Rhubarb plants respond best when they are fertilized with 10-10-10 fertilizer or a combination of composted manure and phosphorus. While 10-10-10 fertilizer is a great choice, if you want to follow an all-natural gardening plan, the compost-and-phosphorus method is the organic choice for rhubarb. Rhubarb does best when fertilized 2 times per year, once in spring and once in fall.
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Does Rhubarb Need Fertilizer?
In order to get the most yield out of your rhubarb plants, fertilize them twice per year. Without these fertilizer applications, your rhubarb will struggle, grow thinly, and won’t give you a good crop. Rhubarb may even die without enough fertilizer.
When Should You Fertilize Rhubarb?
Rhubarb is a perennial plant, meaning it will survive in your garden for many years. Because it is long-lived, rhubarb needs fertilizer in spring and fall. In comparison, annual vegetables typically only need fertilizer in spring. So, cultivating a rhubarb patch requires twice as much fertilizer as annual vegetables.
Should You Fertilize Rhubarb in the Spring?
Fertilize rhubarb plants first in early spring, in March or April. This timing will introduce organic matter at the soil surface. As you water your rhubarb, the fertilizer will be pulled deep down into the soil. This will feed the rhubarb crowns and roots, resulting in a large crop of rhubarb stalks.
Should You Fertilize Rhubarb More than Once Per-Year?
In addition to your spring fertilizer application, fertilize rhubarb again in the fall. This should be done in September or October when your rhubarb crowns have stopped producing new stalks. Spread the fertilizer 4 weeks before the first average fall frost. This allows the plant to take in the fertilizer nutrients and strengthen itself before winter. The result will be a stronger plant next spring.
What Fertilizer Should You Use for Rhubarb
Rhubarb is easy to grow and responds to simple fertilizers. Although rhubarb plants are heavy feeders, they will thrive in well-drained soil with ample fertilizer. Below we’ll cover the balanced fertilizer method, using 10-10-10 fertilizer. Then, we’ll walk through the process of using phosphorus and well-rotted manure compost for rhubarb.
Balanced Fertilizer Method
Beginning gardeners will have great results growing rhubarb using a balanced vegetable fertilizer. In order to use this method:
- Use this 10-10-10 fertilizer.
- Spread ½ cup of fertilizer granules on the ground in a circle around each rhubarb plant.
- Optionally, instead of fertilizing individual plants, spread 1.5 pounds of fertilizer for every 100 square feet of garden area.
- Water the ground until the soil is moist and the granules have begun to break down.
This simple process is all it takes to fertilize your rhubarb. Just perform this twice per year—in spring and fall—to ensure you have thriving rhubarb for years.
Organic Fertilizer Method
If you’d like to avoid using synthetic fertilizer for your rhubarb, you can grow it using organic compost and phosphorus. To follow this organic method:
- Wait until rhubarb shoots begin to grow in spring.
- Spread 2–3 inches of compost or rotted manure in a 12 inch diameter around each rhubarb plant.
- Spread 1–2 ounces of this superphosphate on the ground around each rhubarb plant.
- Keep the soil moist with water.
This natural method will keep your rhubarb growing well through harvest season and beyond. Just make sure to use true manure compost, not raw manure. Compost heats up during decomposition, which destroys harmful bacteria. Animal manure, however, contains harmful bacteria. Compost is a great fertilizer, while plain manure is dangerous and unhealthy to use.
Is Miracle Grow Good for Rhubarb?
Miracle-Gro is not a balanced fertilizer. 10-10-10 fertilizer contains equal amounts of nitrogen, phosphorus, and potassium. Miracle-Gro, on the other hand, is high in nitrogen and potassium but contains relatively little phosphorus. While this is good for some flowers, it is not ideal for a perennial vegetable such as rhubarb. Use a specifically designed vegetable fertilizer for your rhubarb.
When Should You Not Fertilize Rhubarb?
Do not fertilize rhubarb during its first year of growth. Although mature plants receive a lot of benefits from fertilizer, young plants don’t need it since they aren’t being harvested for food. As long as your soil is healthy and you provide plenty of water, you don’t need to fertilize your rhubarb until after it survives its first winter.
What is the Best Fertilizer to Use on Rhubarb?
In order to feed rhubarb roots and encourage a large crop of rhubarb leaves and stalks, use one of the following fertilizer methods:
- Method 1: Spread ½ cup of 10-10-10 fertilizer around each rhubarb plant, once in spring and once in fall.
- Method 2 (Organic Method): Spread 2–3 inches of composted manure around the base of each rhubarb plant, followed by 1–2 ounces of 46% phosphorus. Do this in both spring and fall.
These methods are both extremely effective and will work for all rhubarb varieties. Because it is a relatively easy plant to grow, using either of these fertilizer tactics will ensure you have many stalks of rhubarb at harvest time.