Houseplants have exploded in popularity over the last decade, but many people are unknowingly harming their leafy companions with well-intentioned—but misguided—fertilizer choices. Just because something is “natural” doesn’t mean it’s right for every plant. In fact, using the wrong type of fertilizer can lead to root rot, pest infestations, or nutrient imbalances that slowly kill your plant. And while you might feel like you're giving your plants a little love, you could actually be stressing them out.
From coffee grounds to banana peels, there’s no shortage of DIY plant food options—but the key is knowing which plant actually benefits from which additive. Below is your detailed, no-nonsense guide to the most common natural fertilizers, what they do, and—most importantly—what plants to use them on and which to avoid.
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1. ☕ Coffee Grounds
Why: High in nitrogen, good for foliage growth—but holds moisture.
How to Use: Mix 1 tablespoon of used grounds into 1 cup of compost or potting mix every 4–6 weeks. You can also brew a weak "coffee tea" by soaking 1–2 tablespoons of grounds in 1 quart of water overnight, then strain and water your plants with it once a month.
Best Used On: Pothos, Spider Plant, Philodendron, Boston Fern.
Avoid On: Succulents, cacti, ZZ Plant, Snake Plant—prone to rot in damp soil.
2. 🥚 Eggshells
Why: Add calcium and lower soil acidity.
How to Use: Rinse and dry eggshells, crush into fine powder (coffee grinder works best). Mix 1 tablespoon per plant into topsoil or steep 5–6 crushed shells in 1 quart of water overnight and use the liquid monthly.
Best Used On: Calathea, Monstera, Spider Plant, Begonia, indoor tomato plants.
Avoid On: Gardenias, Azaleas, Peace Lily—these thrive in acidic soil.
3. 🍌 Banana Peels
Why: Rich in potassium and phosphorus for blooms and root health.
How to Use: Chop finely or blend into a puree and mix 1 tablespoon into soil once every 4–6 weeks. Or steep chopped peel in water for 2–3 days, strain, and use as liquid feed.
Best Used On: African Violets, Orchids, Peace Lily, Bird of Paradise.
Avoid On: Succulents, Snake Plant, ZZ Plant—low nutrient needs and rot-prone.
4. 💦 Rice Water
Why: Starch and trace minerals feed soil microbes.
How to Use: Collect water from rinsing or boiling unsalted rice. Let cool and use to water plants once every 1–2 weeks.
Best Used On: Peace Lily, Pilea, Philodendron, Ferns, Spider Plant.
Avoid On: Succulents, cacti, ZZ, Snake Plant—don’t like excess moisture.
5. 🧂 Baking Soda (Diluted)
Why: Natural antifungal that helps treat powdery mildew.
How to Use: Mix 1 teaspoon of baking soda + 1 quart of water + a drop of dish soap. Spray lightly on leaves once a month as a preventative or treatment.
Best Used On: African Violets, Spider Plant, Geraniums, Begonias.
Avoid On: Acid-loving plants like Ferns, Gardenias, Calatheas—can raise pH too much.
6. 🥕 Vegetable Scraps (Compost)
Why: Full-range nutrients for long-term health.
How to Use: Compost kitchen scraps (carrot peels, lettuce ends, etc.) until fully broken down. Mix ½ cup compost into potting mix or use as a top dressing every 6–8 weeks.
Best Used On: Monstera, Fiddle Leaf Fig, indoor tomatoes.
Avoid On: Succulents, cacti, bonsai—can cause overfertilization.
7. 🧅 Onion Skin Tea
Why: Natural source of potassium, calcium, and sulfur.
How to Use: Boil 1 cup of onion skins in 1 quart of water, let steep overnight, cool, and strain. Use once a month as a foliar spray or root drench.
Best Used On: Peace Lily, Bird of Paradise, Orchids.
Avoid On: Ferns, Calatheas—sensitive to strong-smelling fertilizers.
8. 🥔 Potato Water (Unsalted)
Why: High in potassium, supports growth.
How to Use: After boiling potatoes (no salt!), let water cool completely. Use 1 cup per plant every 2–3 weeks.
Best Used On: Pothos, Philodendron, Spider Plant.
Avoid On: Succulents, cacti—too much moisture, and starch can mold.
9. 🌻 Epsom Salt (Magnesium Sulfate)
Why: Helps green up yellowing leaves and supports nutrient absorption.
How to Use: Dissolve 1 tablespoon of Epsom salt in 1 gallon of water. Water plants once every 4–6 weeks.
Best Used On: Fiddle Leaf Fig, Monstera, Peace Lily (if magnesium-deficient).
Avoid On: Plants already thriving in nutrient-rich soil—ZZ, Snake Plant.
10. 🍏 Apple Cider Vinegar (Highly Diluted)
Why: Acidifies alkaline soil; ideal for acid-loving plants.
How to Use: Mix 1 teaspoon of apple cider vinegar in 1 gallon of water. Use once every 4–6 weeks during active growth.
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Best Used On: Gardenia, Azalea, Calathea, Ferns.
Avoid On: Succulents, Jade, Spider Plant—can make soil too acidic.