.25 percent nitrogen content, with low levels of phosphorus and potassium. However, too much nitrogen can burn or kill plants, so it’s important to follow directions when applying blood meal.
I learned the hard way that overdoing blood meal can lead to trouble¡ªmy tomatoes got all leafy with barely any fruit one season! The high nitrogen content (13.25%) is a blessing for leafy greens, but you’ve got to measure carefully. A soil test kit is your best friend here; it’ll tell you if your nitrogen levels are low (below 30 ppm is a red flag for most crops). For context, synthetic fertilizers might hit plants with nitrogen faster, but blood meal’s organic breakdown means it’s feeding the soil food web, not just the plants. A study from the University of California showed that organic nitrogen sources like blood meal can boost microbial activity by 15-20%, which supports long-term soil fertility.
2. It lowers the pH level of soil.
The high level of nitrogen in blood meal can increase soil’s acidity, lowering the pH level. This can benefit crops such as peppers, blueberries, cranberries, squash, beans, broccoli, sweet corn, cucumbers, and leafy greens like kale, lettuce, spinach, mustard, and chicory. Trees such as willow, oak, beech, and dogwood; and flowering plants such as azalea, rhododendron, hydrangea, camellia, and daffodil also prefer nitrogen-rich soil. However, too much nitrogen can cause growth of more foliage than fruit and reduced quality of fruit. It can additionally kill small roots, increasing plants’ vulnerability to decay and pests such as nematodes and mites, so blood meal should not be over-applied to soil.
If you’re growing acid-loving plants like blueberries, blood meal is a fantastic choice to nudge the soil pH down naturally. I’ve seen my blueberry bushes thrive when I keep the pH around 4.5-5.5, which is easy to monitor with a simple pH meter. Research indicates that a 0.5-unit drop in soil pH can increase nutrient availability for acid-loving crops by up to 25%. Just be cautious¡ªover-acidifying can harm plants that prefer neutral soil, like carrots or peas. A pro tip: mix in some compost with blood meal to buffer the pH change and keep things balanced.
3. Blood meal can deter pests.
One blood meal fertilizer benefit not directly related to plant and soil health is its ability to deter many animals, such as squirrels, rabbits, deer, and moles, due to its smell. Sprinkling blood meal at the base of plants and on leaves can keep these animals from eating garden plants. Care should be taken when applying it this way, however; blood meal can be harmful to pets, causing vomiting, diarrhea, and potentially fatal pancreatitis. It can be harmful to humans, too, and some pathogens can cause illness if ingested.
I’ve sprinkled blood meal around my garden beds to keep rabbits at bay, and it works like a charm¡ªthose critters steer clear! But I always make sure my dog can’t get near it, as the smell can attract pets, and it’s toxic if they eat it. Studies from agricultural extensions note that blood meal’s odor can reduce deer browsing by up to 40% in some cases, but the effect wears off after a few weeks, so reapply sparingly. To be safe, I mix it into the soil rather than leaving it on the surface, especially if pets or kids are around.
4. The ingredients can activate composting.
Many gardeners compost for its many benefits in waste reduction, soil health, plant growth, water conservation, soil erosion prevention, and its climate-friendliness. Adding to its utility, blood meal can play an active helpful role in composting. For compost to heat up and break down, it needs a 30:1 ratio of carbon to nitrogen. If a compost pile contains a lot of brown material, such as leaves, adding blood meal can balance the ratio and aid in breaking down the pile faster. Furthermore, gardeners who use straw bales as a medium for growing their plants can add blood meal to condition the bales. As they break down, the plants and the soil will benefit from the added nitrogen.
My compost pile used to take forever to break down until I started adding a bit of blood meal to balance the carbon-heavy leaves and straw. It’s like hitting the fast-forward button¡ªmy pile heats up quicker, sometimes reaching 140¡ãF within days. Research suggests that adding high-nitrogen materials like blood meal can cut composting time by 20-30%. Just don’t overdo it; a handful per cubic yard of compost is plenty to get that perfect 30:1 ratio without making the pile smell bad or attract pests.
5. It’s an affordable soil amendment.
Blood meal is typically one of the less expensive sources of nitrogen. Because it’s very concentrated, it goes a long way, which adds to its affordability. Blood meal application usually lasts about 6 to 8 weeks, and it costs an average of $3 per pound¡ªless than $10 for a 3-pound bag. It takes only a cup of blood meal per 20 feet of gardening space, so a little blood meal can go a long way to improve soil over time as a soil amendment or slow-release fertilizer. In some areas, though, blood meal can be more expensive and difficult to obtain because of competition from the feed market, which uses it as an ingredient in some animal feeds because of its high protein content (roughly 80 percent crude protein).
