Feeding Rhubarb: When and What to Fertilize With

Rhubarb is easy to grow—but for those legendary thick, juicy stalks, it’s not enough to just plant and hope. Proper feeding is your secret weapon for bigger harvests, happy plants, and a patch that lasts for decades. Here’s when, what, and how to feed rhubarb for maximum results.

When to Feed Rhubarb

1. Early Spring—As Growth Begins

• This is the most important feeding window!
• Rhubarb “wakes up” hungry, so feed as soon as new leaves poke through the soil.

2. After Harvest (July–August)

• Light top-dressing after you finish major picking gives crowns what they need to recover and store energy for next year.

3. Autumn (Optional)

• Mulch with well-rotted compost or manure after the leaves die back for long-term soil improvement.

What Fertilizer Is Best for Rhubarb?

Organic Option – Best Choice

• Well-rotted manure or garden compost: Heap 5–8cm (2–3in) around crowns each spring, not touching the buds.
• Blood, fish, and bone or pelleted chicken manure: Sprinkle in early spring for balanced nutrition.

Balanced Fertilizer (If Needed)

• Slow-release granular or organic fertilizer (NPK 5-5-5 or 10-10-10).
• Sprinkle in a circle 15cm (6in) from the crown.

High-Potash Feed

• A light application of tomato food or wood ash can help stalks pick up sweetness and color.

Feeding Do’s and Don’ts

• DO mulch every spring—it feeds, retains water, and suppresses weeds.
• DO NOT feed with high-nitrogen fertilizers (like fresh manure or lawn feed): Too much nitrogen means lots of leaf, weak stalks, and rot.
• DO NOT heap compost directly over the crown—keep a 5cm (2in) clearance to prevent rot.

Feeding for Container-Grown Rhubarb

• Feed monthly with liquid seaweed or tomato fertilizer from spring to midsummer.
• Top-dress with compost or manure after every big harvest.

Signs Your Rhubarb Needs Feeding

• Spindly, thin, or short stalks.
• Yellowing leaves (but check watering/drainage too).
• Declining harvest from a previously reliable patch.

Wrapping Up

The secret to spectacular rhubarb? Rich compost, steady spring feeding, and NO overdoing it on the nitrogen. Nourish your roots with organic goodness, and your patch will thank you with a bounty of tart, delicious stalks spring after spring.