Why is my rhubarb not red enough?

Why is some rhubarb pale and not red?

Rhubarb is actually a crop you can "train" to color. There are two types of rhubarb stalks in appearance: green/yellow ones that stay pale forever, and red varieties that can become intensely red. But even red rhubarb varieties can underperform in color if conditions are wrong.

Rhubarb forms a thick underground rootstock (rhizome) where all first-year energy goes. From year two onward, leaves grow and the plant matures. The red color in rhubarb stalks is present in some cells, especially beneath the surface. But those red pigments (anthocyanins) only fully activate under certain conditions.

For red stalks you need: (1) the correct varieties, (2) lots of direct sunlight, (3) cooler nights, and (4) a mature plant with large root reserves.

Which rhubarb varieties are truly red?

This is the first step. Not all rhubarb varieties have red potential - some are genetically always green/yellow. Make sure you have planted a truly red variety.

Green/yellow varieties (stay pale):

• Glaskin's Perpetual (English green, dusted white)
• Victoria (big English variety, mostly green)
• Early Prolific (old British variety, little color)

Red and pink varieties (good red potential):

• Timperley Early (English heritage, bright red)
• Champagne (pink-red, good for preserves)
• Valentine (deep red, beautiful color)
• Stockbridge Arrow (very red English variety)
• Fulton's Strawberry (deepens to rich red)

Check your plant. What did you actually plant? Some garden shops accidentally sell green varieties under a generic "rhubarb" name. Check the plant label or seed packet. "Red" in the name is usually a good sign.

Insufficient sunlight

The second factor is sunlight. Rhubarb does grow in partial shade, but for red color you need at least 6-8 hours of direct sun daily. Less sun equals fewer red anthocyanins in the stalk.

Check your planting spot. Shade from trees, sheds, or houses? This is the problem. Rhubarb stalks that grow mostly in shade turn green or pale yellow, even if the variety could be red.

Light problem: you cannot do much without moving the plant (you can, but wait until autumn). Plan for next season: place red rhubarb varieties in the sunniest garden spot.

Temperature during growing season

Rhubarb loves cooler conditions. Red color development happens faster at 12-18 degrees Celsius. In warm summers (above 22 degrees), rhubarb grows faster but produces less red color. This is counter-intuitive, but it is true.

This is why English rhubarb (originally from cool climates) is so red: the growing period in England is cool and moist. Rhubarb in warm, dry regions tends to stay greener.

This is hard to adjust unless you place a shade cloth in May-June to keep the plant slightly cooler. It is not standard advice.

Insufficient maturity/root reserves

Rhubarb in year 1 after planting is still very small and weak. Roots only build up in years 2-3. A young plant cannot produce much red color because all energy goes into root growth.

If your rhubarb is only 1-2 years old, it is normal that it is still pale red. Wait until year 3-4. Then you have a strong plant with large reserves and stalks will be much redder.

This takes patience.

Harvest method

The way you harvest rhubarb matters too. If you start too early in the season (March) the first stalks are always paler than later ones (May-June stalks). This is normal.

Also: if you "force" rhubarb (meaning you exclude light over winter for early harvest), those stalks intentionally become pale. This is the intention - you get blanched (white) rhubarb.

Normal harvest (without forcing) in May-June gives red stalks. Harvesting in March-April gives still somewhat paler stalks.

When should you harvest rhubarb for best color?

Start your harvest in May. The first couple of weeks of May already give red stalks if conditions are right. June-July is peak season for rhubarb color - deep red intense. After early July, rhubarb grows less and stalks become slightly stringy, so stop harvesting.

Always harvest fully mature stalks. Cut them at the base (do not pull) so you do not leave a wound in the rhizome.

Step-by-step

Step 1: Check your varieties

Make sure you have actually planted a red variety: Timperley Early, Valentine, Stockbridge Arrow or similar. Green varieties will not turn red.

Step 2: Move to sunlight

Replant your rhubarb to a spot with at least 6-8 hours of direct sun. This is not urgent - autumn/winter is best for moving.

Step 3: Wait for maturity

Is your plant still young (year 1-2)? Wait until year 3-4. Rhubarb builds roots first. You see truly red color only with a mature plant.

Step 4: Harvest at the right time

Start your harvest in May (not March). Harvest until early July. The long warm days of June give the reddest stalks.

Frequently asked questions

Can I turn green rhubarb red with fertilizer?

No. Fertilizer helps growth, not color. Red color is genetic and environmental. Green variety stays green.

How much sun does rhubarb really need?

At least 6 hours of direct sun. Preferably 8 hours. Full sun (10+ hours) is fine.

Can I harvest rhubarb in the first year?

No. Start harvesting in year 2, and carefully. Let the plant put energy into roots.

Is "forced" rhubarb worse than normal?

No, different. Forced rhubarb is intentionally pale (white/light pink) because you exclude light. This is for delicate flavor. Normally grown rhubarb is stronger in taste and more intensely red.

How many stalks can I harvest per plant?

Harvest a maximum of 50% of available stalks at a time. Always leave at least 3-4 leaves to keep photosynthesis working. Over-harvesting weakens the plant.

Why does rhubarb get fibrous/stringy?

This is texture not color. Young stalks are smooth. Old stalks (harvested after early July) become more fibrous. This is normal aging, not bad.

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