Fertilizing Black-Eyed Susan – Should you?

Rudbeckia, also known as Black-Eyed Susan, is a popular perennial plant that adds a vibrant touch to any garden with its bright yellow and orange flowers. These low-maintenance plants are known for their hardiness and ability to attract pollinators, making them perfect for both novice and experienced gardeners.

In order to help your Rudbeckia thrive, it’s essential to fertilize them correctly, ensuring they receive the necessary nutrients throughout the growing season.

When it comes to fertilizing Rudbeckia, it’s all about understanding their specific needs and using the appropriate products. Successful fertilization involves paying close attention to the type of fertilizer, the timing of application, and the overall health of the soil.

By adopting an effective fertilization routine tailored to your Rudbeckia, you can ensure these gorgeous flowers reach their full potential and bring beauty to your outdoor space for years to come.

In this article, we’ll discuss essential tips for fertilizing Rudbeckia that will help you maximize their growth, enhance their vibrant hues, and keep them strong and healthy.

Whether you’re a first-time planter or a seasoned gardener, these guidelines can lead you towards a flourishing and visually-appealing Rudbeckia garden.

Fundamental Basics

Rudbeckia, also known as black-eyed Susans and coneflowers, are popular, low-maintenance perennials known for their vibrant, daisy-like blooms. Proper fertilization is essential to ensure your rudbeckia plants grow healthy and produce abundant flowers. Here are some fundamental basics for fertilizing your rudbeckia plants.

First and foremost, it is essential to analyze your soil before applying any fertilizer. A simple soil test can help determine the nutrient levels and pH balance in your garden. Rudbeckia prefers well-draining soil with a pH between 6.0 and 7.0. If your soil pH is outside of this range, you’ll need to amend it before fertilizing.

Next, choose a balanced fertilizer for your rudbeckias. A slow-release, granular fertilizer with an even NPK ratio, such as 10-10-10, will provide your plants with the essential nutrients they need throughout the season. It’s a good idea to apply the fertilizer in early spring before the growing season begins.

When it comes to application rates, follow the specific recommendations on the fertilizer package. Over-fertilizing can lead to excessive growth and weak, leggy plants, while under-fertilizing may result in poor bloom production. As a general guideline, you can apply 1 to 2 tablespoons of the slow-release granular fertilizer per square foot of planted area.

Water your rudbeckia plants well after fertilizing to help distribute the nutrients throughout the soil. Always water at the base of the plant, avoiding wetting the leaves, as this can lead to disease issues.

Lastly, remember to practice proper maintenance of your rudbeckias to encourage healthy growth. This includes regular watering, deadheading spent blooms, and providing the appropriate amount of sunlight (full sun is best). With proper care and nourishment, your rudbeckia plants will reward you with stunning blooms year after year.

Ideal Time for Fertilizing

Rudbeckia, also known as Black-eyed Susan, is a charming and low-maintenance perennial plant that adds a burst of sunshine to any garden. To keep your Rudbeckia blooming abundantly and looking its best, proper fertilizing is essential. In this section, we’ll discuss the ideal time for fertilizing your Rudbeckia plants.

Early spring is a fantastic time to begin the fertilizing process. As the soil warms up and the plants begin to emerge from dormancy, providing them with a slow-release fertilizer can promote healthy growth and a strong root system. A balanced 10-10-10 fertilizer works well for Rudbeckia, as it provides equal amounts of nitrogen, phosphorus, and potassium to support overall plant health.

In addition to this initial spring feeding, it’s wise to give your Rudbeckia a boost of nutrients in the summer. Approximately halfway through the growing season, which often falls around mid-July, apply a side dressing of organic compost or a water-soluble fertilizer. This step ensures that your plants have adequate nutrients to sustain their blooms and vigor throughout the summer months.

Finally, as the fall approaches and your Rudbeckia plants prepare for winter dormancy, it’s essential to give them one last feeding to help build energy reserves for the following year. In late September or early October, apply a balanced, granular fertilizer around the base of the plants but be careful not to overfeed, which can lead to excessive growth and weak stems.

By fertilizing your Rudbeckia plants at these key stages of the growing season, you’ll encourage strong growth, beautiful blooms, and overall plant health. Remember to always follow the manufacturer’s instructions on your chosen fertilizer, ensuring you give the right amount at the correct times. Happy gardening!

Prepping Your Garden

Before you begin fertilizing rudbeckia, it’s essential to prepare the garden properly. Taking a little time to create an ideal environment for these vibrant flowers will pay off in healthier, more robust blooms.

First, you’ll want to find a sunny spot in your garden. Rudbeckias thrive in well-drained soil and prefer at least six hours of direct sunlight daily. Ensure that the space you choose gets enough light, as this will play a significant role in their growth.

