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Best Fertilizer for Rhubarb: Rhubarb Fertilization 101

Unlock the secrets of successful rhubarb cultivation with our comprehensive guide on the best fertilizer for rhubarb. Discover the optimal fertilizer choices, delve into effective rhubarb fertilization techniques, and explore essential rhubarb growing tips. Our in-depth insights cover organic rhubarb fertilization, emphasizing soil nutrition for thriving plants.

Best Fertilizer for Rhubarb

Unveil the top-rated fertilizers tailored to enhance rhubarb plant care, ensuring robust growth and bountiful yields. Fertilizing rhubarb plants becomes a precise science with our Rhubarb Fertilization 101, providing a roadmap to elevate your rhubarb garden.

Introduction to Rhubarb and Its Nutritional Needs

Rhubarb is a perennial vegetable that produces edible leaf stalks that are often used in pies, jams, and other desserts. Rhubarb is easy to grow and can produce a harvest for many years if cared for properly. However, rhubarb also has a high demand for nutrients, especially nitrogen, phosphorus, and potassium. These nutrients are essential for the growth, development, and quality of the rhubarb stalks. Therefore, fertilizing rhubarb is an important part of its cultivation.

How and When to Fertilize Rhubarb

Choosing the Right Fertilizer

There are many types of fertilizers available for rhubarb, but not all of them are suitable or beneficial. The best fertilizers for rhubarb are those balanced ratio of nitrogen, phosphorus, and potassium, such as 10-10-10 or 25-3-3. These fertilizers can be organic or inorganic, depending on your preference and availability. Organic fertilizers are obtained from natural sources, such as compost, manure, or blood meal. They are usually slow-release and improve the soil structure and health. Inorganic fertilizers are synthetic chemicals that provide quick and precise amounts of nutrients.

Timing of Fertilization

The best time to fertilize rhubarb is in early spring before the growth starts and again in late summer or early fall after the harvest is over. The spring fertilization provides the nutrients needed for the development of the stalks, while the fall fertilization helps the plant store energy for the winter dormancy.

Application Methods

Apply fertilizer to rhubarb, depending on the type of fertilizer you choose. For organic fertilizers, like compost or manure, you can spread a layer of about 2 inches thick near the base of each plant, avoiding direct contact with the stems or leaves. For inorganic fertilizers, such as granular or liquid forms, you can sprinkle or spray them evenly over the soil surface around each plant, following the label instructions for the dosage and frequency.

Dosage and Frequency

Apply about half a cup of nitrogen-rich fertilizer per plant in spring and about a quarter cup of phosphorus-rich fertilizer per plant in fall. However, you should always adjust your fertilizer application according to your soil test results, your plant performance, and your harvest goals.

Best Fertilizer for Rhubarb

Organic Fertilizers for Rhubarb

Organic fertilizers are a popular choice for rhubarb cultivation due to their natural and sustainable benefits. A balanced mix of nutrients, organic matter, microorganisms, and humus, which can be made from kitchen scraps, yard waste, or animal manure. Compost, another organic fertilizer, is a good choice as it can be applied to rhubarb in spring and fall as a mulch or soil amendment. 

Manure, another excellent organic fertilizer, is rich in nitrogen, phosphorus, potassium, and other trace elements. It can be obtained from various animals but should be used well-rotted or aged to avoid burning roots or introducing pathogens or weeds. Blood meal, a by-product of the slaughter industry, is rich in nitrogen and can boost rhubarb stalk growth and color, as well as deter pests like deer or rabbits. It can be applied to rhubarb in spring as a top dressing or a side dressing.

Inorganic Fertilizers for Rhubarb

Inorganic fertilizers are popular among gardeners for rhubarb cultivation due to their precise and consistent nutrient amounts. These fertilizers are easy to apply and store, making them suitable for both spring and fall plantings. Some common inorganic fertilizers include 10-10-10, which provides equal amounts of nitrogen, phosphorus, and potassium, and 25-3-3, which stimulates growth and yield in rhubarb stalks. 

The dosage and frequency should be followed by the plant, with a general guideline of applying about 1 ounce per plant in spring. Lastly, 0-20-20, a high-phosphorus and high-potassium fertilizer, can enhance root development and winter hardiness in rhubarb plants. The general guideline is to apply about 1 ounce per plant in the fall, following the label instructions for dosage and frequency.

