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Do Boston Ferns Like Coffee Grounds? (Pros & Cons+How To Use)

Boston ferns are popular indoor plants that purify the air, have beautiful bright foliage, and are easy to maintain. Since coffee grounds are popularly used for fertilizing, you might be wondering if you can add coffee grounds to your Boston fern. Let’s find out.

Boston ferns will benefit greatly from coffee grounds if you use them correctly. Coffee grounds are rich in nitrogen which can boost the plant’s growth. Also, Boston ferns prefer acidic soil with a pH level of 6.0-6.5, so adding coffee grounds to the soil will not harm them. 

I will discuss how to use coffee grounds on your Boston ferns so that the plant can benefit from them. I will also talk about the mistakes to avoid while using it.

Boston fern light requirements

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Are coffee grounds good for Boston ferns?

Boston ferns, also known as sword ferns, grow best in low pH soil.

They are quite hardy by nature and prefer a pH of 6.0 to 6.5.

Coffee grounds are rich in Nitrogen which helps a plant capture sunlight and convert it into energy.

Coffee grounds also make the soil acidic, ideal for Boston ferns.

Boston ferns need a good amount of Nitrogen to grow and keep their lush green leaves intact.

As Boston ferns have bright green colored leaves, a good amount of nitrogen to preserve the color and keep it healthy.

Coffee grounds are readily available as coffee is a popular beverage in most households.

One should remember that overuse of coffee grounds will be deadly to the Boston ferns.

The correct amount of Nitrogen will help the soil medium become fertile and help Boston ferns thrive.

How often should I add coffee grounds to my Boston fern?

Although coffee grounds help keep Boston ferns healthy, you should not use them more than once a month.

Boston ferns require fertilizers made specifically to suit their needs, and coffee grounds alone cannot keep the plant healthy.

Keep in mind to check your fern regularly to see how it reacts to the introduction of coffee grounds into its soil.

If you use good quality soil that is also well balanced, it will usually have a good amount of Nitrogen.

So please be sure to check the soil before adding coffee grounds. 

Also read: Should I Fertilize My Boston Fern? (Ideal Fertilizer+When & How Much)

Benefits of using coffee grounds

Let us go through the advantages of using coffee grounds on Boston fern:

Improves soil structure

Used coffee grounds are inexpensive organic additives to improve soil quality.

Adding coffee grounds into the soil can help the Boston ferns regularly.

Coffee grounds are small particles, so there is a chance of them becoming compact and causing waterlogging.

So, remember to mix it well with the soil to prevent such mistakes.

It keeps the soil aerated.

Mixing coffee grounds properly with the soil helps to aerate it.

Aeration will help reduce the compaction of the soil, allowing it to oxidize so the plant’s roots will be able to absorb appropriate nutrients.

Improves water retention of soil

Any form of organic matter like coffee grounds will help the soil retain an optimum moisture level.

This will prevent the soil from becoming too dry during hot summers, improving the overall health of your Boston fern.

Boosts Nitrogen in compost

Coffee grounds have a reasonable amount of Nitrogen, which helps break down the compost and add high amounts of essential nutrients.

Nitrogen also helps maintain the lush green color of Boston ferns’ leaves.

So, using compost-containing coffee grounds for your Boston fern will promote foliage health.



Keeps away slugs and snails

Slugs and snails feast upon the leaves of the plants, making them look ugly.

These pests can cause a serious decline in plant health.

It is believed that the strong taste and smell of coffee can keep them away from your plant.

Also, the grainy texture of coffee grounds acts as a physical barrier preventing the slugs and snails from crossing it.

May repel cats

Cats usually love to use the indoor garden area as a litter box.

They can defecate in plant pots and the soil, mulch, or gravel, causing much nuisance.

Cats are quite moody creatures.

They can uproot your favorite plants and destroy them as well.

To fight this issue, you can use small heaps of coffee grounds around your garden or mix them with the topsoil of your Boston fern.

It is a popular remedy to keep cats away from your plants.

Make sure that you do not form a thick layer of coffee on the topsoil, cutting off air from reaching plant roots.

Boston fern new growth

Reduction of waste and chemical usage

Coffee grounds will get wasted if not recycled and end up in the trash can and eventually in a landfill.

Any object that may be recycled or reused has a good impact on the world and the environment.

Coffee grinds are an organic resource that can be considered an environmentally friendly option.

Using coffee grounds as an alternative fertilizer instead of adding synthetic fertilizer every time:

  • You reduce the number of chemicals released into the environment.
  • Contribute to a more organic and natural landscape
  • Conserve local waterways and the ecosystem’s delicate balance.

Disadvantages of using coffee grounds

If you don’t use coffee grounds correctly, it can lead to the following problems.

May form a thick barrier over the soil.

Coffee grounds are made up of very fine particles that can quickly become compact and form a solid barrier when they dry out. 

If you use neat coffee grounds as a mulch on topsoil, you’ll have a texture comparable to clay soil, which is awful for your Boston fern.

Your plants will die of thirst if you place a physical barrier over the top of your soil impervious to water.

