When your blooming rhubarb plant starts to bolt, it diverts energy away from the stalks you love to eat. By understanding the triggers like heat and overcrowding, you can take simple steps to stop the flowering process. With consistent watering, proper mulching, and prompt flower removal, you can keep your rhubarb producing tender stalks all season.
There is nothing quite like the taste of homegrown rhubarb in a spring pie or crisp. But imagine walking into your garden one day and finding a blooming rhubarb plant shooting up a tall, thick flower stalk. It can be a real shock! When your rhubarb starts bolting, it changes the entire dynamic of the plant. The stalks you love to eat can become thin and less flavorful. So, what do you do when your perennial veggie decides it is time to flower? Do not panic. Stopping a blooming rhubarb plant from bolting is entirely possible if you act quickly and give your plant exactly what it needs.
Key Takeaways
- Bolting is a stress response: A blooming rhubarb plant usually bolts due to high temperatures, drought, or overcrowding.
- Act fast: Cutting off flower stalks immediately forces the plant’s energy back into growing edible stalks.
- Water deeply: Keeping the soil consistently moist helps cool the plant and prevents heat-induced bolting.
- Mulch is your best friend: A thick layer of mulch regulates soil temperature and retains crucial moisture.
- Divide old plants: Overcrowded roots compete for nutrients, which triggers blooming and bolting.
- Harvest correctly: Pulling stalks gently instead of cutting promotes better regrowth and reduces plant stress.
- Some varieties bolt less: Choosing modern, slow-bolting rhubarb varieties can save you a lot of trouble.
📑 Table of Contents
What Does It Mean When a Rhubarb Plant Bolts?
The Science Behind the Flower
Bolting is simply a plant’s natural response to stress. When a rhubarb plant feels threatened, its survival instinct kicks in. It decides it might not live much longer, so it rushes to reproduce by producing flowers and seeds. For a blooming rhubarb plant, this means all the energy that usually goes into growing thick, tart stalks suddenly diverts into pushing up a towering flower spike. While the flowers are actually quite pretty and ornamental, they signal the end of the delicious stalk production for the season.
Why Does Your Blooming Rhubarb Plant Bolt?
Understanding the root cause is the first step to stopping it. A blooming rhubarb plant does not bolt without reason. Usually, it is reacting to its environment.
Heat and Temperature Swings
Rhubarb is a cool-season crop. It thrives in temperatures between 40°F and 75°F. When the summer heat suddenly spikes, the plant gets stressed. If your rhubarb is planted in a spot that gets scorching afternoon sun, it will likely bolt to try and set seed before the heat kills it.
Overcrowded Roots
Rhubarb plants are heavy feeders with massive root systems. If a plant has been sitting in the same spot for five or more years without being divided, the roots become incredibly crowded. This competition for water and nutrients stresses the plant, pushing it into survival mode and causing it to bolt.
Plant Maturity
Older rhubarb plants are naturally more prone to bolting than younger ones. As the crown ages, it becomes larger and more complex, and it simply wants to reproduce. If you have an older patch, you need to be extra vigilant about watching for flower stalks in the late spring.
How to Stop Your Blooming Rhubarb Plant from Bolting
Once you spot that dreaded flower spike, you need to take immediate action. Here is exactly how to stop your blooming rhubarb plant in its tracks.
Snip the Flower Stalks Immediately
This is the most important step. The moment you see a thick, round stalk emerging from the center of the plant (which looks very different from the edible leaf stalks), cut it off at the base. Use a sharp pair of pruning shears or a knife. Do not pull it, as this can damage the crown. By removing the flower stalk right away, you force the plant to redirect its energy back into growing those edible stalks.
Water Deeply and Consistently
Water stress is a massive trigger for bolting. Rhubarb has shallow roots that dry out fast. During dry spells, give your plants a deep soaking at least once or twice a week. A deep watering encourages the roots to grow downward, making the plant more resilient. Avoid light, daily sprinklings, which only wet the surface and encourage shallow roots.
Apply a Thick Layer of Mulch
Mulch is a game-changer for rhubarb. A 3 to 4-inch layer of organic mulch, like straw, shredded leaves, or wood chips, will keep the soil cool and lock in moisture. This regulates the soil temperature during sudden heatwaves, taking the stress off your plant and preventing it from bolting. Just keep the mulch a couple of inches away from the actual crown to prevent rot.
Divide Overcrowded Crowns
If your rhubarb patch is several years old and constantly bolts despite your best care, it is time to divide the plant. Do this in early spring or late fall when the plant is dormant. Dig up the entire crown and use a sharp spade to cut it into sections, making sure each section has at least one healthy bud and a good set of roots. Replant the divisions in well-prepared soil. If you need a refresher on preparing the earth, check out these proper planting techniques to give your divided rhubarb the best start.
