Many gardeners prefer to feed their flowers naturally, using organic fertilizers that don’t harm the environment or the organisms within it. Blood meal is an organic fertilizer option that offers many benefits to some types of flowers. However, if it is not used properly and with caution, blood meal can burn or kill your flowers instead of helping them.
Blood meal is a by-product of the slaughterhouse industry that is available at most feed stores and nurseries. It is one of the highest, natural sources of nitrogen for plants. When animals are slaughtered, the blood is dried, ground into a powder, and then flash-frozen. The result is a reddish-brown powder that is effective as a nitrogen source for flowers and other plants. Blood meal has a nitrogen-phosphorous-potassium ratio of 12-0-0. This means that it is composed of 12 percent nitrogen, or for every 100 pounds of blood meal, you’re getting 12 pounds of nitrogen.
Pros and Cons
As a source of nitrogen for your flowers, blood meal breaks down more quickly than other types of organic fertilizers, releasing nitrogen over a period of one to four months. Because it is a high-nitrogen fertilizer, blood meal does not promote flowering but instead encourages green, leafy growth. Excess nitrogen can inhibit blooming because the plant’s energy is diverted toward the lush, green growth of foliage instead. Blood meal also has no phosphorous or potassium, which isn’t ideal for many perennials. These need a balanced fertilizer containing nitrogen, phosphorous and potassium. However, annuals typically respond well to a high-nitrogen fertilizer as long as you’re careful not to apply too much because burning of flowers and foliage can occur due to the ammonia content. Blood meal is also toxic to animals.
Blood meal is ideal as a side-dressing to give your flowers additional nitrogen during the growing season. For cool-season annuals, such as pansies (Viola wittrockiana), which are typically hardy to U.S. Department of Agriculture plant hardiness zones 3 through 8, apply blood meal early in the growing season when soil is cool. For warm-season annuals, such as impatiens (Impatiens spp.), which are hardy in USDA zones 10 and 11, apply blood meal about four to six weeks after transplanting outdoors and if rainy weather or frequent irrigation has occurred. For annuals that grow throughout the summer, apply an additional side-dressing four to six weeks after the first to stimulate late-summer growth. When applying blood meal to roses (Rosa spp.), which vary in hardiness depending on the species, apply bone meal to the soil prior to planting. For established roses, apply bone meal as a side dressing prior to flowering, and repeat application in three-month intervals during the growing season.
To apply blood meal to flower beds, scatter 2 pounds of blood meal for every 100 square feet of soil along either side of each row of flowers. Water the soil thoroughly after application. When applying to groupings of annuals, apply 1 pound of blood meal for every 25 plants as a side dressing to encourage larger blooms and greener foliage. You can also apply blood meal prior to planting. Till in 5 to 10 pounds of blood meal for every 100 square feet of soil and then water thoroughly. If you’re applying blood meal to roses, use 1 pound per 100 square feet of soil. If any blood meal touches flowers or foliage, rinse with water immediately to prevent burning.