This occurs as a natural attempt to produce seeds – a means of survival when a plant is put under stress and feels that it is in danger. For this reason, many gardeners also call this “going to seed”.
There are two other reasons rhubarb bolts besides stress: maturity (it may be time to divide and reset the clock on the plants) and the variety of your rhubarb plant(s). Old-fashioned varieties, such as Victoria and MacDonald, are reported to be heavy seed stalk producers. Canada Red and Valentine are less likely to bolt.
Here's how to prevent the seed stalks from forming:
- Harvest stalks regularly: Rhubarb plants tend to produce seeds when they are left to mature and go to seed naturally. By regularly harvesting the stalks, you encourage the plant to focus on producing more edible stalks rather than diverting energy into seed production.
- Remove flower stalks: If your rhubarb plant has already started sending up flower stalks, it's important to remove them immediately. Cut the flower stalks as close to the base of the plant as possible.
- Fertilize! Rhubarb plants require adequate nutrition to thrive. Ensure your plant is receiving sufficient nutrients by fertilizing. Use a balanced fertilizer with equal or slightly higher levels of nitrogen (N) and potassium (K) compared to phosphorus (P). This nutrient balance promotes healthy growth and discourages seed production.
- Mulch around the plant: Apply a layer of organic mulch, such as straw or compost, around the base of the rhubarb plant. Mulching helps suppress weed growth, conserves soil moisture, and maintains a more consistent temperature around the plant. This encourages the plant to focus its energy on producing stalks rather than seeds.
- Divide and replant regularly: Rhubarb plants tend to become less productive as they age. To rejuvenate your rhubarb, divide the plant every few years and replant the healthy divisions. This practice helps maintain vigorous growth and reduces the likelihood of the plant going to seed.
- Maintain proper spacing: Give your rhubarb plants enough room to grow and spread. Crowded plants are more likely to produce seed stalks. Aim to space them at least 3 to 4 feet apart to provide adequate airflow and light.