Achieve Sturdier Stems and Better Blooms with Proper Peony Fertilization

Peonies are a popular choice for gardeners who desire long-lasting perennials with beautiful blooms and deer-resistant foliage. Fertilizing peonies is a crucial step in ensuring their health and vitality. In this article, we will delve into the world of peony plant nutrition, including the best products, timing, and techniques to optimize their growth.

The Benefits of Proper Peony Fertilization

Properly fertilizing your peony plants offers numerous advantages. While peonies are generally robust, inadequate nutrition can result in weak stems, underdeveloped plants, and diminished flower production. On the other hand, well-fed peonies produce thicker, sturdier stems and more abundant flower buds. Additionally, their leaves exhibit a vibrant, dark green color rather than a pale, soft green shade.

Fertilizing peonies also enhances their resistance against drought and fungal diseases like gray mold and powdery mildew. Furthermore, it helps maintain the ideal pH range of 6.5 to 7 for peony-friendly soil conditions. Regardless of the peony varieties you grow, the fertilization tips discussed in this article are applicable.

Start with Compost

As is the case for most perennial plants, the organic matter in the soil surrounding the peony roots is the primary source of nutrients. This organic matter undergoes processing by soil microbes, releasing a wide array of plant nutrients. To provide this essential nutrition, apply a one-inch-thick layer of compost to your garden beds each season. Apart from enriching the soil structure, compost also nourishes your peony plants.

Some gardeners prefer using compost as a mulch to suppress weed growth around perennials and other plants. However, remember to avoid direct contact between compost (or any other mulch) and your peony plants. Instead, spread the compost around the new shoots or create a compost “donut” around the crown of the plant. This precaution prevents crown rot, which can occur when mulch accumulates on top of plants.

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Ideal Times for Fertilizing Peonies

There are two optimal periods for fertilizing peonies with a granular fertilizer.

  1. Early spring, when the new growth of emerging peony stems reaches a height of 12-16 inches (30-40 cm). Fertilizing peonies at this stage supports the current year’s growth, enhances hardiness and resilience, and promotes root development.

  2. Immediately after the flowers fade. Fertilizing at this point in the growing season strengthens the foliage, which provides carbohydrates to the roots throughout the rest of the season. This carbohydrate supply encourages “eyes” to form on the peony roots, leading to more blooms in the following year.

While some gardeners fertilize at both of these times, one annual feeding is generally sufficient, especially when utilizing slow-release fertilizers that provide nutrients over an extended period. Choose the timing that suits you and your garden best, keeping in mind the advantages and considerations associated with each period.

The Best Peony Fertilizers

In addition to compost, consider using a granular peony fertilizer each year. A suitable peony fertilizer should contain balanced macros (nitrogen, phosphorus, and potassium) along with trace elements and minerals like calcium and magnesium to strengthen the stems.

While some gardeners prefer bulb fertilizers, slow-release granular organic fertilizers generally yield better results. Options like Flower-Tone or Jobe’s Organics Annuals & Perennials, which are certified by the Organic Materials Review Institute (OMRI), provide a great organic alternative to synthetic chemical fertilizers.

Water-soluble fertilizers such as liquid kelp or general all-purpose liquid fertilizers are viable alternatives. However, they require more frequent application as their nutrients are available for only a short period. These types of fertilizers are better suited for annual plants rather than perennials like peonies. For peonies, slow-release granular fertilizers that provide nutrients over weeks are the optimal choice.

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Achieving the Ideal NPK Ratio for Peonies

When selecting a granular fertilizer for peonies, it’s essential to consider the NPK ratio. Nitrogen (N) promotes leafy growth, phosphorus (P) supports root development and healthy flowers, and potassium (K) enhances overall plant vigor. For peonies, it’s best to choose a fertilizer with slightly less nitrogen than phosphorus and potassium. This ratio encourages robust root and bloom growth, rather than excessive foliage. An ideal NPK ratio for peonies falls within ranges like 3-4-5, 3-5-5, 2-5-4, or similar compositions. Lower numbers typically denote organic fertilizers that release nutrients gradually, while higher numbers can potentially burn foliage, especially delicate emerging peony shoots.

Amount and Application Guidelines

The amount of fertilizer to apply depends on factors like the brand and type of fertilizer. As a general guideline, herbaceous peonies benefit from around ¼ cup of granular organic peony fertilizer per year, while tree peonies can receive up to ½ cup. If the plant is under two years old, 2 tablespoons will suffice. In case of uncertainty, it’s better to err on the side of caution and apply less fertilizer to avoid potential burn on stems or roots, excessive top growth, and wastage of resources.

To apply slow-release fertilizers, sprinkle them in a circular pattern around the crown of the plant. Maintain a distance of 3 to 4 inches from the base of the peony stems to prevent foliage or stem burn. Afterward, gently mix the granules into the soil by scratching them to a depth of 1 to 2 inches using a cultivator or trowel.

Bone Meal as a Boost for Peonies

For an additional nutritional boost at the end of the growing season, consider using bone meal. Bone meal is a valuable phosphorus source, vital for root and flower development. It takes a few weeks to a few months for bone meal to release its phosphorus, as soil microbes must process it first. Applying bone meal in the fall ensures that the added phosphorus becomes available for plant use by the following spring. However, it is important to note that excessive phosphorus can be harmful, and many soils already contain sufficient amounts. Before adding bone meal, it is advisable to conduct a soil test to determine the phosphorus levels in your soil.

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Fertilizing Peonies during Planting

Bone meal is an excellent choice for new peony plants at the time of planting. It promotes robust root development during the initial growth years without harming new roots when mixed into the soil. A quarter cup of bone meal per plant is sufficient.

Considerations for Fertilizing Peonies

Here are a few additional points to remember when fertilizing peonies:

  • Avoid excessive nitrogen, as it can have adverse effects. Select your peony fertilizer carefully, choosing products with lower nitrogen content.
  • Organic fertilizers release nutrients when moisture is present. Ensure that you water the plants after applying organic fertilizers and maintain adequate moisture levels during dry periods.
  • Manure is not recommended for peonies, as it typically contains excessive nitrogen, which can result in weak stems and fewer blooms.
  • Regularly remove spent flowers to prevent seed formation, allowing the plant to focus its energy on growing bigger and more robust roots for increased blooms in the next season.

Revel in the Power of Peonies

Peonies add beauty and charm to any garden, and with proper care, they can thrive for generations. By following the fertilization guidelines outlined in this article, you can ensure that your peonies grace your garden with sturdier stems and more spectacular blooms. For more information on caring for perennials, visit Ames Farm Center.