How to Balance pH for Coreopsis: A Step-by-Step Guide

Coreopsis, also known as tickseed, is a beautiful and vibrant flowering plant that adds a splash of color to any garden. To ensure your Coreopsis thrives and blooms to its fullest potential, it’s essential to maintain the proper soil pH balance. In this comprehensive guide, we’ll walk you through the steps to test, amend, and monitor the pH levels for optimal Coreopsis growth.

What Is the Ideal pH Range for Coreopsis?

Coreopsis prefers slightly acidic to neutral soil, with a pH range between 5.5 and 6.5. This range allows the plant to absorb the necessary nutrients from the soil efficiently, promoting healthy growth and abundant blooms.

How to Test Soil pH for Coreopsis


To determine the current pH level of your soil, you can use a soil pH testing kit or take a sample to your local garden center for analysis. Home testing kits are readily available at most garden supply stores and are simple to use:

  1. Collect soil samples from various locations in your Coreopsis bed, digging down to a depth of 6 inches.
  2. Mix the samples together in a clean container.
  3. Follow the instructions provided with your pH testing kit to obtain an accurate reading.

Amending Soil pH for Coreopsis

If your soil pH falls outside the ideal range for Coreopsis, you’ll need to amend the soil accordingly. Here’s how to adjust the pH:

Lowering Soil pH for Coreopsis

To lower the soil pH, you can use elemental sulfur or aluminum sulfate. Apply the amendment at a rate of 1 pound per 100 square feet for every point below 5.5 you want to lower the pH. For example, if your soil pH is 7.0 and you want to lower it to 6.0, you’ll need to apply 1.5 pounds of elemental sulfur or aluminum sulfate per 100 square feet.

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Raising Soil pH for Coreopsis

To raise the soil pH, incorporate lime into the soil at a rate of 5 pounds per 100 square feet for each point above 6.5 you wish to raise the pH. For instance, if your soil pH is 5.0 and you want to raise it to 6.0, you’ll need to apply 5 pounds of lime per 100 square feet.

When amending the soil, mix the amendment thoroughly into the top 6 inches of soil. Water the area well after application to help the amendment penetrate the soil.

Monitoring Soil pH for Coreopsis

Coreopsis 2

After amending the soil, it’s crucial to monitor the pH regularly to ensure it remains within the optimal range for Coreopsis. Retest the soil pH annually or after heavy rainfall, as these events can significantly affect the soil pH. If necessary, make additional adjustments to maintain the ideal pH range.

Additional Care Tips for Coreopsis

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

  • Sunlight: Coreopsis requires at least six hours of direct sunlight per day. While it can tolerate some partial shade, full sun is ideal for optimal growth and blooming.
  • Temperature: The ideal temperature range for Coreopsis is between 60°F and 75°F (15°C and 24°C). They can tolerate slightly higher temperatures but may require additional watering during hot spells.
  • Watering: Water your Coreopsis deeply and regularly during the growing season, allowing the soil to dry slightly between waterings. Reduce watering frequency during the winter months to prevent root rot.
  • Fertilizing: Coreopsis benefits from a balanced, slow-release fertilizer applied once a month during the growing season. Avoid over-fertilizing, as this can lead to excessive foliage growth at the expense of blooms.
  • Pruning: Deadhead spent flowers regularly to encourage continuous blooming throughout the season. Prune back the plant by about one-third in late fall or early spring to maintain a compact shape and promote healthy growth.
  • Dividing: Divide Coreopsis plants every 2-3 years in early spring or fall to maintain vigor and prevent overcrowding. Carefully dig up the clump, separate the roots, and replant the divisions, ensuring each has a healthy portion of roots and foliage.
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How Long Does It Take to Balance Soil pH for Coreopsis?

The time required to balance soil pH for Coreopsis depends on the initial pH level and the amount of amendment needed. In general, it takes several weeks to a few months for the soil pH to stabilize after amending. Regular monitoring and retesting will help you track the progress and make any necessary adjustments.

Home Remedies for Adjusting Soil pH for Coreopsis

In addition to commercial amendments, there are some home remedies you can use to adjust soil pH for Coreopsis:

  • Coffee Grounds: To lower soil pH, mix used coffee grounds into the soil around your Coreopsis plants. The grounds are slightly acidic and can help lower the pH over time. Apply a 1-inch layer of coffee grounds and work them into the top 6 inches of soil.
  • Wood Ash: To raise soil pH, sprinkle wood ash around your Coreopsis plants. Wood ash is alkaline and can help increase the pH of acidic soils. Apply a thin layer (about 1/4 inch) of wood ash and mix it into the top 6 inches of soil. Be cautious not to overuse wood ash, as it can lead to nutrient imbalances if applied in excess.

Remember, home remedies may take longer to affect soil pH than commercial amendments, and their effectiveness can vary. It’s essential to monitor the soil pH regularly and make adjustments as needed.

By following this step-by-step guide and providing proper care, you can successfully balance the soil pH for your Coreopsis plants, ensuring they thrive and produce a stunning display of vibrant blooms year after year.

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