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rhubarb plant growing in the garden

Soil pH and Rhubarb Fertilization

Soil pH is determining the availability and uptake of nutrients by plants. Rhubarb thrives in slightly acidic to neutral soil pH levels of 6.0 to 6.8, which can be adjusted before planting or fertilizing. To lower pH, add sulfur, peat moss, or pine needles, while to raise it, add lime, wood ash, or crushed eggshells. Always test soil pH before making any amendments and follow recommended application amounts and frequency.

Rhubarb Fertilization and Watering

Rhubarb plants require regular and deep watering, especially during dry spells or hot weather, to maintain their growth and quality. They can tolerate drought but produce smaller, tougher stalks if stressed. Watering should be done once or twice a week, depending on weather and soil conditions, ensuring the water reaches at least 6 inches below the soil surface.

Avoid watering too frequently or too lightly to prevent shallow rooting or root rot. Watering also influences the effectiveness of fertilization, so it’s crucial to water rhubarb plants well after applying fertilizer to help them dissolve and distribute into the soil. Avoid applying fertilizer when the soil is too wet or too dry.

Rhubarb Fertilization and Pest Management

Rhubarb plants require a significant amount of nutrients, particularly nitrogen (N), for optimal growth. Fertilizing them every spring and after harvest is crucial for their recovery. Organic or mineral fertilizers can be used, but it’s important not to over-fertilize or damage the roots. Organic matter can also be used to maintain soil moisture and prevent weeds. 

Rhubarb can be affected by pests and diseases like slugs, snails, aphids, and more. Regular inspections and removal of infected or damaged parts can help control these issues. Natural methods like traps, barriers, diatomite, neem oil, insecticidal soap, and fungicides can also be used to control pests and diseases.

Common Mistakes to Avoid in Fertilizing Rhubarb

Common mistakes in rhubarb fertilization include applying too much or too little fertilizer, which can burn roots or cause excessive leaf growth, while too little can result in poor growth and low yield. To avoid these issues, follow the recommended rates and timings for your soil type and plant variety. Additionally, use fresh manure or compost that has not been rotted or deposited, as it can contain harmful pathogens or weed seeds that can infect or compete with rhubarb plants. Instead, use well-rotted or deposited manure or compost aged for at least six months.

Rhubarb Growth Techniques

  • Rhubarb thrives in cool climates, requiring winter dormancy, making full sun or partial shade with good drainage essential.
  • Avoid planting in areas recently used for growing other vegetables to prevent soil nutrient depletion.
  • Growth from seeds, crowns, or divisions: seeds are cost-effective but slower, while crowns and divisions offer quicker results.
  • Plant crowns or divisions in moist, unfrozen soil during early spring or fall, ensuring proper spacing and watering.
  • No harvesting in the first year, limited harvest in the second, gradually increasing in subsequent years.
  • Harvest stalks over 10 inches with red or green color; leave some for photosynthesis and energy storage.
  • Cease harvesting by June, remove flower stalks, cut and compost leaves, and protect from frost with organic materials.

