I’ve talked a lot about using coffee grounds in the garden and have also written a few articles on different plants that may or may not like coffee grounds such as roses, tomato plants and lavender. In this article, I want to focus on begonias and discuss whether you should use coffee grounds on them or not.
As begonias are generally acid-loving plants, if you grow these out in your garden, they could benefit from the use of coffee grounds. As organic matter, coffee grounds are reasonably acidic and will alter the pH of the soil slowly over time.
So, if you’ve tested the soil and it’s neutral to alkaline, then scattering a small amount of coffee grounds around the base of your plants can be beneficial. But use spent grounds and not fresh coffee grounds and remember that soil amendment does take time.
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It’s also said that coffee grounds can be good at keeping slugs and snails away from your plants because they don’t like the strong odor. So, you could use them as a barrier around young begonias to protect the plants from these pests.
How To Use Coffee Grounds On Begonias In The Garden
It’s important to note that we’re talking about begonias that you have growing outside in your garden. We’ll discuss indoor plants a little later.
When applying coffee grounds to any plants, like begonias, in your garden, make sure that you don’t overdo it. Essentially, you just want to sprinkle a very thin layer of the used grounds on the garden soil around the base of your plants.
If you spread too many grounds or you just dump a pile of your used grounds, the grounds tend to form an impenetrable layer once they dry out. So, make sure that you use dry leftover coffee grounds and just sprinkle them lightly.
Then, water the soil so that the grounds are washed into the soil and can make their way down to where the plant roots are. This is when they’ll provide the best benefits to your plants.
How To Use Coffee Grounds To Create A Pest Barrier
On the other hand, if you want to use the coffee grounds to create a pest barrier around your begonias, you want to use a totally different method.
For this, you want to spread the grounds in a ring around the base of the plant. Keep this barrier a little distance away from the main stem. It doesn’t matter whether you use wet or dry grounds for this because we want the ground to become a barrier.
You can even mound the grounds up a little but I would suggest that you keep them at least 30 cm (12 inches) away from the stems of your plants. As the grounds dry and create a crust, it will be difficult for water to penetrate into the soil.
Keeping the grounds at this distance means that the soil around your begonias will still allow moisture to penetrate to keep your plants well hydrated.
But, pests such as snails and slugs will not want to crawl over the coffee grounds to get at your delicate plants.
Should You Fertilise Your Begonias With Coffee Grounds?
While coffee grounds do contain a decent amount of nutrients, especially nitrogen, they shouldn’t be used as a complete fertiliser for your begonias. Begonias need a relatively balanced fertiliser for good plant growth and also to promote flowering.
I’ve talked a lot about fertilisers in other articles, so I’ll just cover the basics here. If you want more in-depth information about the best fertilizer for begonia, you might want to check out my article here.
For plenty of good leaf growth, your begonias will need nitrogen. To promote strong root growth, they need phosphorus. But, when you want to promote flowering, you’ll need a decent all-round fertiliser that contains plenty of potassium.
So, you want to look for a fertiliser that has all three of these major nutrients in fairly equal amounts. Usually, fertilisers that are labelled for use on other flowering plants such as roses or azaleas, will work well for begonias.
Expert tip: If your begonias are producing lots of growth but not many flowers, they need more potassium. You might want to check out my article on ways to use banana peels in the garden for some great tips.
Should You Use Coffee Grounds On A Potted Begonia Plant?
In all honesty, I would not use coffee grounds on any potted plants, even those that like acidic soil such as tuberous begonias. The main reason being that the grounds will form a crust when they dry and this can stop the water from penetrating into the potting soil.
Another important thing to remember here is that moist coffee grounds can actually promote fungal growth. This is definitely something that you want to avoid introducing into your houseplants.
Some people suggest using cold brewed coffee water that’s been diluted to fertilise indoor plants such as begonias. But, I don’t think that the coffee has enough balanced nutrition to be of benefit.
If you want to create your own liquid organic fertilizer for your begonias, you’re better off getting a Bokashi bin and using the liquid from this. Or, you could consider getting a worm bin and using the worm tea as a natural fertilizer for your begonias.
Personally, I like to use a nice balanced liquid fertilizer on my houseplants for the best results. Or, for ease of application, I tend to stick with slow-release fertiliser pellets that I only have to replenish every six months or so.
So, while you can safely use a small amount of coffee grinds on your garden plants, I would suggest that you don’t use them on your potted plants. It’s far better to add the coffee grounds to your compost heap. You can also add the grounds to your worm bin if you have one. The worms will love them.
You can then use the compost to mix with your potting soil to create a lovely nutrient-rich growing medium for your begonias and other indoor plants.
Did You Know That Coffee Grounds Are Amazing For Your Compost Pile?
I’ve been adding used coffee grounds to my compost bins for a few years now and have had amazing results. Because I have a coffee machine in my house and grind my own coffee beans, I have used grounds on a daily basis. I just tip these into my indoor compost collection bin in my kitchen and then empty this into my outdoor compost bins regularly.
What I’ve found is that my compost is now absolutely full of earthworms. It seems that they really love the coffee grounds and are using my compost bin to breed in. So, when I collect the compost, it’s usually full of earthworms that end up in my garden beds.
This is a wonderful way to improve the health of the soil, especially when I use these garden beds to grow vegetables. Having all these worms in my garden helps to improve the soil structure and the worm castings help to give my plants plenty of essential nutrients. So much so, that I rarely have to add any supplementary fertilisers.
That’s why I really like to encourage all coffee lovers who also like to garden to invest in a compost bin and add the coffee grounds along with any vegetable scraps, lawn cuttings and dry leaves. It’s the best way to create your own fertiliser and it’s free!
Even people who live in an apartment and don’t have an outdoor space can benefit from making their own compost. In fact, I’ve written an article that describes exactly how to do this.
Frequently Asked Questions
You can safely use a small amount of coffee grounds on most garden plants that prefer an acidic soil pH. These include azaleas, hydrangeas, impatiens, blueberries and begonias.
You should avoid using coffee grounds on any garden plants that prefer a more alkaline soil pH level. This includes plants like geraniums, Chinese mustard and asparagus fern.
Coffee grounds should only be sprinkled on the soil in your garden sparingly. And, you should only add them every two or three weeks as long as you only sprinkle a very thin layer on the soil.
Yes, you can just sprinkle a very thin layer of coffee grounds on top of the soil. Make sure that the layer is not too thick because the grounds can become impenetrable to water once they dry.
As most ferns prefer more alkaline soil, adding coffee grounds would be detrimental to the health of these plants.
As coffee grounds are acidic, they can alter the acidity of the soil over time which will not benefit plants who don’t like acidic soil. Also, as the grounds break down, they can tie up the available nitrogen in the soil which can inhibit nutrient take up by plant roots. Plus, the caffeine present in coffee grounds can suppress the germination of some seeds and suppress the growth of some plants.
Final Thoughts
If you’ve ever asked the question – “Do begonias like coffee grounds?”, you now have the answer. While coffee grounds can be beneficial to any begonias that you have growing out in your garden, they should be used sparingly and not added to the soil too often. They will provide your begonias with valuable nutrients once they break down into the soil.
You should remember to avoid excessive use of coffee grounds and only sprinkle them in a very thin layer around the base of the plants but keep them a little distance from the main stem. You can also use them to create a pest barrier against snails and slugs.
But, the best way I know to recycle my used coffee grounds is to add them into my compost. This is a great way to benefit the soil for both now and into the future.