Best Practices for Rhubarb Care to Prevent Bolting
Prevention is always better than cure. Setting up your rhubarb for success from day one will stop bolting before it even starts.
Choose the Right Variety
Some rhubarb varieties are much more prone to bolting than others. Older, heirloom varieties often bolt frequently. If you are planting a new patch, look for modern cultivars specifically bred to be slow-bolting. Varieties like ‘Canada Red’ or ‘Crimson Red’ are known for being reliable producers that rarely send up flower stalks.
Harvest Stalks Correctly
How you harvest rhubarb matters. Never cut the stalks with a knife. Instead, grasp a stalk near the base, twist it gently, and pull it away from the crown. This cleanly removes the stalk without leaving a stub that can rot and invite disease into the crown. Always leave at least a third of the stalks on the plant so it can photosynthesize and store energy for next year. When you are just starting out, learning how to plant rhubarb in the right location with plenty of space makes future harvests much easier.
Is It Too Late? What to Do After Bolting
Sometimes, despite your best efforts, a blooming rhubarb plant will complete its flowering process. Is all hope lost? Not at all!
Adjust Your Expectations
Once a rhubarb plant has fully bolted, the edible stalks may become slightly tougher and less tart. They are still perfectly safe to eat, just not as prime as they were before the flowering. Use these stalks in pies, jams, or sauces where they will be cooked down with plenty of sugar.
Feed the Plant
Bolting takes a massive toll on a rhubarb plant. It uses up a huge amount of stored energy. After you cut off the flower stalks, give your plant a boost by feeding it a balanced, slow-release fertilizer or a generous top-dressing of compost. This will help it recover and store enough energy to survive the winter and produce well next spring.
Common Mistakes to Avoid
Even with good intentions, gardeners can accidentally make bolting worse. Avoid these common pitfalls.
Over-fertilizing with Nitrogen
While rhubarb is a heavy feeder, giving it too much nitrogen can cause a burst of weak, sappy growth that is highly susceptible to heat stress and bolting. Stick to balanced fertilizers or well-rotted manure instead of high-nitrogen chemical feeds.
Ignoring the First Sign of a Flower
Many gardeners wait to see if the flower stalk will “just go away.” It will not. Every day that flower stalk remains on the plant, it is sapping energy from the edible stalks. Cut it the very day you spot it.
Planting in the Wrong Spot
Rhubarb planted in full, blazing sun is a recipe for bolting. These plants prefer a spot with morning sun and afternoon shade. If your rhubarb is in a hot spot, consider transplanting it in the fall to a cooler location. When moving perennials, remember that planting deep-rooted perennials correctly ensures they establish well without extra stress.
Conclusion
Dealing with a blooming rhubarb plant can feel like a gardening emergency, but it is completely manageable. By understanding that bolting is a stress response, you can take steps to keep your plant cool, hydrated, and well-fed. Remember to cut those flower stalks the moment they appear, keep the soil moist with a thick layer of mulch, and divide your plants every few years to prevent overcrowding. With a little bit of attention and care, you can stop your rhubarb from bolting and enjoy a bountiful harvest of thick, juicy stalks season after season.
Frequently Asked Questions
Can you eat rhubarb after it bolts?
Yes, you can still eat rhubarb stalks after the plant has bolted. However, the stalks may become slightly tougher and less flavorful than usual. It is best to use them in cooked dishes like pies, jams, or sauces rather than eating them raw.
Is rhubarb flower poisonous?
While the stalks are perfectly safe to eat, the leaves and the flowers of the rhubarb plant contain oxalic acid, which is toxic if consumed in large quantities. You should always discard the leaves and the flower stalks, sticking only to the edible leafstalks.
How do I know if my rhubarb is about to bolt?
You can tell your rhubarb is about to bolt when you notice a thick, round stalk emerging from the very center of the plant. This flower stalk looks distinctly different from the flat, edible leaf stalks and will quickly grow tall and produce buds at the top.
Should I let my rhubarb flower?
Generally, you should not let your rhubarb flower if you want the best harvest. Allowing the plant to bloom diverts energy away from the edible stalks, making them thinner and less tasty. However, if you want to collect seeds or enjoy the ornamental flowers, you can let one stalk bloom while removing the others.
What is the best mulch for rhubarb?
The best mulch for rhubarb is organic material that retains moisture and keeps the soil cool. Straw, shredded leaves, grass clippings, or well-rotted compost are all excellent choices. Apply a 3 to 4-inch layer around the base of the plant.
How often should I divide rhubarb to prevent bolting?
You should divide your rhubarb plants every 4 to 5 years to prevent overcrowding and reduce the chances of bolting. The best time to do this is in early spring when new growth is just starting, or in the fall when the plant is going dormant.