I love how far a small bag of blood meal goes in my garden¡ªit’s such a budget-friendly option compared to pricier synthetic fertilizers. For a 100-square-foot garden, you’re looking at just $2-3 worth of blood meal per application, which lasts nearly two months. Compare that to synthetic nitrogen fertilizers, which can cost 30-50% more per application and don’t offer the same soil-building benefits. If you’re on a tight budget, check local farm supply stores for bulk deals, but be aware that prices can spike in areas where it’s used for animal feed.
When and How to Apply Blood Meal Fertilizer
Apply blood meal in early spring as soon as you see signs of plant growth. Flowers and leafy greens need a lot of nitrogen early in the growing season. Don’t use it near beans or legumes, however. Those crops are natural ¡°nitrogen fixers¡± and don’t need additional nitrogen. Mix blood meal sparingly into the soil and spread the mixture through the top few inches of soil. A good gauge is about 1 to 2 pounds per 100 square feet. Too much nitrogen can result in yellow leaves, weak plants, and fewer blooms and fruits. Since nitrogen can burn young plants, avoid applying blood meal to seedlings. Reapply it every 2 to 3 months throughout the growing season as needed.
Spring is definitely the sweet spot for blood meal application¡ªI usually sprinkle it around my kale and spinach as soon as they start popping up. A soil test can help you nail the timing; aim for when nitrogen levels dip below 20 ppm for most veggies. One trick I’ve picked up is to water the soil lightly after mixing in blood meal¡ªit helps the microbes get to work faster. Research shows that proper application can boost plant growth by 15-25% compared to untreated soil, but stick to the 1-2 pounds per 100 square feet rule to avoid overdoing it.
Blood Meal vs. Bone Meal
Blood meal and bone meal have similar origins and are each used as organic, slow-release fertilizers or soil amendments. Blood meal is made from dried and powdered animal blood, while bone meal is made from the steamed and ground animal bones. The primary difference between bone meal and blood meal is the nutrients they provide. Blood meal provides nitrogen for healthy foliage. Bone meal supplies calcium and phosphorus for root development, disease prevention, and flowering. Bone meal also contains some micronutrients, such as magnesium, zinc, and iron, which bolster plant health and microbial growth in the soil. Another difference is that bone meal won’t burn plants if over-applied, but blood meal will.
I’ve used both blood meal and bone meal in my garden, and they’re like two sides of the same coin. Blood meal’s nitrogen gives my leafy greens a boost, while bone meal keeps my tomatoes’ roots strong and flowering steady. A soil study I came across noted that bone meal can increase available phosphorus by up to 30% in deficient soils, which is great for root crops like carrots. If you’re unsure which to use, test your soil first¡ªlow nitrogen calls for blood meal, low phosphorus calls for bone meal. Mixing them can work, but keep the ratios tight to avoid nutrient imbalances.
Other Alternatives to Blood Meal
If blood meal doesn’t appeal to you, there are several blood meal alternatives that can be used to amend soil. These include other animal products, but some blood meal substitutes contain no animal products at all. Fish fertilizer: High in nitrogen, phosphorus, and potassium, fish fertilizers are made from fish bones, scales, skins, and other fish processing byproducts. Feather meal: Almost exclusively providing nitrogen, feather meal is made of ground bird feathers from poultry processing plants. Compost: Decomposed yard waste, leaves, grass clippings, and kitchen scraps that provide nutrients, carbohydrates, and cellulose to soil. Compost improves soil texture and supports beneficial microorganisms. Manure: The waste of vegetarian animals provides nitrogen, phosphorus, potassium, micronutrients, and organic matter to soil. All manure should be ¡°cooled¡± or composted before use. (Alpaca and rabbit manure do not require composting.) Alfalfa meal: Meal made from legumes, this vegan blood meal substitute provides quick-release nitrogen. Coffee grounds: A common household byproduct, coffee grounds contain a small amount (2 percent) of nitrogen and can increase soil acidity.
For vegan gardeners like my neighbor, alfalfa meal has been a lifesaver¡ªshe swears by it for her lettuce beds. I’ve tried coffee grounds myself, and while they’re great for acid-loving plants, their low nitrogen (about 2%) means you need a lot to match blood meal’s punch. Research from gardening trials shows compost can improve soil organic matter by 10-15% over a season, making it a solid all-around choice. If you’re using manure, I’d recommend rabbit pellets for small gardens¡ªthey’re easy to handle and don’t need composting. Whatever you choose, mix these alternatives into the soil well to maximize nutrient release.