Is Potato Water Good for Plants? An In-Depth Explanation

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Potatoes are a common vegetable packed with essential nutrients and minerals. They are a perfect source of potassium, fiber, and vitamin C. While most people only think of utilizing potatoes themselves, did you know that the water they are boiled in can also be used for plants?

Potato water is good for plants as it packs a high dose of phosphorus, calcium, and magnesium, all of which are essential for healthy plant growth. It also contains over 350mg of potassium per 100g which helps plants develop immunity against environmental stress and pests.

But what exactly is in potato water that makes it so beneficial for plants? Read on as we go in-depth on potato water, including the plants that benefit most from it and plants you should avoid using it on. We will also discuss what you can do with the potato peels.

How Potato Water Benefits Plants

Potatoes are rich in essential nutrients and minerals that plants need for healthy growth. Some of the minerals contained in potato water include:

When boiling potatoes, these nutrients leach out into the water, making it an ideal liquid fertilizer for plants. The boiling water’s high temperature breaks down the potato’s skin and fibers, allowing the nutrients to dissolve easily. Each of these minerals plays a vital role in plant growth and development.


Potassium is an essential macronutrient for plants and vital for developing strong roots. Plants suffering from a potassium deficiency often display stunted growth, yellowing leaves, and poor disease resistance.

Other benefits of potassium to plants include:

  • Enhances drought tolerance and disease resistance.
  • Aids in photosynthesis by regulating the opening and closing of the stomata.
  • Stimulates plant cell division.
  • Facilitates starch and protein synthesis.
  • Reduces lodging (the tendency of plants to fall over).
  • Aids in the uptake of water and other nutrients through osmosis.


Phosphorus is another vital plant macronutrient that helps with cell growth, root development, and flowering. This mineral is often lacking in soils, especially sandy soils. A phosphorus deficiency can result in stunted growth, dark green leaves, and purpling of the foliage.

Other benefits of phosphorus include:

  • Improves stalk and stem strength.
  • Increases nitrogen-fixing capabilities in legumes.
  • Boosts disease resistance.
  • Aids in cell division and new tissue development.
  • Stimulates early root development and crop maturity.
  • Strengthens cell walls.


While calcium is a secondary macronutrient, it’s still crucial for plant growth. Calcium helps with cell wall development and strengthens plant tissue. A calcium deficiency can result in deformed leaves, stunted growth, and tip dieback.

Other benefits of calcium in plants include:

  • Improves cell permeability.
  • Stimulates photosynthesis.
  • Increases disease resistance.
  • Regulates metabolic processes.
  • Aids in the uptake of other nutrients.


Magnesium is the core of the chlorophyll molecule, giving plants their green color. This essential mineral is involved in photosynthesis, as the magnesium ion (Mg2+) is necessary for activating enzymes used in this process. Plants deficient in magnesium often display yellow leaves with green veins, stunted growth, and poor disease resistance.

Other benefits of magnesium include:

  • Activates enzymes necessary for plant growth.
  • Involved in the synthesis of proteins, nucleic acids, chlorophyll, and enzymes.
  • Aids in the uptake of other nutrients, including phosphorus and nitrogen.
  • Helps in cell division and protein development.

However, there are other benefits of potato water besides just the nutrients it contains. These include:

  • Promotes beneficial bacteria growth in the soil.
  • It neutralizes burn caused by inorganic fertilizer.
  • It is environmentally friendly and sustainable.
  • It saves you money on inorganic fertilizers.

How To Make Potato Water for Plants

Making potato water is easy and only requires a few simple ingredients. However, avoid adding salt to the water as this can damage the plants.


  • Unpeeled potatoes
  • Water
  • A large pot
  • Source of heat
  • A plastic container


  1. Thoroughly wash the potatoes with your hands to remove any dirt or debris. You can also use a vegetable brush to remove any stubborn dirt.
  2. Arrange the potatoes in the pot and fill it with water. Place the pot on top of a heat source and bring the water to a boil.
  3. Allow the potatoes to cook for about 15 to 20 minutes or until they are soft. Remove them from the heat and strain the water into another pot or container.
  4. Once the potatoes have cooled, you can peel them and keep the peels for composting. Allow the potato water to cool completely before using it on your plants. Alternatively, store it in a cool, dry place away from children and pets.
  5. When ready to use the potato water, shake it thoroughly to mix up the nutrients. You can then water your plants with it or use it as a foliar spray.

If you have salted your potato water, you can use it to kill weeds. When the weeds absorb the salt, it disrupts the water balance in their cells, causing them to wilt and die. Spray the salt water on the leaves of the weeds, making sure to avoid contact with your plants.

How To Use Potato Water on Plants

Potato water can be used on most plants, including vegetables, fruits, flowers, and herbs. It’s best to use it on younger plants as they are more likely to absorb the nutrients. You can also use it on established plants showing signs of stress, such as yellowing leaves or stunted growth.

There are two ways to use potato water on plants: watering and foliar spraying.


Watering is the most common way to use potato water on plants. To do this:

  1. Use a watering can to wet the soil around the base of the plant.
  2. Avoid wetting the leaves as this can encourage fungal growth.
  3. Apply the potato water to the soil until it’s saturated and make sure to avoid sogginess as this can lead to root rot.
  4. Water your plants 2-3 times a week or as needed.

