Hollow Rhubarb Stalks -7 Reasons & Control Measure

Rhubarbs are fresh and crispy vegetables with vivid red stalks highly used in culinary industries. These are mainly the plants of freezing temperatures. So, gardeners often suffer from different problems while growing them.

As the stalks are the only edible part in rhubarbs, I have picked one of the most common issues with these; the hollow stems. If you can relate to this, welcome! 

In this article, I’m going to highlight the facts: inadequate watering, improper soil and nutrition, crown rot, pest attack, and extreme temperatures. Keep reading to know how these affect your plant and what are the fixes.



Inadequate WateringWater once every 7 days to a depth of 2 to 5 cm.
Improper SoilMaintain the drainage and proper pH level in the soil.
Crown RotKeep the plant base dry and apply suitable fungicide.
Pest AttackUse baits, traps, or pesticides to control snails and slugs.
Nutrient DeficiencyApply organic composts or calcium-magnesium solutions.
Excessive NitrogenPick a balanced dose of fertilizer.
High TemperaturesUse mulches and provide necessary shadings.

 Why Are the Rhubarb Stalks Turning Hollow-Problems and Fixes

Rhubarb Stems

1. Inadequate Watering

Rhubarb stalks are thick, fleshy, and crispy with beautiful reddish hues. Water is the main component of the stalks which maintains their healthy appearance.

If there is a lack of water during the growing period of rhubarb it may lead to hollow and sick-looking stalks. Wilting is the primary sign of inadequate watering. You may notice droopy stems and leaves in your rhubarb at the initial stage.

Prompt actions and some management can save your rhubarb. Let’s see what you can do for your plant.


During the first year of growth, rhubarbs need water once every three days. When established, this water demand reduces to once per 7 days. 2 to 5 cm of watering is enough followed by the plant base soaking properly.

If you notice wilting symptoms, water deeply so that the roots can’t get enough water. But do not add too much water at once. Increase the amount of water with time.

In pot-planted rhubarbs, you can put a sink or bowl full of water and place your container into that. This will allow the roots to soak water gradually and efficiently with time. But do not practice this method for longer as it can increase the chance of root rotting.

It is suggested to provide some kind of shade after all these practices to protect your rhubarbs from direct sunlight for some time. You can make a tent out of dark plastic coverings to provide partial shading to your plants.

If possible you can use drip irrigation in your garden. This will save your plants during hot summer days.

2. Improper Soil

Rhubarbs prefer well-drained and fertile soil with a pH of 6.0 to 6.8. The edible stalks can be damaged severely due to compact and poor soils.

Improper soil conditions can affect the overall growth of rhubarb. Hollow stalks problems are closely related to this. Poor soils can also cause short stalks with big leaves in rhubarbs. So, you can trace soil issues by this.

It’s not that hard to deal with such soil conditions. Just follow my instructions to solve this.


Garden soils get compact with time which reduces drainage potential. To restore the drainage capability with better water holding capacity, organic matters work excellently.

You can add well decomposed organic manure or farm yard manure or even dry shredded leaves to improve soil texture. If your soil is too clayey, incorporate one-third of slits or sands in it. This will also promote better drainage.

Balancing the pH level is also important. To increase the pH level, add crushed limestone to your soil and to decrease the use of elemental sulfur or aluminum sulfate, or sulfuric acid. Special formulations are available in these. Use according to the instructions.

To maintain the soil texture and proper aeration, keep tossing the soil often. But be careful about not harming the roots and stalks.

3. Crown Rot

Rhubarb crowns are found at the underground level after one year of growth. Though it’s not any edible part, plants’ health and propagation are very much dependent on this. 

Fungal infestations and overwatering can cause rotting of this part. In rhubarb, crown rot is caused by a honey fungus which shows reddish spots on leaves at the initial stage. You may also notice the yellowing of foliage. Some of your stalks may look healthy but others, when cut open, look spongy and a zigzag growth pattern is observed that gradually promotes the hollow stalks.

So, if you are wondering why my rhubarb stalks are hollow even after all the good practices, crown rot can be the issue. Let’s check what you can do to deal with this.

Control Measure

Overwatering can promote root and crown rots in rhubarbs. So be careful about this. Follow the watering instructions I have mentioned before.

