I will always say that the rhubarb I buy from my stand at the Saint-Malo farmers’ market is of higher quality, but I’ve never been happy with its color. The stalks, while reddish at the base are, and cook up, mostly green. This makes for some pretty ugly jams and compotes, because the green, cooked rhubarb is dun and pale. Not exactly appetizing. I’ve made up for it by adding strawberries, cherries, and even a splash of crème de cassis, but the truth is that rhubarb has turned green in my world.
From what I’ve learned, green rhubarb is not less good than red rhubarb (except for the color). Another thing I think I know about the color change: green varieties are tougher and usually grow better. This isn’t just my grower’s fault. Also, many of the early-harvest rhubarb varieties tend to be green. From my own experience, rhubarb that is green (almost) isn’t as stringy as some deep red rhubarb I’ve bought. Better quality, better yield, quicker to market…small wonder my vegetable grower has gone with a greener varietal.
Guess it’s time to embrace that my rhubarb recipes are—and perhaps always will be—a little green.
You excitedly planted red rhubarb varieties last season dreaming of crimson stalks for pies and jams. But when you harvest the stems are still mostly greenish or at best a dull bronze. What happened to that vibrant red color you expected?
It’s frustrating when rhubarb doesn’t develop the deep red hues you anticipated. But in many cases the cause is easily fixed. Here are some common reasons rhubarb stalks stay greenish along with solutions to help them turn red.
Insufficient Sunlight
Rhubarb needs full sun to produce the bright red pigments. At least 8-10 hours of direct sunlight daily is ideal. With insufficient light exposure, stems will be more green or bronze rather than red.
If possible, move rhubarb plants to the sunniest part of your yard. South or west facing locations are best. Ensure no buildings or trees shade the plants during peak daylight hours.
Low Soil pH
The soil pH around rhubarb plants directly impacts stem color. Rhubarb prefers a slightly acidic pH between 6.0-6.8. If pH creeps lower into the more acidic range, stalks turn green.
Over time, rhubarb debris lowers the soil pH. Test the pH around your plants. To raise pH, mix in dolomitic lime or crushed eggshells. Wood ash also quickly raises pH.
Plant Stress
Environmental stress like drought, overcrowding, pests, or diseases can inhibit full red pigment production. Healthy, vigorous plants have the resources to develop red stalks.
Eliminate sources of stress. Prune plants to reduce overcrowding. Water and fertilize appropriately. Check for signs of diseases or insects. Reduce stress for optimal health.
Age of Plants
As rhubarb plants age and lose vigor, the stalks may fade to green or bronze rather than remaining bright red. Older than 5 years, dividing clumps may help rejuvenate them.
If your plants are aging, divide the roots in early spring. Discard the oldest center portion and replant younger, more vigorous divisions.
Wrong Variety
Some rhubarb varieties have genetics that limit red pigment development. ‘Victoria’, ‘Valentine’, and ‘Chipman’s Canada Red’ are reliably red. ‘MacDonald’ and others tend greener.
Check what variety you planted. Heirlooms like ‘Cherry Red’ and ‘Sweet Cherry’ also produce excellent red stalks when conditions are right.
Solutions for Redder Rhubarb
Once you know the cause, here are some tips to improve red color:
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Move plants to the sunniest spot in your yard.
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Test and amend soil to reach the ideal slightly acidic pH.
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Ensure proper water, fertility, spacing, and reduce plant stress.
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Divide old plants or start new ones for greater vigor.
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Stick with red-stemmed rhubarb varieties rather than mostly green kinds.
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Cut off flower stalks to encourage red pigment in the leaves.
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Use black plastic mulch to warm the soil and boost redness.
With the right conditions, your rhubarb will live up to its red potential. Patience through the first year or two is needed, as stalks often start off green before full color develops. But with a little tweaking to care, sunlight, and soil, you’ll be rewarded with crimson red rhubarb stems perfect for baking.
Frequently Asked Questions About Rhubarb Color
Still puzzled about the lack of red color in your rhubarb? Here are answers to some other common questions.
Why is my rhubarb red on the bottom but green on top?
This is normal early in the season. The base of the stalk near the roots forms first and has time to develop red pigment. The newer top portion emerges green but should redden up as it grows.
I cut my rhubarb too early. Will it still turn red?
If harvested too soon, rhubarb stalks often stay all green. For full red color, wait until stalks are at least 1 inch wide before picking. The wider they grow, the redder they’ll be.
Do green and red rhubarb taste different?
Not necessarily. Some very green varieties like ‘Victoria’ are quite sweet. And some red kinds can be more tart or stringy. Color and flavor are separate traits. Both green and red rhubarb can taste delicious.
Does the flower stalk affect color?
Yes! The tall flower stalks that emerge in late summer divert energy from red stalk production. Always cut off flower stalks as soon as they appear to encourage red pigments.
How often should I divide old rhubarb roots?
For optimal growth and redness, divide congested rhubarb clumps every 5-8 years in early spring. This keeps plants vigorous and stimulates strong new red stems.
Why are the leaf stalks and leaves also red?
Some heirloom rhubarb varieties have genes that cause red pigments throughout the plant, creating red leaf stalks and red veining in leaves. This is normal for certain red varieties as the whole plant takes on red hues.
Turn Up the Red in Your Garden
With the right care tailored to their preferences, rhubarb can develop into a dramatic crimson focal point in your edible garden. Follow these tips to discover why your rhubarb isn’t turning red, then make adjustments to bring out that fantastic color you expected. Soon you’ll be harvesting vibrant red stalks for all your baking and cooking needs.