Are Eggshells, Coffee Grounds, Or Epsom Salt Good for Houseplants? Easy DIY Houseplant Fertilizers

Making compost can reduce household waste and has been called “black gold” for the valuable nutrients compost can add to growing soil, whether indoors or outdoors. Many ingredients can be added to compost, such as newspaper, vegetable scraps, bone, Epsom salt, eggshells, and coffee grounds.

Eggshells, coffee grounds, and Epsom salt are easy DIY houseplant soil fertilizers as eggshells provide calcium, coffee grounds add carbon and nitrogen, and diluted Epsom salt adds magnesium and sulfur

While appropriate use of these elements is essential to healthy plants, it is not a cure-all for every growing dilemma. Adding too much fertilizer or concentrated compost can damage the roots rather than help the plant. 

Are Coffee Grounds and Eggshells Good for Indoor Plants?

Coffee grounds and eggshells are excellent nitrogen and calcium sources– necessary nutrients for healthy plants. You can add these elements to your homemade compost as a budget and environmentally-friendly way to nourish plants. You can also purchase a pre-mixed fertilizer with a balanced NPK score. NPK stands for nitrogen (N), phosphorus (P), and potassium (K). All plants need these nutrients, but some fertilizers offer higher nitrogen levels. 

Coffee Grounds

Used coffee grounds are fantastic natural sources of nitrogen. But do not be tempted just to sprinkle fresh coffee grounds or whole coffee beans into your soil. The coffee needs to be brewed so that the nitrogen can be released. After you enjoy your morning cup of joe, add the used grounds to the compost bin or sprinkle a few teaspoons into your houseplant’s soil. 

Used coffee grounds are pretty neutral in terms of pH. Coffee can also bring in healthy animals like worms while keeping pests like slugs and cats away. It can also help retain soil moisture if done in the right amounts.  

For coffee grounds, there are three ways you can use it to benefit your plants. You can use unbrewed coffee grounds, which are more acidic, or brewed coffee grounds that you would normally toss out. For both, all you have to do is place it on the surface or mix it into the top layer of the soil. 

You will want to be careful only to add a little at a time, as if you add too much, you might cause a water-resistant barrier in your garden. Another way you can use coffee is to make diluted coffee with used coffee grounds. It can be used as a liquid fertilizer this way. 


Crushed egg shell
If you have eggs for breakfast, that could be even better news for your plants! Finely ground eggshells can deter pests, help drain the soil, and give the plant a calcium boost. After you cook your morning eggs, crush up the shells and work them into the soil to help keep the slug and snail population at bay. You can also add them to the compost bin to add some rich calcium to your organic compost. 

Calcium found in eggshells can help prevent blossom rot in pepper and tomato plants. For succulents or other houseplants that require well-drained soil, try adding a layer of eggshells to the bottom of the plant container before adding the soil. 

Plants That Benefit From Coffee Grounds And Eggshells

Eggshells are full of calcium, so any plant that benefits from excess calcium is best. Some examples are:

  • Tomatoes
  • Peppers
  • Spider Plants
  • Eggplants
  • Broccoli
  • Cauliflower
  • Spinach
  • Swiss Chard
  • Ferns
  • Lettuce
  • Marigold
  • Ivy
  • Strawberries
  • Squash

If you plan to use coffee grounds you’ve already steeped to make your morning coffee, almost any plant will benefit from the grounds. However, you want to avoid using it on younger plants, as it can cause stunted growth. 

Also, some plants just can’t handle the toxins in coffee. Some of these plants include:

  • Broccoli
  • Leek
  • Tomatoes
  • Radish
  • Viola
  • Sunflower

Other plants enjoy acidic soil and do best with fresh coffee grounds instead of used coffee grounds:

  • Rhododendrons
  • Azaleas
  • Lily of the Valley
  • Blueberries
  • Hydrangeas
  • Carrots
  • Radishes

Epsom Salt for Houseplants

There’s a lot of debate on whether Epsom salt is beneficial for houseplants or not. Epsom salt is magnesium sulfate. So if you have plants that need a little more magnesium, then Epsom salt might be a good option for your plant. Most fertilizers don’t include magnesium, so it is an easy way to give those nutrients to your plant. 

