A complete guide to blood meal: Uses and precautions

You may have heard of blood meal being used as a fertilizer and recoiled back in horror! This dark red powder is pretty much how it sounds – ground animal blood! Putting blood on my plants? Never! Sounds like the stuff of nightmares!

Don’t be put off by it as blood meal is a really good fertilizer and an excellent source of nitrogen that plants love if used correctly. Nitrogen is needed by plants for nearly all processes so is crucial.

The nitrogen found in blood meal is vital as nitrogen is one of the building blocks for creating chlorophyll leading to healthy plant growth. If your plant is not getting enough nitrogen, it may not thrive and may even wither and die.

Blood Meal Fertilizer

What is Blood Meal?

Blood Meal is exactly how you would imagine, it is a plant fertilizer made up of animal blood –normally from cows, chickens, and pigs. The blood is a by product originating from abattoirs which is then heated at high temperatures to purify it. The blood is then ground down into a fine red/rust colored powder that is high in nitrogen and can be spread on the garden to feed your plants. I recommend using blood meal as a fertilizer in the spring as this is when your plant will need it most to form new shoots and foliage. It is recommended to use about a cup full of blood meal for every 20ft of soil but always follow the instructions on the packet. You may also have to reapply if your plants are looking low in nitrogen as it is easily washed away by the rain.

“Nitrogen may be found in various parts of the plant in different forms. There is nitrogen in the leaves, grain, plant tissue and roots of plants. Nitrogen may function as part of the plant structure or be involved in the life processes.” 

Karen DeFelice, former associate extension agronomist MU

Why use a high nitrogen fertilizer?

Simply put, plants love nitrogen! Nitrogen is vital for photosynthesis and for new growth. Nitrogen also gives plants their lush green color so if you notice your plant is looking yellow, pale, or stunted, it is probably nitrogen deficient. Fertilizers packed with nitrogen like blood meal can be used on plants, vegetables and on your lawn. There are some plants that naturally need a fertilizer high in nitrogen to thrive, but we will come to that a little later!

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What is nitrogen made of?

Nitrogen is an element found in almost everything on earth. It is in the air we breathe, the land we live on and the oceans that separate us. It is a naturally occurring element that is vital for plants to grow and survive – no plants – no life – so it’s a big deal!

Do all fertilizers contain nitrogen?

Whilst nitrogen is one of a plant’s basic needs, not all fertilizers will contain nitrogen.

You may have seen “NPK” on your fertilizer, this stands for Nitrogen (N), Phosphorous (P), and Potassium (K) and all three are vital to a plant’s health in different ways. Slow-release fertilizers will normally contain all three but along with nitrogen there are specific fertilizers only containing phosphorous and potassium, but why use them?

Phosphorous is needed for healthy root growth and germination so could be used for seedlings or newly planted gardens. It can also balance a soil that is already high in nitrogen as too much nitrogen can be a bad thing!

Potassium is also known as potash and is normally sold as tomato feed. Potassium encourages healthy plants and a greater abundance of flowers.  It is commonly used as a fertilizer when growing fruit or vegetables – as more flowers equals more fruit and veg!

Will blood meal burn plants?

If used too much Blood Meal will bur Although blood meal can be deemed as “natural” in the sense that it is not synthetic, it must be treated with care. If using blood meal on its own rather than a NPK fertilizer, always do a soil test before hand. Less is more! Too much blood meal and the roots will be burned, and your plant may experience an imbalance of nutrients and produce long straggly plants with very few flowers.

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3 other high nitrogen blood meal alternatives

Put off by putting dried animal blood on your plants, there are alternatives! I am not saying they are any more palatable but if you are looking for a fertilizer rich in nitrogen you could try the following:

  • Chicken manure – this usually comes in pellet form which acts as a slow-release fertilizer and has a rather funky smell. As with blood meal, use the correct dosage as too much can burn your plants.
  • Guano, not a caffeinated energy drink as I once thought, but bat droppings. Although high in nitrogen, guano also contains phosphorus and potassium making it a good allrounder. Guano also acts as a natural fungicide which is fantastic when gardening and improves the general health of the soil.
  • If animal derived fertilizers are not your thing, then you could also try alfalfa pellets. Alfalfa pellets are classed as a green manure, which is a fertilizer made up of highly nutritional foliage. Due to their fantastic vitamin and mineral content alfalfa pellets are often used as animal feed but can be used as a slow-release fertilizer also. As with guano, alfalfa not only has high concentrations of nitrogen but also contains phosphorous and potassium which can only be a good thing!

3 Types of plants/ use cases where high nitrogen is better

There are signs that your plants may be lacking in nitrogen. If your plants are discolored or pale, then they may be deficient in nitrogen.

The same can be said for plants that are growing poorly. Nitrogen is needed for cells to divide to create healthy and robust plants. If your plants are looking puny and unhealthy then they be lacking in nitrogen.

To confirm this, it is best to test the soil to confirm that you need to increase the amount of the nitrogen in the soil.

There are also plants that prefer a nitrogen rich soil. Soils containing a lot of nitrogen are usually acidic, and these conditions are loved by:

  • Hydrangeas
  • Azalea (Rhododendron)
  • Heathers

3 Types of plants/ use cases where low nitrogen is better

Conversely, you can have too much of a good thing and plants display a typical set of traits when there is too much nitrogen in the soil. As nitrogen is responsible for the production of healthy leaves and stems, you may notice that the whilst the overall plant looks very lush and healthy, there are no flowers or the roots are not forming well. Too much nitrogen means that the plant expends all of its energy on foliage leaving less nutrients for healthy root growth and fruit productions. For more on low nitrogen fertilizers check out our ultimate guide.

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Many plants do better in soils with a lower or normal level of nitrogen.  Many of these plants thrive in alkaline or neutral soils prefer a more general fertilizer where the levels of nitrogen are in moderation. These include:

  • Honeysuckle
  • Lilac Trees
  • Roses

Can Blood meal be used as a pest deterrent?

Wild rabbit
Wild rabbit

Blood meal can be used to deter pests but can also attract them too! Animals such as deer or rabbits that can quickly destroy a garden hate the smell of blood meal so is a fantastic deterrent for our leaf eating friends. However, the smell of blood can attract many a meat-eating animal such as foxes, raccoons, or bears so it’s best to know what kind of wildlife you have in your neighborhood!

What is the difference between bone meal and blood meal?

Blood meal and bone meal can sometimes be interchangeable but there are marked differences. Yes, they both come from animals but as I am sure you have guessed, blood meal is derived from animal blood and bone meal is crushed up animal bone!

Bone meal does not have high concentrations of nitrogen like blood meal but is a good source of phosphorous which is essential for root growth.  If you are worried that you have put too much blood meal on your garden, then you can also use bone meal to counteract this.

Final thoughts

Blood meal has been used as a fertilizer for a long time, in fact if you think about it, it was probably one of the first fertilizers made. You are recreating what nature has done for thousands of years!

It can be used on its own or as part of “blood, fish and bone” fertilizer which has a more balanced NPK. It is available pretty readily and is cost effective. I could even argue that it is a natural and organic as there is very little processing as it is simply dried and powdered animal blood.

Brock

Brock is the head gardener and editor-in-chief at Bigger Garden. Every year you can expect to see something new in his raised beds, from purple broccoli to cotton candy peppers.

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