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Aloe vera plants are known for their ease of care in all areas, from watering to fertilizing. While they don’t need a nutrient boost often, aloe in containers benefits from occasional feeding once or twice per year.
Coffee grounds are somewhat controversial in the gardening world. Some gardeners swear by using them, and others strictly avoid them. So should spent coffee grounds be used as fertilizer or not?
If you haven’t fertilized your aloe plant in a while, you may wonder whether those used coffee grounds in the kitchen can act as a fertilizer for Aloe. We’re here to explain.
The Short Answer
Coffee grounds are not considered a suitable fertilizer for aloe vera. Although coffee grounds have some benefits for use on plants, there are far more downsides to their use specifically on aloe vera. It’s better to use a balanced, succulent-specific fertilizer applied at half strength.
The Long Answer
Using coffee grounds in the garden can be a controversial topic online. Some gardeners swear by it, while others claim it doesn’t provide the benefits people say it does. It can be hard to separate fact from fiction in these cases, especially when using spent coffee as a fertilizer.
Spent coffee is considered a sustainable and cost-effective soil amendment for several plants. This practice is so popular that coffee shops often give it away for free for use in the garden. My local coffee shop uses this system, and I frequently spot gardeners popping in with their garden buckets.
Coffee grounds contain trace amounts of nitrogen that can benefit plants when used as a fertilizer. Some proponents also say they can acidify the soil pH, however some research indicates that the change in pH is negligible.
Regardless, breaking them down in your compost pile first is preferred rather than adding them straight to the soil.
But there are also serious downsides to consider. The impact will depend on your chosen plant, so it’s important to thoroughly understand a species’ fertility and soil needs.
Fertilizer Needs
Aloe plants are known for their low-maintenance nature. They are native to harsh environments with high temperatures, where drought is common and the soil is gritty and nutrient-poor. These succulents clearly know how to handle themselves without much input from their owners. In fact, I’ve found that my aloes grow far better when I leave them alone rather than if I fuss over them too much.
Because these plants are so tough, they don’t need much fertilizing throughout the year, unlike other common plants described as heavy feeders. When grown in containers, they only need a nutrient boost around once per year – preferably applied in spring. Even this dose can be small, usually applied at half strength.
As they are accustomed to low-quality soils with little nutrients, there is a real risk of overfertilizing these plants. Overfertilizing can potentially lead to stunted growth and root damage that is difficult to resolve. It’s vital to avoid excess fertilizer by applying nutrients only when absolutely necessary.
Impact of Coffee on Soil
When you hear of the benefits of spent coffee for plants, it’s no wonder why many want to use them on aloe plants. Unfortunately, this practice has few negative side effects that far outweigh the cost-savings.
Soil Texture
When you add coffee grounds to an aloe vera pot as a fertilizer, you’re also altering the soil texture and drainage properties. As an essential foundation and influence on plant growth, drainage is vital to consider, especially for succulent plants like aloes.
Coffee grounds are often used as a soil amendment in homemade potting mixes to retain moisture. They absorb plenty of moisture and hold it around the roots, with similar properties to peat moss or coconut coir. While this is helpful for moisture-loving plants, it has the opposite effect on aloe plants, which love dry soil and are incredibly sensitive to root rot.
But that’s not the only downside. Even when left to dry out between waterings to limit the risk of root rot, they can become excessively dry too. In these cases, the material clumps together and compacts, becoming hydrophobic and repelling water that is added to the soil mixture.
Aloe plants prefer a gritty soil mix with large spaces between the particles to allow water to drain quickly. Coffee grounds negatively affect the soil texture, making them risky options to use as fertilizer.
Incorrect Nutrients
Studies of used coffee grounds show they contain around 2% nitrogen. This essential plant nutrient is the ‘N’ on the ‘NPK’ number you’ve likely seen on fertilizer packaging. As a macronutrient, nitrogen is essential in all-around plant health, including the health of your succulents.
However, nitrogen is not needed in substantial amounts for aloe vera to thrive. Most gardeners use a balanced fertilizer containing equal parts nitrogen, phosphorus, and potassium, or even a fertilizer high in phosphorus for the strongest possible growth.
Spent coffee also contains other trace nutrients, but not enough to consider it a balanced fertilizer. Since you won’t be fertilizing your aloe very often, it’s better to use holistic fertilizer with everything the plant needs in one go. Overusing coffee may eventually lead to a nutrient imbalance in the soil, negatively impacting overall growth.
Pest Problems
Another downside to consider is the effect on pests. Soil-borne pests like fungus gnats are attracted to the excess moisture created when this dense material is mixed into the soil. Thrips are another concern, along with various fungal diseases that can develop around the roots when the soil remains moist for long periods.
Aloes don’t often have trouble with pests, especially when grown indoors. The only issue I’ve ever encountered with mine is scale. Still, scales only occur on my aloes grown outdoors. To avoid increasing your chances of pest problems in these carefree plants, spent grounds are best avoided.
Changes in pH
In discussions around succulents and spent coffee, some suggest that coffee is not recommended because it can change the pH of the soil, making it more acidic. Because aloes generally prefer neutral to slightly alkaline soils, spent coffee is not ideal.
However, this doesn’t apply to the way most gardeners use their coffee – used. Fresh grounds are believed to impact soil pH, but used (brewed) grounds in small amounts commonly used as fertilizer have little effect on soil pH. The acidity leaches out from the coffee grounds to form that magical elixir we drink as a pick-me-up!
Although this downside doesn’t quite match up to the impacts of the others, it’s still vital to be aware of it, just in case you are considering using fresh coffee on your aloe plants.
What To Use Instead
Looking at the negative impacts, it’s clear to see why your spent grounds are best left on your compost pile rather than around your aloe plants. But that does leave the question of what you should fertilize them with instead.
As mentioned, aloe vera is best fertilized with a balanced slow-release fertilizer or a fertilizer with a higher phosphorus value. You can use a general houseplant fertilizer with equal NPK ratios or look for a fertilizer designed for use on succulents and cacti.
This fertilizer only needs to be applied around once a year in spring, preferably at half strength, to avoid issues with overfertilizing. Only apply what is recommended on the packaging, especially for these sensitive plants.
The Verdict
Coffee grounds are not considered a suitable fertilizer for aloe vera. But there are plenty of other fertilizing options that will give your aloe exactly what it needs to thrive.