However, you can’t just put this salt on your plant directly. Instead, you have to dilute it. One tablespoon of salt to a gallon of water is the best option, and you can pour it on like a liquid fertilizer. 

If your plant doesn’t have a magnesium deficiency, then there is no point in adding this. Too much magnesium can be just as harmful as too little. 

Easy DIY Plant Fertilizer

Compost is the easiest plant fertilizer. Take scraps of foods, teas, coffees, and more and provide a healthy mix of nutrients for your plant. Some great items to include in your compost are:

  • Eggshells
  • Grass
  • Tea
  • Coffee
  • Banana Peels
  • Seaweed
  • Manure
  • Aquarium Water
  • Vinegar

All of these items can be blended to make fertilizer, or be used by themselves, usually steeped in water, to provide your plant with a specific mineral or nutrient it might be missing. 

Frequently Asked Questions

Which Plants Like Epsom Salt?

Epsom salt
Plants that like Epsom salt usually need a higher amount of magnesium than other plants. Some plants include cucumbers, legumes, peppers, tomatoes, roses, succulents, and lettuce. 

How Can I Add Magnesium to Soil Naturally?

The most natural way to add magnesium into the soil is via compost. Compost is usually full of minerals and vitamins that your plants need, including magnesium. If you are planting a garden, mixing a bit of compost into the soil before planting can boost nutrients for your plant. 

Compost also helps prevent nutrient leaching, even in high rains, so you usually only have to apply it once a year. 

However, Epsom salt is also widely used for those that can’t compost by diluting a bit of Epsom Salt into the water; a tablespoon to a gallon of water is usually plenty. You can spray this onto the soil or the plant’s leaves. We wouldn’t recommend doing this more than once a month to avoid giving your plant too much magnesium. 

Other natural methods include Calcitic or dolomitic limestone, Sulfate of Potash Magnesia, poultry manure, and soybean meal. Remember that magnesium is something that many plants don’t need, which is why it isn’t included in traditional fertilizer. Also, it is possible to add too much magnesium and harm your plant, so use it sparingly. 

Are Eggshells Good for Indoor Plants?

Eggplants and excess calcium can be suitable for indoor plants. It helps to increase the rigidity and health of their cells and the structure of the plant. Eggshells also slow-release calcium, which is a much safer way to give your plant the calcium it needs. 

If your plant is in immediate need of calcium, eggshells aren’t the best option, as they don’t break down quickly. But they make an excellent slow release of calcium for plants that need it. 

While calcium is important, it doesn’t negate that plants still need other nutrients. Eggshells can’t replace a plant’s nitrogen, phosphorus, and potassium needs. Eggshells are more of an addition and not a replacement. 

Growing edible plants that are notoriously high in calcium, like tomatoes, squash, and strawberries, will benefit from having eggshells in the soil, along with their regular fertilizer. 

Eggshells aren’t harmful to plants since they break down so slowly. So if you aren’t sure if your plant needs extra calcium, adding some ground eggshells into their soil isn’t a bad idea. 


Epsom salt, coffee grounds, and eggshells are all-natural ways to increase the minerals and nutrients in your plant’s soil. While most plants do okay with nitrogen, phosphorus, and potassium, some plants need a little extra help with minerals like calcium and magnesium. 

Eggshells, coffee grounds, and Epsom salt are easy DIY houseplant fertilizers as eggshells provide calcium to the soil after they decompose, coffee grounds add carbon and nitrogen to the soil, while diluted Epsom salt adds magnesium and sulfur. 

These three ingredients may not be for every plant but can be very beneficial to the plants that need a little extra nutrient assistance. By mixing these items into compost, adding them into the soil, or diluting them in water, you can add more nutrients to your plants and help them thrive.