We have a fiddle leaf fig as well as a fig tree and we’re always looking at ways to naturally provide them with fertilizer. While compost is always a good option, I wanted to know if coffee grounds specifically were good for them. So, I did some more research to find out. Here’s what I found.
Used coffee grounds are good for fig plants since they add nitrogen and some acidity, which figs prefer. However, there are some concerns about the leftover caffeine in the coffee grounds. Caffeine is a natural pesticide, so some worry about it killing beneficial insects and soil bacteria.
So, while coffee grounds are normally good to give to fig plants, are there any downsides, and how many coffee grounds should you use? Let’s take a further look.
How Do Coffee Grounds Help Fig Plants?
Coffee grounds contain a good amount of nitrogen, phosphorus, magnesium, and copper, all of which are important to maintain a healthy fig plant. They also increase the acidity of the soil, which is helpful for fig plants as they prefer more acidic soil with a pH of 6.0-6.5.
Like most plants, figs rely on three primary nutrients to grow: nitrogen, phosphorus, and potassium (abbreviated as NPK). Luckily, coffee grounds provide all three of these nutrients, along with other secondary nutrients such as calcium, magnesium, copper, iron, boron, and zinc.
Coffee grounds are also slightly acidic with a pH of 5.5-6.8, which is pretty much perfect for fig plants since they prefer a soil pH of 6.0-6.5. However, used coffee grounds generally have less acidity than fresh grounds due to the process of brewing. Used coffee grounds generally have a pH closer to 6.8, which is still great for fig plants.
When you add any amendments to the soil, it’s always a good idea to check the pH. After all, if the pH falls outside of the preferred range of the plant, the plant will be unable to absorb the nutrients from the soil.
To help with this, you can use either a pH strip or a pH meter. I personally prefer using a pH meter since they’re affordable and easy to use. To see which pH meter I use on my plants, check out my recommended tools page.
Will Coffee Grounds Hurt Fig Plants?
Some say that coffee grounds contain too much acidity and caffeine to be used on the soil. But does this hold any truth?
Caffeine is a natural defense mechanism made by plants to repel insects. This makes it a naturally occurring insecticide. Generally, insecticides can cause more harm than good since they also kill pollinating insects and beneficial life in the soil. However, the science is mixed on the caffeine left in coffee grounds.
As shown in the section above, due to brewing, used coffee grounds have much less acidity than fresh grounds. Because of this, it would be fair to assume used coffee grounds also have much less caffeine than fresh.
However, some sources mention used coffee grounds can still be harmful to plant and soil life.
So, to stay on the safe side, the best solution here would be to compost your coffee grounds and let the caffeine and acidity break down. After some time in the compost pile, the nutrients should be the only things remaining from the coffee grounds.
How To Apply Coffee Grounds as a Fig Plant Fertilizer
If you have a handful of coffee grounds, you can apply it directly onto your plant’s soil. But if you have a daily pot of coffee, generally more than 1 cup, consider composting it first to decrease the caffeine. Usually, it takes about 2-3 months for the coffee grounds to decompose and become usable by the plant.
Depending on how many coffee grounds you have, and what you prefer, there are a few ways you can use coffee grounds as a fig plant fertilizer:
- Apply it directly
- Mix it with mulch
- Compost it
Generally, you can apply a small and infrequent amount of coffee grounds directly to the top of the plant’s soil (just make sure to keep them at least 3 inches away from the plant’s trunk).
However, if you have more than the suggested amounts of coffee grounds above, consider either mixing them with mulch or composting them before applying them to your fig plants.
For example, some good mulches to use for fig plants are straw, bark, and leaves. Simply mix the mulch and coffee grounds together and apply in a 1-3 inch layer over the soil (under the drip line of the plant).
Aside from providing a slow release of nutrients, the mulch will also help the soil retain water and protect it from the sun. Remember to keep the mulch at least 3 inches from the plant’s trunk to avoid any mold from spreading.
How Many Coffee Grounds Should You Use on Fig Plants?
As a general rule, keep the used coffee grounds below 15-20% of your total soil or compost content. For the occasional espresso brick, you can apply it directly. For the daily pot, considering composting it first. Using an excess with your fig plants or compost pile can create imbalances in nutrients and soil life.
If you’re composting the coffee grounds first, allow 2-3 months for them to fully decompose. After, apply the compost in 1-2 inch layers around the fig plants. Similar to the mulch, avoid touching the compost to the trunk by keeping it at least 3 inches away.
If you’re not sure how many coffee grounds to apply, it’s always a good idea to start with small amounts and work your way up gradually (or you can keep it easy and compost them first). For best results, two weeks after you apply coffee grounds, check your fig plant for any growth issues.
For example, a potential issue with using too many coffee grounds is some leaves turning yellow.
However, this is highly unlikely unless you’re using way more than the above suggested amounts (generally, above 15-20% of the soil’s total volume).
If you do find that you have extra coffee grounds to spare, and are looking to use them on other plants, consider giving them to companion plants which also benefit fig plants.
When Should You Apply Coffee Grounds to Your Fig Plants?
The best time to apply coffee grounds to fig plants is in the early spring and throughout the rest of the growing season. Avoid using coffee grounds on fig plants in the winter as the trees typically go more dormant and don’t require many nutrients. Instead, in the winter, add coffee grounds to the compost pile.
In the spring and growing months, you can apply coffee grounds to your fig plant in the ways mentioned above. However, in the winter, it’s best to add the coffee grounds to a compost pile first so the nutrients don’t go unused in the soil. Too many nutrients sitting in the soil can chemically burn the plant’s roots and negatively impact its health.
Coffee grounds add many valuable nutrients to the fig plant’s soil. Just as important, coffee grounds also greatly improve the soil’s richness and water retention. In fact, each 1% increase in the richness of the soil can help it hold 20,000 gallons more per acre.