Stella d'Oro Day Lily pH Requirements

Soil pH and Growing Conditions

• Stella d'Oro day lilies, like all day lilies, prefer a slightly acidic soil with a pH between 6.0 and 6.5; however, they'll thrive in almost any soil as long as it is well-draining. Most plants, including Stella d'Oro day lilies, can tolerate some variances in soil pH. Day lilies are among the most adaptable perennials and often grow wild alongside ditches. Amend the soil with compost or manure to improve its drainage, and plant these long-lived perennials in full sun. Although they tolerate drought, they grow better with regular moisture. With proper care, day lilies usually thrive regardless of your soil pH.

Why Soil pH Matters

• Alkaline soils are those with a soil pH above 7.0. These soils are typically found in inland locations that get little rain. Acidic soils are typically found in coastal regions or areas that get a lot of rainfall. These soils have a pH below 7.0. A neutral soil has a soil pH of 7. Soil pH matters because, as the soil pH rises above or falls below neutral, certain nutrients are less available to plants. In highly alkaline soils, for example, iron is often unavailable, and plants develop iron chlorosis, or yellowing of the leaves. Magnesium is often unavailable in acidic soils, which can contribute to problems such as blossom end rot on vegetables.

When to Worry

• It's a good idea to test your soil every few years with a soil pH test available at garden centers or through private labs and university extension offices. The results of this test can guide fertilizer applications and plant selections. At pH levels above 7.4, iron becomes unavailable to plants, and your Stella d'Oro day lilies might suffer iron deficiencies. Soil microbial activity is reduced when soil pH falls below 5.6. If your soil pH falls in either of these extremes, you probably need to make modifications not just for your day lilies but also for most of the plants growing in your garden.

Altering Soil pH

• Adjusting the soil pH can take several months or even a year. To lower the soil pH, elemental sulfur is dug into the soil to a depth of at least 6 inches. The amount of sulfur to use varies, depending on your soil type, but in general, you'll need 1 1/2 to 2 pounds of elemental sulfur per 100 square feet for each scale interval raised. On clay soils, you'll need more; sandy soils require less. To raise the pH of acidic soil, dig dolomitic lime in at a rate of 5 to 10 pounds per 100 square feet of soil. Again, clay soils need more lime than sandy ones. When in doubt, the results from a soil pH test provide the most accurate directions.