The use of coffee grounds in backyard gardens has become an increasingly popular trend of late. Coffee grounds are rumored to have multiple benefits for plants, but is there any merit to this claim? Is it even safe to use coffee grounds in your garden?
Coffee grounds are good for staghorn ferns in moderation. They make for good slow-release fertilizers, can help raise acidity levels, and may even have anti-microbial benefits to boot.
The claim that coffee grounds are good for plants is the subject of frequent skepincticism. Let’s put an end to this debate once and for all by analyzing facts and reviewing evidence.
Coffee Grounds Are Good Organic Fertilizers
Even if you’re a beginner gardener, chances are you’re familiar with the big three nutrients all plants need to grow – nitrogen, phosphorus, and potassium – NPK.
Coffee grounds consist of 1.5 to 2% nitrogen. This may seem meager, and it sure is compared to traditional all-purpose fertilizers, which typically boast 10 to 20% nitrogen by volume.
While you can’t use coffee grounds as a substitute for regular fertilizer, you can use them to complement a pre-existing fertilization plan. Every little bit counts, after all.
Coffee grounds are slow-release fertilizers, which means they release their nutrient content over a larger period of time. This is beneficial because too much nutrient density in the soil at a time can harm plant health.
Also, coffee grounds have several other important nutrients, such as magnesium, calcium, and potassium. Like nitrogen, these nutrients are also present in coffee grounds in marginal quantities.
So what does that mean for the humble coffee bean?
Coffee grounds clearly lose to traditional fertilizers if nutrient addition is your only goal. When it comes to staghorn ferns, they typically need to be fertilized monthly during their growing period. This growing period lasts through the better part of spring and summer.
If you’re a casual gardener who doesn’t use traditional fertilizer or just someone who prefers to make their own fertilizer, coffee grounds are perfect for you. We’ll discuss how you can incorporate coffee grounds into your fertilizer mix to make something entirely homemade but not lacking in nutrients.
Coffee grounds are also a great complement to banana peels – one of the more common organic fertilizers you’ll see being used by casual gardeners.
While they do contain considerable quantities of potassium and phosphorus, banana peels are lacking in nitrogen. Coffee grounds can compensate for this shortcoming and give you a healthy all-around diet to feed your staghorn ferns.
Also worth mentioning here is the fact that coffee grounds make a great organic addition to the soil. Staghorn ferns thrive when there’s a high proportion of organic matter in their potting mix, making coffee beans all the more beneficial for this plant.
Organic matter is better at water retention than regular soil, so your staghorn fern won’t get thirsty as often – a small side benefit.
They Also Help Raise Soil Acidity
Coffee grounds are acidic in nature, so when they decompose, they increase soil acidity. Depending on your situation, this can be beneficial or detrimental.
Staghorn ferns prefer slightly acidic conditions, as do many other plants. Slightly acidic (think 6.5 to 7.0 pH) is generally the sweet spot for most household varieties commonly grown today.
Using coffee grounds in moderate amounts is fine if you have neutral or alkaline soil. It’ll help make the soil slightly more acidic. However, if your soil is already acidic, it may be best to hold off on using coffee grounds.
How do you find out how acidic or basic your soil is? You’ll need to use a soil testing kit. Either that or you can send a sample of your soil to your local agriculture department and have them test it for you.
There’s one thing I should clear up. The degree to which coffee grounds make a difference in soil pH is often exaggerated.
In fact, one of the most common arguments against the use of coffee grounds is the irrational fear that they kill plants by making the soil too acidic. There’s little merit to that claim.
The thing is, much of the acidity present in coffee beans is eliminated when they’re brewed and turned into coffee grounds. Coffee grounds actually aren’t that acidic at all. They’re very close to being neutral.
So unless you’re adding absurd quantities of coffee grounds to your soil, you likely won’t see a dramatic change in pH.