Best Fertilizer for Rhubarb In a Nutshell

Common QuestionsExpert Answers
What kind of fertilizer is best for rhubarb?A balanced, general-purpose garden fertilizer, ideally with an NPK ratio close to 10-10-10, is often recommended for rhubarb. Organic options like compost, cow manure, and chicken manure are also beneficial.
Is urea good for rhubarb?Urea, a high-nitrogen fertilizer, can be beneficial as rhubarb likes nitrogen-rich soils, but it should be used in moderation to avoid over-fertilization.
Does rhubarb like high nitrogen?Yes, rhubarb benefits from nitrogen-rich soils, especially during the growth phase in spring.
What pH does rhubarb prefer?Rhubarb prefers slightly acidic to neutral soil, with a pH range of 6.0 to 6.8.
Are eggshells good for rhubarb plants?Eggshells can be beneficial as they add calcium to the soil, but they should be used as a supplement to a more comprehensive fertilization strategy.
What chemical makes rhubarb red?Anthocyanins, a type of flavonoid, are responsible for the red color in rhubarb stalks. This is influenced more by variety and growing conditions than fertilizer.
Is Epsom salt good for rhubarb plants?Epsom salt can be beneficial as it provides magnesium and sulfur, but it should not be the primary fertilizer.
What and when to fertilize rhubarb?Fertilize rhubarb in early spring and again in mid-summer with a balanced fertilizer. Avoid fertilizing in the fall as the plant needs to enter dormancy.
What is the best homemade rhubarb fertilizer?Compost and well-rotted manure are excellent homemade fertilizers for rhubarb, providing a balanced nutrient profile.
Can I fertilize rhubarb in the fall?It’s best to avoid fertilizing rhubarb in the fall since the plant needs to prepare for dormancy.
Is tomato food good for rhubarb?Tomato food, while typically higher in potassium, can be used but might not be ideal compared to a more balanced fertilizer.
Is bone meal good for rhubarb?Bone meal is beneficial for its phosphorus content, but it should be used as part of a balanced fertilization approach.
Does rhubarb need potash?Yes, potash (potassium) is important for overall plant health and can improve stalk quality.
How much fertilizer does rhubarb need?It is better to apply fertilizer according to package instructions, usually a few tablespoons per plant in the spring and again in mid-summer.
Why do rhubarb leaves turn yellow?Yellow leaves can be due to several reasons, including nutrient deficiencies, over-watering, or disease.
Does rhubarb like wood ash?Wood ash can be beneficial as it adds potassium, but use it sparingly due to its high alkalinity.
How often should I fertilize my rhubarb plants?Twice a year: in early spring to encourage growth, and again in mid-summer after harvesting.
Can I use organic fertilizer for rhubarb?Yes, organic fertilizers like compost, manures, and bone meal are excellent for rhubarb.
What are the ideal NPK ratios for rhubarb fertilizer?A balanced NPK ratio, such as 10-10-10, is typically recommended for rhubarb.
Should I fertilize rhubarb in the fall or spring?Fertilize in the spring and avoid fall fertilization to allow the plant to enter dormancy.
Can I use a general-purpose garden fertilizer for rhubarb?Yes, a general-purpose garden fertilizer is suitable for rhubarb.
How does fertilizer affect rhubarb growth and flavor?Proper fertilization promotes healthier growth and can enhance the flavor and color of the stalks.
Are there any natural fertilizers recommended for rhubarb?Compost, well-rotted manure, and bone meal are excellent natural fertilizers for rhubarb.
How to properly apply fertilizer to rhubarb plants?You cam apply fertilizer around the base of the plant, avoiding direct contact with the stalks and leaves, and water well.
Can over-fertilizing harm rhubarb plants?Yes, over-fertilizing can lead to excessive leaf growth at the expense of the stalks and potentially damage the plant.
Are there any specific micronutrients important for rhubarb?Micronutrients like magnesium and sulfur, found in Epsom salts, can be beneficial.
What is the best time of year to fertilize rhubarb?Early spring and midsummer are the best times to fertilize rhubarb.
Are chemical fertilizers safe for rhubarb, or should I stick to organic?Both chemical and organic fertilizers can be safe if used correctly, but organic is often preferred for edible plants.
Should I fertilize rhubarb during flowering or fruiting stages?Rhubarb should be fertilized during its growth stages in spring and post-harvest, not specifically during flowering.
How do soil pH levels affect fertilizer choice for rhubarb?Soil pH affects nutrient availability, so it’s important to choose a fertilizer that is suitable for slightly acidic to neutral soil pH.
Can coffee grounds be used as a fertilizer for rhubarb?Coffee grounds can be used as a mild fertilizer, providing nitrogen and lowering soil pH slightly.
Is it necessary to fertilize young rhubarb plants differently?Young plants benefit from a gentle, balanced fertilizer to encourage healthy root and leaf development.
What are the benefits of seaweed fertilizer for rhubarb?Seaweed fertilizer provides trace elements and can stimulate growth and root development.
How does potassium affect the growth of rhubarb plants?Potassium is important for overall plant health, root development, and can improve the quality of the stalks.
Can I use chicken manure as a fertilizer for rhubarb?Yes, chicken manure is an excellent organic fertilizer for rhubarb, providing a good balance of nutrients.
Are there any fertilizers to avoid when growing rhubarb?Avoid high-nitrogen fertilizers late in the season and fertilizers with high salt content that can damage the roots.
How do different types of fertilizers impact rhubarb stalk color?Fertilizer type generally doesn’t affect stalk color, which is more influenced by variety and temperature.
Is it beneficial to use slow-release fertilizer for rhubarb?Slow-release fertilizers provide a steady supply of nutrients, which can be beneficial for consistent growth.

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Rhubarb plants


Rhubarb is a delicious vegetable that can be enjoyed in many ways. However, to grow healthy and productive rhubarb plants, you need to fertilize and protect them from pests and diseases. You also need to follow some basic techniques for planting, harvesting, and overwintering your rhubarb plants. By following these tips, you can enjoy a rich harvest of rhubarb for many years to come.


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