In the case of accidental overwatering, stop intense watering for at least 15 days and let your plant have some sun exposure to dry up the soil. If wilting is observed, you can sprinkle some water lightly near the plant base during this period. 

Now let’s come to the rotting issue. After the initial symptoms are noticed, it’s better to pull off and remove the affected stalk. This will prevent the spreading of fungal spores to other plants.

Do not let the soil be wet for a long time near the plant base. You can spread some ashes near your plant base. This will soak up the extra moisture. Keep changing the ashes and replace them with a new one every two days.

If the infection is severe, you need to pick a fungicide for your rhubarbs. Here is my recommendation which is safe for edible garden vegetables. (Our Pick: Garden Safe Brand Fungicide)

Home Remedy


  • One part of Hydrogen peroxide (3%).
  • Two parts of distilled or freshwater.


  • Gradually add the Hydrogen peroxide to water and make a solution.
  • Pour this into a plastic sprayer and apply it to the plant base.

Caution- Use hand gloves while mixing the ingredients.

4. Pest Attack

Slug on rhubarb leaves

Pests have been the eternal enemies of vegetables. Rhubarbs are not different ones.

In rhubarbs, snails and slugs are the main culprits which cause hollow stalks. These can be found in the garden just after rain splashes. Basically, they feed on the crispy stalks of rhubarb. Sometimes these can also be found in leaves.

You can trace them by feeding symptoms. Slugs and snails have a common chewing pattern of cutting the stem or leaf from the margin.

However, some easy practices can help to drive away these pests from your garden. Keep reading to know more.

Control Measure

Traps and baits are excellent and safe options to attract and kill slugs and snails. You can place some fresh fruit cuts like grapefruit or melons to attract them and then kill them.

If you are a bit uncomfortable with killing slugs and snails, I have another effective option for you; the barriers and repellents. You can place some copper strips or diatomaceous earth near your rhubarb plants. These will distract and slow down their movement.

Introducing predators is another effective idea. Chicken, geese, ducks, turkeys, beetles, nematodes, and birds largely feed on slugs and snails. Through proper management is needed, this method is quite convenient and eco-friendly.

At the final stage of control, you can use chemicals. Some particular pesticides work brilliantly against snail and slug populations. (Our Pick: Safer 5118-6 Insect Killing Soap Concentrate)

Home Remedies

#Remedy 1: Beer Bait


  • Some cans of beer.
  • A sink or bowl with a large opening.


  • Pour half of your sink or bowl with beer.
  • Place it near your rhubarb plants. Snails and slugs will be attracted and drowned in the sink.

#Remedy 2: Eggshell and Coffee Ground Bait


  • One part of eggshell powder.
  • One part of coffee grounds.


  • Mix coffee grounds and eggshells together.
  • Sprinkle this around your rhubarb plants.

5. Nutrient Deficiency

Proper nutrition is very important for plants’ overall growth. Normally, in good garden soil, 68% calcium and 12% magnesium are present. If the level decreases, plants can suffer a lot. In the same manner, calcium and magnesium deficiency often causes hollow stems in rhubarb.

Greenish-yellow mottled patterns in leaves and stunting are the most prominent symptoms of such deficiencies. Most of the time rhubarbs overall growth is suppressed and leaky stems are seen which gradually leads to a hollow one.

So, if you are thinking of how to grow thick rhubarb stalks, you must consider this fact. Let’s check what you can do to deal with nutrient deficiency.

Control Measure

First of all, you need to keep checking the nutrient level of your soil. A soil testing kit can help you in this. If calcium or magnesium level drops, necessary steps must be taken.

Applying mulches or homemade compost can add a good amount of these nutrients in your soil. Use leaf litters and household materials to make compost.

Adding calcium-magnesium carbonates and Epsom salts also helps in increasing the nutrient levels in the soil. These are available in the market. You can also make some of your own. I’m going to discuss it later.

Finally, for a quick fix, you need to pick a balanced fertilizer that will help in combating all the nutrient issues. Here is a safe option for you (Our Pick: Espoma Organic Plant-tone)

Home Remedy


  • 12 grams of calcium nitrate
  • 9 grams of Epsom salt
  • 8 liters of water


  • Add calcium nitrate and Epsom salt in water and make a solution out of it.
  • Apply this to your garden soil near your rhubarb base.

