How to Balance pH for Watercress: A Comprehensive Guide

Watercress is a delicate, aquatic plant that requires specific growing conditions to thrive. One of the most crucial factors in growing healthy watercress is maintaining the proper pH balance in the water and soil. In this comprehensive guide, we will discuss how to balance pH for watercress, including the ideal pH range, methods for adjusting pH, and tips for maintaining optimal growing conditions.

The Ideal pH Range for Watercress

Watercress grows best in a pH range of 6.5 to 7.5. This slightly acidic to neutral pH range allows the plant to absorb nutrients efficiently and prevents the growth of harmful bacteria and fungi. To ensure your watercress is growing in the proper pH range, it is essential to regularly test the water and soil using a reliable pH meter.

Adjusting pH in Water for Watercress

water cressImage source: Pixabay

If the pH of your water is too low or too high, you can use various methods to adjust it. One simple and effective method is to use baking soda to raise the pH or lime/limestone to lower it.

Using Baking Soda to Raise pH

To raise the pH of your water using baking soda, follow these steps:

  1. Mix one teaspoon of baking soda into a gallon of water.
  2. Stir the solution until the baking soda dissolves completely.
  3. Test the pH of the water using a pH meter.
  4. If the pH is still too low, add another half teaspoon of baking soda and repeat the process until the desired pH is reached.

Be cautious not to use too much baking soda, as it can raise the pH too high and harm your watercress plants.

See also  How to Balance pH for Turk's Cap Lily

Using Lime or Limestone to Lower pH

If the pH of your water is too high, you can use lime or limestone to lower it. Lime and limestone contain calcium carbonate, which helps to neutralize the alkalinity of the water. To use lime or limestone, follow these steps:

  1. Add a small amount of lime or limestone to your water, following the manufacturer’s instructions.
  2. Stir the water thoroughly to ensure the lime or limestone is evenly distributed.
  3. Test the pH of the water using a pH meter.
  4. If the pH is still too high, add more lime or limestone gradually until the desired pH is reached.

Maintaining Optimal Growing Conditions for Watercress

In addition to maintaining the proper pH balance, there are several other factors to consider when growing watercress:

Soil and Potting Mix

Watercress grows best in a soilless potting mix containing perlite or vermiculite mixed with peat. The potting mix should be kept consistently moist. If growing watercress in pots, place the pot in a saucer filled with water to ensure the soil remains moist. Determine the fertilizer needs of your watercress plants by conducting a soil test and following the recommendations provided in the test report.

Weed Control and Mulching

Keep the area around your watercress plants free from weeds and apply a light layer of mulch to help maintain moist soil conditions. This will also help to prevent the growth of competing plants that may rob your watercress of essential nutrients.

Pest Control

While watercress is relatively resistant to diseases in most production settings, it can be susceptible to pests such as white flies, spider mites, and snails. To control white flies, which are found underneath the leaves, use a solution of soapy water or insecticidal soap. Spider mites cause flecking, discoloration, and scorching of leaves and can be controlled by introducing natural predators such as small lady beetles, predatory mites, and predatory thrips. Snails can be removed by hand, controlled with a molluscide, or trapped.

See also  How to Balance pH for Juniper: A Step-by-Step Guide

Water Flow and Temperature

Watercress grows best in slow-flowing, but not stagnant, water. The recommended water flow rate for growing watercress is 720 L/h per 0.3 m width of bed. While some people recommend growing watercress in the shade to allow the roots to “breathe,” research shows that the more sun (light) a plant receives, the larger it grows. Flowing water helps to bring oxygen to the roots, which is essential for healthy growth.

Measuring Local Environmental Conditions

To optimize the growing environment for your watercress, it is important to measure local environmental conditions such as water flow, water temperature, water pH, nitrate levels, light levels, and soil/sediment composition. By comparing and contrasting the best and worst watercress growing areas, you can identify what factors limit watercress growth and take steps to improve the site and increase growth. Measure light intensity, shading, sunlight time, site aspect, and steepness to determine how these factors influence the growing environment of your watercress.


water cress 2Image source: Pixabay

Balancing the pH for watercress is essential for ensuring healthy growth and optimal yields. By maintaining a pH range of 6.5 to 7.5, keeping the growing area free from weeds, mulching lightly, controlling pests, and providing the proper water flow and temperature, you can create the ideal growing conditions for your watercress plants. Remember to regularly test the pH of your water and soil and make adjustments as needed using baking soda or lime/limestone. With proper care and attention to detail, you can enjoy a bountiful harvest of fresh, healthy watercress.

See also  How to Balance pH for Strawberries: A Comprehensive Guide


  1. Watercress in the Garden
  2. Keeping Our Watercress Safe
  3. How to Adjust Water pH for Plants
  4. How to Grow Watercress Indoors and Outdoors