Next, take the time to test your soil’s pH level. Rudbeckias grow best in soil with a pH ranging from 5.8 to 6.5, meaning they prefer a slightly acidic environment. You can purchase a soil testing kit at most gardening stores or online. If your soil falls outside of this range, consider adding sulfur or limestone to balance the pH level.

Once you’ve determined the ideal location and ensured that your soil’s pH is appropriate, it’s time to prepare the ground. Begin by loosening the soil using a fork or tiller. Aim for a depth of at least 8 inches, as this will promote a healthy root system.

Now it’s time to amend the soil with organic matter. Adding compost, aged manure, or leaf mold will improve soil structure and provide essential nutrients that will benefit your rudbeckia. Working one to two inches of organic matter into the planting area is recommended for best results.

By taking these crucial steps to prepare your garden before fertilizing rudbeckia, you’ll create an optimal environment for these blooms to flourish and showcase their full potential. With the right preparation, your stunning rudbeckias will be the talk of the neighborhood.

Choosing the Right Fertilizer

When fertilizing your Rudbeckia plants, you can choose between organic or chemical options, depending on the type of nutrients and environment you want to cultivate. Both options provide different benefits and have different application processes.

Organic Options

Compost is an excellent organic option for providing essential nutrients to your Rudbeckia plants. You can mix well-decomposed compost with the soil before planting or use it as a top dressing during the growing season.

  • Advantages: improves soil structure, adds beneficial microorganisms, environmentally friendly.
  • How to use: Apply 1-2 inches of compost around the base of your plants.

Animal manure can be a great source of nutrients as well, with aged cow or horse manure being the most popular.

  • Advantages: adds nitrogen, phosphorus, and potassium to the soil, promotes healthy plant growth.
  • How to use: Incorporate well-rotted manure into the soil a few weeks before planting.

Fish emulsion or seaweed extract can also serve as organic fertilizers for Rudbeckia plants.

  • Advantages: provides essential nutrients and trace elements, easily absorbed by plants.
  • How to use: Dilute the extract according to the package instructions and apply it with a watering can.

Chemical Options

Slow-release fertilizer can be an efficient choice for providing a steady supply of nutrients to your Rudbeckia plants.

  • Advantages: gradually releases nutrients, reducing the risk of overfertilization, easy to apply.
  • How to use: Apply the fertilizer granules a few inches from the plant base according to the product label.

Water-soluble fertilizer is another option for quick and effective results.

  • Advantages: fast-acting, allows for control over application.
  • How to use: Dilute the fertilizer in water according to package instructions and apply to the soil around the plants every couple of weeks during the growing season.

Remember that Rudbeckias are relatively low-maintenance, and they don’t require heavy fertilization. Make sure to follow the recommendations for each fertilizer type to ensure a healthy, vibrant growth of your Rudbeckia plants.

Fertilizing Techniques

Rudbeckia plants, also known as black-eyed Susans, are low-maintenance perennials that benefit from proper fertilization techniques. In this section, we will discuss Broadcast Method and Side-Dressing Method to help you achieve optimal growth and blooming for your Rudbeckia plants.

Broadcast Method

The Broadcast Method is an efficient way to apply fertilizer evenly across your garden bed. This technique works well for large gardens with multiple Rudbeckia plants. To use the broadcast method:

  1. Measure the recommended amount of fertilizer according to the package instructions, based on the size of your garden.
  2. Scatter the fertilizer evenly across your garden bed, ensuring the granules do not bunch up in one location.
  3. Water your garden thoroughly following the fertilizer application to help the nutrients penetrate the soil.

This method helps ensure a uniform distribution of nutrients, promoting consistent growth of your Rudbeckia plants.

Side-Dressing Method

The Side-Dressing Method is a more targeted approach to fertilizing your Rudbeckia plants, focusing on feeding individual plants. This technique is suitable for smaller gardens or potted plants. To use the side-dressing method:

  1. Create a small trench around the base of your Rudbeckia plant, roughly 3 to 4 inches away from the stem.
  2. Measure the appropriate amount of fertilizer based on the size and age of your plant, following the package instructions.
  3. Sprinkle the fertilizer along the trench you created, avoiding direct contact with the plant stem.
  4. Cover the trench with soil and water the plant thoroughly.

This method allows you to deliver nutrients directly to the plant’s roots for targeted growth.

Keeping these fertilizing techniques in mind, you will be able to provide a nutrient-rich environment for your Rudbeckia plants to thrive and bloom beautifully.

Maintenance and Care

Watering After Fertilizing

It’s essential to give your Rudbeckia adequate water after fertilizing. This not only helps the nutrients in the fertilizer to disperse evenly but also prevents potential root damage. It’s best to water your plants deeply, allowing the soil to become moist, but not saturated or flooded. A good rule of thumb to follow is to water your plants until the top 6 inches of soil are moistened. In most cases, this amounts to providing about 1 inch of water per week.