Foliar Spraying

Foliar spraying refers to the process of applying the potato water directly to the plant’s leaves. This is an excellent way to give plants a quick boost of nutrients, especially if they show signs of stress or struggle to absorb nutrients through their roots. To foliar spray:

  1. Fill a clean spray bottle with potato water and shake it well to mix up the nutrients.
  2. Spray the leaves of the plant, making sure to avoid contact with the stem or flowers.
  3. Apply the spray in the morning, so the leaves have time to dry before nightfall.
  4. Repeat every 2-3 days or as needed.

Plants That Benefit the Most From Potato Water

While potato water is suitable for most plants, some benefit from it more than others. These plants include:

  • Vegetables such as tomatoes, potatoes, eggplants, cucumbers, beans, lettuce, spinach, kale, cabbage, broccoli, and cauliflower
  • Herbs like mint, rosemary, basil, mint, and oregano
  • Flowers such as roses, daisies, and impatiens

Plants That You Should Not Use Potato Water On

Conversely, there are also some plants that you should not use potato water on as it can harm them. Since potato water is high in potassium, it can cause a nitrogen deficiency that stunts the plant’s growth and causes chlorosis.

Potato water is also high in starch, which can encourage the growth of bacteria and fungi, especially in warm weather. Most potted plants are also susceptible to this as they have poor drainage. Plants you should avoid using potato water on include:

  • Young plants that have not yet been transplanted
  • Seedlings
  • Potted plants with poor drainage
  • Plants susceptible to powdery mildew or other fungal diseases

Generally, it’s best to err on the side of caution and only use potato water on plants that you know will benefit from it. If unsure, it is always best to consult a gardening expert.

When To Apply Potato Water

Proper timing is essential when using potato water on plants. The best time to apply it is in the morning or evening when the sun isn’t as intense. This prevents the water from evaporating too quickly and gives the plant time to absorb the nutrients.

If you’re foliar spraying, spray in the morning, so the leaves have time to dry before nightfall. Accumulation of water on the leaves overnight can encourage fungal growth.

Avoid overwatering your plants as this can lead to root rot. To check whether your plant needs water, stick your finger 2-3 inches in the soil. If the soil is dry to the touch or its particles fall off easily, it’s time to water. However, if the soil is still moist or the particles stick to your fingers, wait a day or two before watering again.

You can use potato water on your plants 2-3 times a week or as needed. If you notice that your plants are wilting or showing signs of stress, you can increase the frequency to 4-5 times a week.

How To Store Potato Water

Chances are, you’ll not use all the potato water at once. After boiling the potatoes, let the water cool completely before storing it in a clean, airtight container. You can store potato water in the refrigerator for up to 1 week. Alternatively, you can keep it in a cool, dark place such as a basement or garage.

Storing the water in an airtight container prevents bacteria growth, which can be harmful to your plants. Avoid over-storage as it can alter the pH levels and make the water less effective. Before using, give the water a good shake or stir to mix up the nutrients.

What To Do With the Potato Peels

After boiling the potatoes, you’ll be left with many potato peels. These peels contain a high concentration of nutrients that can be beneficial to your plants. There are two ways you can use them:

  • Composting
  • Mulching


Composting is the process of breaking down organic matter such as leaves, grass, and food scraps. It creates nutrient-rich compost that can be used as a natural fertilizer for your plants.

To compost potato peels:

  1. Add the peels to your compost bin or pile.
  2. Mix in some other organic matter such as leaves, grass, and food scraps.
  3. Keep the compost moist but not soggy.
  4. Cover with a tarp or lid to retain moisture.
  5. Stir or turn the compost every few days.
  6. When the bottom of the pile is dark and crumbly, it’s ready to use.
ID 209894860 | © Maryna Hlushko |


Alternatively, you can apply the potato peels directly to the garden as mulch. Mulching is the process of covering the soil around your plants with a layer of material. This can be anything from leaves to straw.

Mulch helps to retain moisture, suppress weeds, and protect your plants from extreme temperatures. Over time, the potato peels break down and decompose, adding nutrients to the soil and improving its quality.

To use potato peels as mulch:

  1. Spread a 2-3 inch (5-8 centimeters) layer around the base of your plants.
  2. Avoid covering the stems or leaves as this can encourage fungal growth. While making sure to leave about 1-inch (2.54 cm) of space around the plant.
  3. Replenish the mulch as the peels decompose.

How To Use Boiled Vegetable Water on Plants

In addition to potato water, you can also use the water from other boiled vegetables such as carrots, tomatoes, and spinach. These vegetables contain a variety of nutrients, including iron, magnesium, and calcium, all of which are essential for plant growth. Like in potato water, the nutrients are released when the vegetables are boiled.

To use boiled vegetable water on plants:

  1. Strain the water to remove any pieces of vegetable.
  2. Let the water cool completely before using it on your plants.
  3. Apply to your plants using a watering can or spray bottle.
  4. Store the water in a clean, airtight container in the refrigerator for up to 1 week.
  5. Remember to shake or stir the water before using the liquid to mix up the nutrients.


Using potato water to water your plants is an easy and affordable approach to provide them with a nutrient boost. This environmentally friendly method is simple and doesn’t require any special ingredients or equipment. You can apply the liquid to your plants by watering directly with a watering can or by using a spray bottle. Water your plants in the morning or in the evening to avoid rapid evaporation.

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