It can cause harm to dogs if ingested.

Avoid placing coffee grounds around your plants if you have a pet dog.

Coffee grounds can be hazardous to dogs if consumed.

Affect seedling growth

Caffeine can prevent seedlings from developing, which is why coffee plants thrive.

Caffeine inhibits surrounding plants from growing.

As a result, if you’re cultivating young plants of Boston ferns, you should keep coffee grinds away from them.

They can harm the plant’s roots, causing it to die before it even gets a chance to grow.

May suppress root growth

Caffeine can inhibit the plant’s root growth and lead it to become stunted. 

Although coffee grounds are less likely to hurt adult plants than seedlings, it’s still worth thinking about if you don’t want to compromise the health of your favorite Boston fern.

Can cause fungal growth

If you apply a heavy layer of coffee grounds as a mulch, fungal growth may appear.

Fungal growth will eventually cause various problems for the fern if not checked immediately. 

Can destroy good bacteria in soil

Antibacterial properties are present in coffee.

While this is considered a benefit in general, it can pose major issues regarding soil health.

Many different varieties of beneficial bacteria keep pests and illnesses away from your plant in the soil.

If you use coffee grounds in excess, you will kill all of the beneficial bacteria, making the soil prone to pests and illness in the future. 

The loss of healthy bacteria will also harm the soil’s natural biodiversity, which can cause several issues for earthworms and other organisms living there.

Excess acidity

Always make sure to check the pH of the soil before adding coffee grounds to it.

As mentioned earlier, using too many coffee grounds frequently can disrupt the pH balance of the soil.

Even though Boston ferns thrive in acidic soil, the plant health will suffer if it becomes too acidic.

What is the best way of using coffee grounds on Boston ferns?

Composting with Coffee Grounds

The best way to add coffee grounds is to add them to the compost.

It’s easy: simply toss your leftover coffee grounds into your compost bin and use the compost whenever it’s ready.

In addition to providing nutrition, the Nitrogen in the coffee grounds helps break down the other components in the compost, resulting in a rich, well-mixed final product.

However, be sure that coffee doesn’t account for more than 20% of your overall compost.

Levels higher than 30% might be harmful.

As liquid fertilizer

Coffee grounds contain roughly 2% Nitrogen, which is the most important nutrient for Boston ferns’ healthy, green foliage.

  • To create a liquid fertilizer out of your coffee grounds, take a container and add some water to it.
  • Now, put it on the gas and turn it on.
  • Let it simmer.
  • Turn the gas off and let the water cool down.
  • Now, add coffee grounds to the water.
  • Leave this aside for 1-2 weeks and stir it after every few days.
  • Once you notice that the coffee grounds have broken down, strain it and use it on your Boston fern.

Mix with mulch

Mulching with coffee grounds is a simple way to provide your Boston fern with the benefits of coffee grounds.

Simply cover the top of your fern’s soil with a quarter-inch layer of grinds mixed with other organic mulching materials like pine bark or leaf mold.

Make sure the coffee isn’t in clumps and is equally spread.

The nutrients will slowly sink into the compost below, while the coffee will keep pests, illnesses, and weeds at bay.

When using coffee grounds as a mulch, make sure the layer is not too thick, as the small particles can form an impenetrable barrier that prevents air and water from flowing through, depriving the fern of these essentials.

As Compost Tea

If you don’t have a compost container, making compost tea is a simple and practical way to use coffee grounds on your ferns.

Fill a large glass jar halfway with used coffee grounds, then top it over with water.

Keep the jar in a warm, out-of-direct sunlight location for several weeks or longer.

You can strain the tea or not; you can even make more tea with the same grounds by adding fresh ground.

When watering your fern, add one cup of every half gallon of water to use your coffee compost tea.

Can I water my Boston fern with leftover coffee?

In short, yes, you can water Boston ferns with leftover coffee but not too often.

But, follow the tips given below to get the best results:

  • Use diluted coffee on the ferns.
  • Don’t use the diluted coffee fertilizer every time you water. 
  • If the soil becomes excessively acidic, ferns can grow sick or die. 
  • Yellowing leaves could indicate too much acid in the soil, in which case you should stop watering the plants with coffee and repot it in fresh potting mix.
  • Do not pour a hot cup of coffee on your fern as it will burn it badly.
  • Make sure to check the soil acidity level before adding the leftover coffee.

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Final words

Coffee grounds can benefit Boston ferns if used carefully, as they prefer acidic soil.

Here are 3 points to keep in mind while using it:

  • Coffee grounds used in compost will have less chance of harming your plants and soil. In the compost, never use more than 20% coffee!
  • If you’re going to mulch with coffee grounds, mix them with other materials and keep the layer below a quarter-inch thick.
  • You should never use coffee grounds as liquid fertilizer or compost tea on seedlings or young plants.

Reference: University of FloridaThe University of Arkansas DivisionTexas A&M University SystemThe University of GeorgiaUniversity of New HampshireWikipediaThe Royal Horticultural Society.