Monitoring Growth

Growth monitoring is an integral part of Rudbeckia care. Observing changes in your plant’s health and growth will enable you to spot issues, such as nutrient deficiencies or pests, early on.

Here are some key points to keep in mind while monitoring your Rudbeckia:

  • Check for signs of growth: Keep an eye on the appearance of new leaves, plant height, and stem thickness. Healthy Rudbeckia plants should have vibrant-colored leaves and a strong, sturdy stem.
  • Inspect the foliage: Look for any yellowing, wilting, curling, or spots on leaves, which could indicate a nutrient imbalance, pests, or disease.
  • Record your observations: Maintain a log or journal of your plant’s progress, including any changes you notice over time. This can help you spot patterns or identify specific issues with your plants.

Adhering to proper maintenance and care practices for your Rudbeckia plants will ensure beautiful blooms and a thriving garden. Remember to water consistently after fertilizing and be diligent in monitoring your plants’ growth for the best results.

Fertilizing Tips for Different Rudbeckia Varieties

Annual Types

Annual Rudbeckia varieties such as Rudbeckia hirta are generally low-maintenance and require minimal fertilization. When planting, it’s a good idea to mix in some well-rotted compost or slow-release granular fertilizer into the planting hole. This will provide essential nutrients for the plant and give it a head start.

After you’ve established your annual Rudbeckias, you can follow these simple fertilizing tips for healthy growth:

  • Apply a balanced, 10-10-10 fertilizer in early spring when new growth appears. This will help encourage robust flowering.
  • Be sure not to over-fertilize, as too much nitrogen can cause excessive foliage growth at the expense of blooms.

Perennial Types

Perennial Rudbeckia varieties, such as Rudbeckia fulgida and Rudbeckia triloba, are more robust and will benefit from a slightly different fertilizing regimen. Here are some tips to ensure healthy growth:

  • In the early spring, apply a balanced, slow-release, 10-10-10 fertilizer. You can either mix this into the top few inches of soil or apply it around the plant as a side dressing. This will help promote blooming and overall plant health.
  • You may want to apply a second, lighter dose of fertilizer in mid-summer, especially if you notice your Rudbeckias starting to decline in vigor.

Remember, it’s essential to not over-fertilize your plants – too much of a good thing can have negative consequences. A friendly rule of thumb is to always follow the recommended application rates provided on the fertilizer packaging.

Common Issues and Solutions


Over-fertilizing your Rudbeckia plants can have some unwanted side effects. If you notice your plants have yellowed leaves, weak stems, or a burnt appearance, this could be due to an excess of fertilizer. To mitigate this issue, follow these steps:

  1. Water thoroughly: Make sure to flush out the excess fertilizer by providing your plants with plenty of water. This will help dilute the concentration of nutrients in the soil.
  2. Reduce fertilizer use: Apply fertilizer in smaller amounts and less frequently to avoid over-fertilization in the future.

Nutrient Deficiencies

Rudbeckia plants can suffer from nutrient deficiencies that result in stunted growth, pale leaves, or slow flowering. The two most common deficiencies are:

  • Nitrogen deficiency: Symptoms include yellowing leaves and poor growth. To address this deficiency, try adding a nitrogen-rich organic fertilizer, such as blood meal or fish emulsion, to your soil.
  • Phosphorus deficiency: Signs of phosphorus deficiency include a purplish-red cast on leaves and weak root growth. To remedy this, apply a high-phosphorus fertilizer, such as bone meal or rock phosphate, to your soil.

Remember to always provide your Rudbeckia plants with the right balance of nutrients to support their healthy growth and development. Happy gardening!


Rudbeckia, also known as black-eyed Susan, is a popular, low-maintenance perennial that adds vibrant color to gardens and landscapes. The key to keeping these cheerful flowers healthy and vibrant is proper fertilization.

When fertilizing rudbeckia, it’s essential to use a balanced fertilizer with equal amounts of nitrogen, phosphorus, and potassium. This promotes overall plant health, including strong roots, foliage, and blossoms. Aim to fertilize in the early spring and again in mid-summer for the best results.

To properly apply fertilizer, follow these steps:

  • Measure the recommended amount of fertilizer for your plant size and type
  • Scatter the granules evenly around the base of the plant
  • Lightly scratch the fertilizer into the soil with a rake or your fingers
  • Water the area thoroughly to help the fertilizer dissolve and enter the root zone

In addition to using a commercial fertilizer, rudbeckia can also benefit from organic fertilizers such as compost or well-aged manure. These materials release nutrients slowly, aiding in the long-term health of your plants.

Remember that over-fertilizing can be harmful to your plants, so it’s crucial to follow the guidelines provided by the fertilizer manufacturer and resist the urge to give your rudbeckia too much of a good thing.

With proper fertilization and care, your rudbeckia will reward you with an abundance of beautiful blooms for years to come. So go ahead and add some color and charm to your garden by nurturing these stunning native flowers.