6. Excessive Use of Nitrogen

Extra use of any nutrient can lead to toxicity and severe damage to plants. Excess nitrogen can cause tall and thin stalks in rhubarb which tends to be weak. In the long term, plant stems can turn totally hollow from the inside.

The initial symptoms can be leaf burn with prominent yellowing. These signs are observed after 2 to 3 weeks of fertilizing. If measures are not taken on time, the whole plant may look tall but very weak.

Here are some of my suggestions that will help in overcoming this issue. Keep going through.

Control Measure

On the first note, it is recommended to use a balanced fertilizer for your garden. This will eliminate the risk of nitrogen toxicity. Use the one I have mentioned before.

If your soil is already saturated with excessive nitrogen, simply add some sawdust or wood shaving. While decomposing, these will use the extra nitrogen from the soil. This technique works amazingly in lowering the level.

Did you know some plants can take up that extra nitrogen from the soil? Squash, cabbage, broccoli, and corn are great in this. You can plant these near your rhubarbs and these will reduce the nitrogen level in the soil while benefiting you with some good returns.

Last but not the least, add some extra soil or water your plants heavily to leach out the extra dose of nitrogen from the soil. In this case, check proper drainage also.

7. High Temperatures

Rhubarbs are winter veggies that grow between 4℃ to 23℃ in varying seasons with 6 hours of sun exposure. Extreme temperatures can put your plants in stressful conditions. This can lead to severe cell damage that can cause hollow stalks.

On a hot humid day, your plant may show wilting symptoms. It’s a clear sign that your rhubarbs need some relief. Let’s take a look at how to save your rhubarbs in such a condition.


The very first attempt is to move your plants away from the sun. Well, it’s only possible in the case of the pot-planted ones. But when it comes to garden rhubarbs, you need to provide some kind of artificial shade. You can cover your plants with some plastic sheets in the form of a tent for some time.

After that, you can water your plant deeply but gradually. This will help to reduce the temperature shock. But do not Overwater your rhubarbs.

Keeping the soil moist is also a good strategy to combat extreme temperatures. Mulches work great in such a case. You can use manures or wet garden litters as mulch by placing them close to the plant base. This will help in retaining moisture and allow enough water for rhubarbs to uptake.

Finally, choose a shady place to grow rhubarbs so that they can only have partial sunlight. This will reduce extreme sun damage to a good extent.


What causes rhubarb to be hollow?

The most common reasons behind hollow rhubarbs are water deficiency and high temperatures. When there is a lack of water in the plant body, cells tend to shrink and dry up. Thus, hollowness is created inside rhubarb stalks.

Other important factors are crown rot, imbalanced nutrition, and pest attacks. These can gradually turn your fleshy stalks into hollow ones.

Can you eat hollow rhubarb stalks?

Hollow stalks in rhubarbs do not harm your body or bring any changes to its flavor. These just reduce the growth potential and flowering capability. 

So you can eat them. You only need to be careful about the fact when rhubarb is too old to use. If there is mushiness, mould growth, or any kind of bad smell coming out, it’s better to discard them.

How do you get thick rhubarb stalks?

Being a heavy feeder, rhubarbs need a good dose of nutrients. Growing in well-manured soil will provide a good amount of necessary elements to grow thick rhubarbs. If you are still not satisfied, apply some good quality and balanced fertilizer available in the market. 

Some particular varieties are great in yielding thick stalks. These are MacDonald’s Canadian Red rhubarbs and Cherry Red rhubarbs. You can plant these for thicker stems.


Finally, I have come to an end. Let’s sum it up together. All you need to do is maintain proper watering and nutrition for your rhubarbs with the necessary management steps to combat high temperatures. 

Besides these, take action against pest and fungal attacks and maintain rich soil. It’s not that hard, right? So what are you waiting for? Just follow my instructions according to your needs.

Feel free to ask any queries in the comment section. Also, don’t forget to share your experience.

James Rivenburg
James Rivenburg
James Rivenburg

James Rivenburg is the founder of plantandpest.com, a passionate gardener with valuable experience and knowledge gained through trial and error. The website has a large community of followers who trust his tips and techniques and have succeeded with his advice. He is always Committed to helping others create a beautiful and healthy garden.

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