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What does baking soda do for plants?

Baking soda, also known as sodium bicarbonate, is a versatile household product with many uses. One of its lesser-known applications is as a supplement for plants and gardens. When used correctly, baking soda can provide multiple benefits for plants and soils.

How does baking soda affect plant growth?

Baking soda affects plants in several ways. First, it can raise the pH level of acidic soils closer to the ideal range of 6.0-7.0 for most plants. Many plants prefer to grow in slightly alkaline soils rather than acidic soils. Baking soda is an alkaline substance, so sprinkling it onto soil can increase alkalinity.

Second, baking soda possesses antifungal properties that may suppress some common fungal diseases in plants. By sprinkling baking soda onto soil, it can come into contact with fungal spores and hyphae, inhibiting their growth and spread. This can prevent fungal issues like powdery mildew, root rot, and blights in some cases.

Third, baking soda may provide plants with supplemental calcium and magnesium when used as a foliar spray. Calcium and magnesium are essential nutrients for plant growth and health. Baking soda dissolved into water can potentially supply some of these minerals.

Fourth, baking soda is thought to stimulate plant immune systems when applied to leaves and stems. By triggering increased production of antioxidants and defense proteins, baking soda may boost plants’ natural defenses against diseases and pests.

How to use baking soda in gardens

There are several methods for using baking soda in gardens and on houseplants. Key tips include:

  • Soil amendment – Mix 1 teaspoon baking soda per 2 gallons of water and apply to soil. Can be used 2-4 times per growing season to neutralize acidic soils.
  • Foliar spray – Mix 1 teaspoon baking soda per 1 quart of water and spray leaves. Can be used every 2-4 weeks to prevent fungal disease and supplement nutrients.
  • Transplant soaking – Add 1 teaspoon baking soda per 1 quart of water and soak new transplants’ roots before planting. Reduces transplant shock.
  • Compost activator – Sprinkle 2 tablespoons baking soda per 1 cubic foot of compost pile. Helps speed decomposition and reduce odors.

Too much baking soda can harm plants, so always start with light applications and increase slowly as needed. Target applications to soil or foliage, not both at the same time.

What are the benefits of baking soda for plants?

When used properly, baking soda can provide the following benefits for plants:

  • Increases soil alkalinity – Counteracts acidic soils which stunt plant growth
  • Suppresses fungal diseases – Prevents issues like root rot, powdery mildew, and blights
  • Adds supplemental nutrients – Provides calcium, magnesium, and sodium
  • Stimulates plant defenses – Triggers increased production of protective antioxidants and proteins
  • Reduces transplant shock – Minimizes stress for new transplants adjusting to a new environment
  • Improves compost – Speeds decomposition and reduces odors from compost piles

These effects can result in healthier root systems, greener foliage, better flowering and fruiting, and enhanced resistance to common plant diseases. Baking soda is not a cure-all, but it can be a helpful supplement when used properly.

What plants respond well to baking soda?

Most plants can benefit from judicious baking soda applications. Plants that typically appreciate baking soda include:

  • Azaleas
  • Hydrangeas
  • Roses
  • Tomatoes
  • Peppers
  • Eggplants
  • Squash
  • Melons
  • Cucumbers
  • Lettuces
  • Beans
  • Carrots

These plants often prefer slightly acidic to neutral soil pH, which baking soda can help provide. They also frequently suffer fungal issues that baking soda may help suppress. Providing baking soda can result in more abundant blooms and enhanced vegetable yields.

What are the side effects of too much baking soda on plants?

While baking soda can benefit plants in moderation, too much can negatively impact gardens. Potential side effects of excessive baking soda application include:

  • Raises soil pH too high – Ideal pH is 6.0-7.0, but too much baking soda can cause excess alkalinity
  • Prevents nutrient absorption – High pH prevents uptake of iron, manganese, zinc, copper, and boron
  • Causes sodium buildup – Excess sodium harms soil structure and inhibits water uptake
  • Leaves salt residue on foliage – Can burn leaves or cause leaf margin scorching

Maintaining a balanced soil environment is important for plant health. While pH adjustment with baking soda can be helpful, overdoing applications can swing levels too far in the wrong direction.

How does baking soda affect different types of plants?

Baking soda affects various types of plants in the following ways:


Many vegetables grow best in slightly acidic soils from 6.0-6.5 pH. Baking soda can help keep soils in this range, supporting better yields. It also suppresses fungal issues like powdery mildew that can affect yields and quality.


Blueberries and strawberries prefer more acidic soils below 6.0 pH. Baking soda is generally not recommended for these crops. Other fruits like tomatoes, cucumbers, and melons appreciate pH levels baking soda provides. It also helps control fungal diseases.


Most culinary herbs grow well in neutral to slightly alkaline soils. Baking soda can raise pH for herbs like basil, thyme, parsley, and cilantro. It also limits problems with fungal diseases like root rot.


Many flowering plants thrive in neutral to mildly acidic conditions. Baking soda provides an ideal pH environment for growing vibrant flowers. It also combats issues like powdery mildew that can damage blossoms and leaves.


Flowering shrubs like hydrangea, rhododendron, and azalea need acidic soils below 6.5 pH. Too much baking soda can raise pH too high for these shrubs, resulting in inhibited flowering. Use with caution and amend soil with sulfur instead if needed.


Most trees tolerate a wider pH range and can benefit from baking soda’s antifungal effects. Conifers and pine trees prefer more acidic soils, so baking soda is not recommended for them. Limit use to avoid overly alkaline soils.

What are other ways to change soil pH?

While baking soda can raise pH, gardeners can use other products to lower pH if needed:

  • Sulfur – Sprinkled onto soil, sulfur reacts to form acids that lower pH.
  • Peat moss – Mixed into soil, decompose peat releases organic acids that reduce pH.
  • Coffee grounds – Contain acids that gradually lower pH as they break down.
  • Pine needles – Decomposing needles increase soil acidity like peat moss.
  • Wood ash – Contains calcium carbonate that increases pH like baking soda.
  • Lime – Added to soil, lime provides calcium carbonate to raise pH.

Using a combination of products allows adjusting soil pH up or down as needed for ideal growing.

What are signs a plant needs baking soda?

Indications a plant may benefit from baking soda include:

  • Yellowing leaves – Can indicate low soil pH preventing nutrient uptake
  • Poor flowering and fruiting – May be caused by acidic soil conditions
  • Stunted growth – A sign of reduced availability of nutrients
  • Fungal leaf spots or root rot – Fungal diseases baking soda can help suppress

These symptoms can have other causes, but improving soil environment with baking soda is worth trying before resorting to fungicides or other measures.

Should baking soda be used on all plants?

Baking soda should not necessarily be used on all plants in a garden. Some types of plants that prefer acidic soils may be harmed by raising soil pH too much. Blueberries, azaleas, rhododendrons, hydrangeas, and conifers are examples of acid-loving plants that could be damaged by too much baking soda.

The ideal approach is to test each type of plant and amend the soil accordingly. Use baking soda sparingly on acid-lovers and avoid entirely for plants like blueberries. Use it more freely in the soil for vegetables and herbs that appreciate neutral to mildly alkaline conditions.


When used properly, baking soda can be a simple, inexpensive way to improve garden soil health and plant vigor. Its alkalinity counters soil acidity, while providing antifungal benefits for plant diseases. However, over-application can negatively impact plants that prefer acidic conditions. Know the ideal soil pH for crops before applying baking soda. Target light, periodic applications to enhance plant growth and productivity.