Can You Grow Microgreens in Coffee Grounds?

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Are you tired of throwing away all your old coffee grounds? With so many devoted coffee drinkers in today’s busy world, all the used coffee grounds could surely be more than just waste. If you’ve been considering ways to reuse old coffee grounds, you will be happy to know that coffee grounds have many outside uses besides being your morning boost – one of which is fostering the growth of microgreens!

Can you grow microgreens in coffee grounds? You can grow microgreens with coffee grounds, but you will not likely have a positive growing experience if you only rely on coffee grounds.  While coffee grounds offer nutrients to the soil, they are quite acidic and can damage plant roots if used alone to grow your microgreens.   

This article will explain the benefits of using coffee grounds to grow microgreens. You will also learn how you can grow microgreens using coffee grounds as well as other tips and tricks as you begin your growing adventure.

Using Coffee Grounds as Soil

When you look at coffee grounds, you can see their resemblance to soil.  While both coffee grounds and soil contain nutrients that can help plants thrive, it is crucial to know the nutrient content is vastly different between the two. Because of this, microgreens cannot thrive in a growing environment made entirely from coffee grounds. 

Coffee grounds are acidic and work well for growing fungi such as mushrooms that easily grow in fertilizer. Since mushrooms and other fungi depend on acidity for ample growth, coffee grounds would be ideal for them.  

Microgreens, on the other hand, are a bit more delicate and require a balanced soil compound to grow effectively and efficiently.  When growing microgreens, you won’t likely experience success with only coffee grounds, but a mixture of soil and coffee grounds will likely be effective.

What Nutrients are in Coffee Grounds?

Most people know that coffee contains caffeine but are unaware there is actual nutritional value in the coffee grounds themselves.  Registered dietician, Kayla McDonell explains in her article 16 Creative Ways to Use Old Coffee Grounds, that coffee grounds contain several vital nutrients for plant growth, including:

  • Nitrogen 
  • Calcium 
  • Potassium 
  • Iron 
  • Phosphorus 
  • Magnesium 
  • Chromium 

Each of these nutrients is critical to the healthy growth of plants, including microgreens. 

If you decide to use coffee grounds to grow your microgreens, you need to make sure the grounds are mixed into the soil appropriately. To use coffee grounds you should ensure to use a ratio of up to 35% coffee grounds to soil. Make sure not to overuse it.

If your soil is high in nitrogen, you can add less coffee grounds. Avoid spreading the coffee grounds directly around the seeds as that may impact the germination.

Types of Coffee Grounds to Use

Now that you know how to use coffee grounds to grow microgreens properly, you may be wondering if certain grounds work better than others.  The good news is that you can use both regular and decaffeinated coffee grounds; however, Dianna Morris of the Utica Observer-Dispatch gives some cautionary advice about decaf coffee grounds in her article Coffee Grounds Can Perk Up Your Garden’s Soil.

If you are using decaffeinated coffee grounds, Morris warns that you should be aware of the process used to remove the caffeine from the coffee beans. Typically, chemical solvents are used to remove the caffeine, which means there may be traces of solvent left on the grounds.  The presence of this solvent may derail your attempt at organically growing microgreens. 

Do the Microgreens Taste Like Coffee?

Coffee has a distinct odor and taste, so you may wonder if it will impact the taste of the microgreens. While coffee grounds may impact the growth rate and color of your plants, you can rest assured that it will not impact their flavor! 

How Do I Store the Coffee Grounds?

Before you start tossing your coffee grounds into a container for future use, you need to be aware of how quickly mold can grow on them.  Fungi flourish in highly acidic environments, and this includes mold.  If you haphazardly attempt to store used coffee grounds, you will end up with a container full of mold and unusable coffee grounds. 

Follow these steps to store your used coffee grounds correctly:

  1. Remove the coffee grounds from the filter of your coffee maker.
  2. Place the grounds into an airtight container (there is no need to dry them).
  3. Place the container into a refrigerator.

You can generally use any container you have that has an airtight lid so that air does not get in. If air reaches the coffee grounds for an extended period (longer than it takes you to add new grounds each day), mold can begin to grow on your grounds. If you are unsure about the airtightness of the containers you have available, you may want to purchase a specific container.  

Here are some excellent options for storing your coffee grounds:

It is imperative that you put the grounds into the refrigerator immediately after placing them into the container.  If they are left at room temperature, mold spores will begin to grow, and the coffee grounds will be rendered useless. 

Can You Only Use Soil with Coffee Grounds?

You may be wondering if you can only mix coffee grounds with soil to grow microgreens successfully. You must remember the reason coffee grounds are being mixed with soil is to lower the acidity of the coffee grounds, which can damage the roots of the plants. 

If you mix coffee grounds with anything other than soil, you run the risk of damaging the sensitive roots of the microgreens and can lessen your chances of having a bountiful crop. 

Cautions with Using Coffee Grounds 

Everything you have read to this point explains the positives of using coffee grounds to help grow microgreens; however, there are some things you need to be aware of aside from the proper storage and mixing of the grounds.  

Some other important information about using coffee grounds to help grow your microgreens includes:

  • You may be inclined to sprinkle grounds over the top of the soil.  It is not recommended to do this. You will notice that coffee grounds clump together when they are wet. If you sprinkle grounds on the top of the soil, you are potentially creating a barrier that water won’t be able to penetrate. 
  • Make sure the ratio of soil to coffee grounds is correct.  If the ratio is off, you run the risk of burning the roots of the plant.  This is of great concern when dealing with microgreens because you don’t remove the roots, so the root system must stay healthy. 
  • If you are striving to grow organic microgreens, make sure you know where the coffee is sourced from or how the caffeine has been removed to ensure you are using the purest form of coffee grounds possible. 

Final Thoughts

As you can see, coffee grounds can provide a high-quality growing environment for your microgreens if you use them correctly.  To do so, you must understand the best way to use coffee grounds. Because some plants handle acidity better than others, you may need to experiment a bit or research the best conditions for the microgreens you are hoping to grow. With a bit of time and patience, you will likely have a microgreen garden that will produce an abundant supply for you to enjoy year-round. 

Microgreens Corner
Microgreens Corner
We are Janette & Jesper, and we love microgreens.

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