A Guide to Watering Plants with Coffee + [Is It Worth It?]

watering plants with coffee

Curious about watering plants with coffee? This post covers everything you need to know.

So you think you love coffee? Try giving it to your plants! Most people prefer drinking coffee to wake up and remain productive throughout the day. However, after having their fill and there’s leftover, they throw it away.

According to plant experts, coffee contains nitrogen that would benefit plants, especially those growing on acidic soil. Fortunately for the gardener who can’t skip on the daily cup of coffee, their favorite coffee store is likely to give out the coffee grounds freely as it is a waste to them.

Nonetheless, some gardeners also expressed their disappointment in using coffee on their plants. So, should you use coffee to water your plants or not? Read on for a detailed guide that will help you make a wise decision to benefit your plants.

Can You Use Coffee to Water Plants?

Well, coffee as fertilizer should not be shocking or news to you! Moreover, you can use coffee on your plants in two different ways; coffee grounds or liquid coffee.

Coffee Grounds

Most definitely, you have come across gardeners using coffee grounds in compost piles. Coffee grounds are a significant source of nitrogen in your compost pile, whereby it decomposes together with other organic matter to produce an excellent nourishing soil. Better yet, you can add it directly to the garden soil.

If added in equally large amounts, the grounds can increase the soil’s acidity level for plants like blueberries, rhododendrons, azaleas, and more. This is because the sprinkled grounds on the soil around acid-loving plants act as a mild acid fertilizer. In well-put terms, coffee grounds contain about 2% nitrogen, an essential component for growing healthy plants.

Composting grounds provide microbes that break down and let out the nitrogen. Consequently, it increases the temperature of the pile and helps in eliminating weed seeds and pathogens. Besides, worms also love the coffee grounds you use either in your garden or compost stack. Very useful indeed! 

Coffee grounds also make perfect mulch around plants or seeds. While mulch is very beneficial to a growing plant, it would be challenging to afford the straw and other organic matter in large amounts. So, why not take advantage of the free coffee grounds?

Some gardeners claim that using coffee grounds directly on the soil has adverse effects on the plant. But this would be because they tend to apply thick blankets of coffee around the plants as mulch.

This is because coffee beans have caffeine, which tends to overpower the growth of other plants to cut competition for space, water, nutrients, and sunlight. However, it will be hard to know how much caffeine remains in used coffee grounds; and some plants tend to be sensitive than others to caffeine. Therefore, it would be best to avoid spreading coffee grounds, especially around seeds or seedlings, as they are likely to hinder proper germination and growth.

Moreover, it can serve as an effective natural preventive for slugs. This way, the coffee grounds have an abrasive texture that is likely to bruise the soft-bodied slugs, or the caffeine is harsh and repellent. The slugs took seconds to avoid going close to the grounds from the research that had coffee grounds before slugs.

Apart from keeping off stray cats that mess in your garden, large amounts of coffee can harm dogs. However, it is hard to ascertain the precise level of large quantities as caffeine varies on different grounds. So, if your dog loves tasting or eating anything that smells nice, it would be best to bury your compost heap instead of laying it above the ground.

Liquid Coffee

Even though you love coffee and take it every day, you can’t help but get full and have some leftovers. Because it’s not nice to throw food away, it would be normal to wonder if you can pour the remaining coffee into the potted plant on your kitchen window.

Well, maybe yes or no! Your answer rests on the type of plant. Typically, acid-loving plants would enjoy weekly coffee watering. Moreover, outdoor plants that love acidic soil will thrive better with occasional cold coffee watering. Better yet, if your compost pile has become too dry, you can water it down with liquid coffee for better curing.

It would be better to keep be keen on your plant if you decide to use coffee for watering. Why so? When the leaves begin yellowing or turning brown, this shows that the coffee is causing excess acidity to the soil.

In addition, if you prefer a strong cup of coffee, diluting it with water would also do fine. Most office plants survive on coffee watering from left-overs in the cups or coffee pots, and they still thrive well ultimately. Besides, brewed coffee also contains significant magnesium and potassium, which are also crucial for plant growth. Without a doubt, it will be logical to conclude that using coffee to water your plants is pretty beneficial.

Caution: Don’t use the cup of coffee in front of you just yet! Most people prefer adding cream, milk, flavoring, and sugar to making their coffee. Natural sugar would not cause harm to the plants, but the other ingredients would not mean any good. You will drive your plant to get a significant infection of fungal gnats from flavored or sweetened coffee.

How to Use Coffee Watering On Plants

Typically, coffee contains a pH of 5.2 to 6.9, depending on how you choose to prepare it. While it is acidic, it means that the level of acidity increases when the pH value is low. You will also find that plants prefer slightly acid to neutral pH (5.8 to 7) soils to thrive best. On the other hand, tap water has a pH greater than 7, which makes it alkaline.

In other words, it means that watering your plants with diluted coffee is likely to raise the acidity of the soil. Nonetheless, there are ways of decreasing the pH levels of the soils, such as adding sulfur, allowing leaves to decompose on the ground, and traditional chemical fertilizers. Still, the other option would be cooling down brewed coffee and then dilute it with an equal amount of cold water as coffee. Then water away.

Acid-loving plants include:

  • African violets
  • Aloe
  • Amaryllis
  • Azaleas
  • Begonias
  • Bromeliad
  • Cyclamen
  • Ferns
  • Gardenia
  • Gladiolus
  • Hyacinth
  • Hydrangea
  • Impatiens
  • Phalaenopsis orchid
  • Roses

Remember to water with coffee just the same way you would with water. Even though indoor plants love coffee watering more, you can also use it on outdoor plants as long as they are acid-loving. Diluted coffee adds adequate organic fertilizer that will ensure healthier and bushier growth.

Parting Shot

As observed above, watering plants with coffee is easy. Besides, why should you waste your leftover coffee while it can be an ideal source of nutrients? Also, it’s a great way to cut down your costs in caring for your indoor plants. The trick is watering with coffee on the right plants, start slow and see how it all goes down. You may not be the only one with love for coffee in the house!