Blood meal is a byproduct of animal processing, consisting of dried and powdered animal blood used as an organic fertilizer. It is highly valued for its concentrated nitrogen content, which provides a quick and robust nutritional boost for plants. This article evaluates the effectiveness and practicality of using blood meal specifically for growing potatoes. Understanding how this high-nitrogen source interacts with the potato plant’s vegetative and tuber development phases is key to successful application.
Nitrogen’s Role in Early Potato Development
Nitrogen is a foundational nutrient for the potato plant, directly fueling the development of the foliage, known as the haulm or vine. This vigorous early growth is necessary because the plant needs a large, healthy canopy of leaves to perform sufficient photosynthesis. A larger, healthier canopy increases the plant’s capacity to produce the carbohydrates stored in the tubers.
Potatoes dedicate the initial stage almost entirely to vegetative growth before switching to tuber production. Sufficient nitrogen must be available early on to build the “photosynthetic factory” that supports the crop’s yield. If nitrogen is lacking, the plant develops a smaller canopy, limiting the size and number of potatoes produced. However, too much nitrogen early on encourages excessive vine growth and delays the initiation of tubers beneath the soil.
Blood Meal’s Specific Composition and Suitability
Blood meal is a potent source of organic nitrogen, typically boasting an NPK analysis of 12-0-0 or higher. The nitrogen is highly available because soil microbes rapidly break down the proteins into forms the plant roots can absorb. This rapid breakdown makes blood meal act more like a fast-release synthetic fertilizer than a traditional slow-release organic amendment, supplying an immediate boost that lasts for several weeks.
This quick-release characteristic makes blood meal an excellent match for the potato’s high nitrogen demand during early vegetative growth. Supplying this concentrated nitrogen helps the plant quickly establish the lush foliage needed for maximum carbohydrate production. Blood meal ensures the nutrient is available precisely when the potato plant is focused on building its above-ground structure. Gardeners can target this specific growth phase without adding excess phosphorus or potassium, which are needed more heavily later in the season.
Proper Application Techniques and Timing
The timing of blood meal application is more important for potatoes than the quantity, given the plant’s two-phase growth cycle. The primary application should occur at planting, mixing the product into the soil just before placing the seed pieces. This ensures nitrogen is available as the sprouts emerge and begin vegetative growth.
A general application rate is approximately 2 pounds of blood meal per 100 square feet, or 1 to 2 tablespoons per linear foot of row. Avoid direct contact between the concentrated powder and the potato seed piece or young stems, as this can cause fertilizer burn. After application, the blood meal should be thoroughly mixed into the top few inches of the soil and watered well to begin the microbial breakdown process.
A second, lighter application can be beneficial during the first hilling operation, typically when the plants are six to eight inches tall. This side-dressing provides a continued nitrogen supply to support the developing haulms. However, all nitrogen applications, including blood meal, should cease before the plant begins to flower or set tubers. Applying nitrogen past this point encourages continued leaf growth at the expense of tuber bulking, leading to smaller potatoes.
Managing Over-Fertilization and Pest Attraction
The concentrated nature of blood meal carries a risk of over-fertilization, which can be detrimental to the potato crop. Applying too much can lead to nitrogen burn, damaging the plant’s roots and foliage with an overly concentrated salt solution. The visible result is often scorching or yellowing on the edges of the leaves.
Excessive nitrogen encourages an imbalance in growth, causing the plant to produce heavy, lush vines while delaying or minimizing tuber initiation and bulking. This results in a small yield of potatoes despite a healthy-looking plant. Growers must transition to fertilizers higher in phosphorus and potassium once the plant begins to set tubers.
Another factor is the inherent smell of the dried blood, which can attract carnivores and scavengers such as dogs and raccoons. These animals may be drawn to the scent and dig up the freshly planted rows. Mixing the blood meal thoroughly into the soil, rather than leaving it on the surface, helps mitigate this attraction.