Used Grounds May Have Antimicrobial Benefits
Coffee grounds have been tested for anti-microbial properties. Unfortunately, the evidence seems to be rather mixed. Some reports show that coffee grounds harbor anti-fungal properties and can discourage the growth of fungus in the soil.
Soil-based fungus is a notorious threat to plants. It’s hard to treat (because it’s in the soil), and it eats away at the roots, often causing irreparable damage.
If anti-microbial capabilities do indeed exist in coffee grounds, then their use would be extremely beneficial. However, the studies providing the evidence were conducted under controlled circumstances. It’s likely the case that real-life results differ vastly.
Fortunately, staghorn ferns aren’t usually plagued by soil-based fungi. Therefore, whether or not coffee grounds combat fungi is not of much consequence in this case.
Moderation Is Key
We’ve established that coffee grounds do benefit staghorn ferns. It’s just that their benefits are marginal and not to be overestimated.
Now, it’s important to discuss the downside of using coffee grounds. Unfortunately, it seems that coffee grounds have compounds that are inherently damaging to plant health when they’re in large quantities.
I mentioned earlier that coffee grounds can hurt plants because of their acidity. That’s true. Additionally, if you use too many coffee grounds, the harmful compounds within can cause minor damage and slow down growth.
This damage is short-lived and easily remedied by simply not adding more coffee grounds to the soil. It’s nothing to be too concerned about.
Using coffee grounds on a seed, seedling, cutting, or baby staghorn fern is not advisable. You will likely do more harm than good. Use coffee grounds as fertilizer only for fully grown, adult staghorn ferns.
This applies to other plants as well. Seedlings of any kind are at risk of incurring damage if left exposed to coffee grounds. Of course, it doesn’t help that once you’ve added coffee grounds to the soil, removing them is not at all practical.
Ways To Safely Treat Your Staghorn Ferns to Coffee
Now that we know all about coffee grounds, let’s look at creative ways to use them in the garden and for our staghorn ferns, in particular:
Add Leftover Grounds to Compost
This is probably the best way to use your leftover coffee grounds. Making your own compost at home is a rewarding process. It’s not as difficult as you might think, either. All you have to do is collect decaying organic matter in a compost bin.
This includes items such as:
- Dead leaves
- Leftover food
- Rotten fruits and vegetables
- Grass
- Used tea bags
The list of things you can add to your compost bin is quite extensive.
Use up to 20% of coffee grounds by volume in your compost. If you go any higher, you risk running into the adverse effects discussed above.
You can then use this compost to fertilize your staghorn ferns, or any other plant, for that matter. Compost is versatile and has several beneficial applications.
Adding coffee grounds to compost gives you a decent source of slow-release nitrogen while also diluting the coffee grounds such that you won’t suffer the negative side effects that accompany overuse.
Use the Grounds to Mulch
Mulch is another valuable asset in your homemade gardening arsenal you can use to help your staghorn ferns thrive.
It’s a layer of organic matter, much like compost, that you can spread over your staghorn fern’s roots to help preserve moisture and provide insulation against extreme temperatures.
Since coffee grounds have water-retaining properties due to them being organic matter, you can mix them in with mulch. Apply only a thin layer of coffee grounds, though, as too much can result in waterlogged or compacted soil.
Mix Them Into Your Potting Soil
Adding coffee grounds to your potting mix before planting the staghorn fern is a great way to kick off your fern’s journey with some organic, slow-release fertilizer.
Doing so will also allow more air into the soil – the presence of air pockets in the soil is necessary for healthy roots.
Final Thoughts
So, what’s the final verdict?
Coffee grounds are simple, easy-to-use organic fertilizers that can provide your staghorn ferns with slow-release nutrients. They also increase soil acidity slightly, and staghorn ferns love slightly acidic soil.
Coffee grounds may also have antifungal properties, but that doesn’t make much of a difference in this case because staghorn ferns aren’t particularly susceptible to soil-based fungus, to begin with.
The important thing to remember when using coffee grounds is not to go overboard. Use minimal quantities and get a modest boost to your fern’s health.
