How to Plant Rhubarb Seeds? From Seed to Stalk
Planting rhubarb seeds requires patience and attention to detail. To successfully cultivate this tangy vegetable, you need to cold stratify your seeds, sow them indoors or directly into the ground in well-draining soil, and provide them with plenty of sunlight and moisture.
Understanding Rhubarb and its Benefits
Rhubarb (Rheum rhabarbarum) is a perennial vegetable known for its tart stalks, which are commonly used in pies, jams, and sauces. While often treated like a fruit due to its culinary applications, it’s botanically a vegetable. It is hardy and can thrive for many years with proper care. Growing rhubarb from seed can be a rewarding, though sometimes lengthier, process than propagating from crowns.
Rhubarb offers several benefits, including:
- Rich in Nutrients: It contains vitamin K, vitamin C, calcium, and potassium.
- Antioxidant Properties: Rhubarb contains antioxidants that may help protect against cell damage.
- Digestive Health: The fiber content in rhubarb can aid in digestion.
- Garden Beauty: The large, ornamental leaves add visual appeal to the garden.
The Process: From Seed to Seedling
Growing rhubarb from seed requires a slightly more involved approach compared to buying established crowns, but it allows for greater variety selection and is often more cost-effective. Here’s a step-by-step guide:
- Seed Selection and Cold Stratification: Rhubarb seeds need cold stratification to break dormancy. Place seeds in a damp paper towel inside a sealed plastic bag and refrigerate for at least 4-6 weeks.
- Starting Seeds Indoors (Recommended):
- Fill seed trays or small pots with a seed-starting mix.
- Sow seeds about ½ inch deep.
- Keep the soil consistently moist but not waterlogged.
- Provide adequate light, either natural sunlight or grow lights.
- Once seedlings have developed a few true leaves, transplant them into larger pots.
- Direct Sowing (Alternative):
- Prepare a well-draining, nutrient-rich garden bed.
- Sow seeds ½ inch deep and 3 inches apart.
- Keep the soil consistently moist.
- Thin seedlings to 18-24 inches apart once they emerge.
- Transplanting Seedlings:
- After the last frost, harden off the seedlings by gradually exposing them to outdoor conditions.
- Choose a sunny location with well-draining soil. Rhubarb thrives in slightly acidic soil (pH 6.0-6.8).
- Dig holes large enough to accommodate the root balls, spacing plants 3-4 feet apart.
- Plant seedlings at the same depth they were growing in their pots.
- Water thoroughly after planting.
- Ongoing Care:
- Water regularly, especially during dry periods.
- Fertilize in the spring with a balanced fertilizer.
- Remove flower stalks as they appear in the first two years to encourage leaf growth.
- Mulch around the plants to retain moisture and suppress weeds.
Soil and Location Considerations
Rhubarb needs specific environmental conditions to thrive. Here’s what to consider:
- Sunlight: Rhubarb needs at least 6 hours of sunlight per day.
- Soil: Well-draining soil rich in organic matter is crucial. Amend heavy clay soil with compost and other organic materials to improve drainage.
- pH: Aim for a soil pH between 6.0 and 6.8. Perform a soil test to determine your soil’s pH and amend accordingly.
- Space: Rhubarb plants can grow quite large, so provide ample space between plants (3-4 feet).
Common Mistakes to Avoid
Even with careful planning, certain mistakes can hinder rhubarb growth.
- Neglecting Cold Stratification: Failure to cold stratify rhubarb seeds will significantly reduce germination rates.
- Overwatering: Soggy soil can lead to root rot. Ensure the soil drains well.
- Harvesting Too Early: Avoid harvesting stalks during the first year to allow the plants to establish themselves. Only light harvesting is recommended in the second year.
- Harvesting Too Late: Stop harvesting stalks by early summer to allow the plants to store energy for the following season.
- Ignoring Flower Stalks: Removing flower stalks prevents the plant from diverting energy into seed production, promoting leaf growth.
- Planting in Poor Soil: Inadequate soil preparation and lack of organic matter can stunt growth.
Comparing Seed Starting Methods
The table below highlights the differences between starting rhubarb seeds indoors and direct sowing.
| Feature | Starting Seeds Indoors | Direct Sowing |
|---|---|---|
| Timing | Start 8-10 weeks before the last frost | Sow after the last frost when the soil has warmed |
| Control | Greater control over temperature and moisture | Less control over environmental factors |
| Germination Rate | Typically higher germination rate | Can be lower germination rate due to fluctuating weather and soil conditions |
| Plant Size at Transplant | Seedlings are larger and more established when transplanted | Seedlings are smaller and potentially more vulnerable when they emerge |
| Space Requirements | Requires indoor space and equipment (grow lights, seed trays) | Requires garden space prepared for direct sowing |
| Weed Control | Easier to manage weeds in seed trays | Requires more vigilant weed control in the garden bed |
Frequently Asked Questions About Planting Rhubarb Seeds
1. How long does it take for rhubarb seeds to germinate?
Rhubarb seeds typically germinate within 7-14 days under optimal conditions. Maintaining consistent moisture and warmth is crucial for successful germination. Remember, cold stratification significantly improves germination rates.
2. Can I plant rhubarb seeds directly into the garden?
Yes, you can. But starting rhubarb seeds indoors allows you to get a head start and provides better control over environmental conditions. Direct sowing is possible but requires patience and careful monitoring of soil moisture and temperature.
3. What is the best soil for rhubarb?
Rhubarb thrives in well-draining, fertile soil that is rich in organic matter. Amend heavy clay or sandy soil with compost, aged manure, or other organic materials to improve drainage and nutrient content. A slightly acidic soil pH (6.0-6.8) is ideal.
4. How much sunlight does rhubarb need?
Rhubarb needs at least 6 hours of sunlight each day to thrive. Choose a sunny location in your garden where the plants will receive ample sunlight. In hotter climates, some afternoon shade can be beneficial.
5. When is the best time to plant rhubarb seeds?
The best time to start rhubarb seeds indoors is 8-10 weeks before the last frost. Direct sowing should be done after the last frost when the soil has warmed. Transplanting seedlings should also occur after the last frost.
6. How often should I water rhubarb?
Water rhubarb regularly, especially during dry periods. Aim to keep the soil consistently moist but not waterlogged. Mulching around the plants can help retain moisture.
7. How do I fertilize rhubarb?
Fertilize rhubarb in the spring with a balanced fertilizer or compost. Avoid over-fertilizing, as this can lead to excessive leaf growth at the expense of stalk production.
8. When can I start harvesting rhubarb stalks?
Avoid harvesting any stalks during the first year after planting to allow the plants to establish themselves. Light harvesting is recommended in the second year, and full harvests can begin in the third year.
9. Why is my rhubarb plant flowering?
Rhubarb plants produce flower stalks to reproduce. While the flowers are attractive, they divert energy away from leaf production. Remove flower stalks as soon as they appear to encourage stalk growth.
10. What are common rhubarb pests and diseases?
Rhubarb is relatively pest-resistant. However, it can be susceptible to crown rot if the soil is poorly drained. Prevent crown rot by planting in well-draining soil and avoiding overwatering. Slugs and snails can also be a problem; use appropriate control methods if necessary.
11. How long will my rhubarb plant live?
With proper care, rhubarb plants can live for 10 years or more. Regular fertilization, adequate watering, and removal of flower stalks will help ensure a long and productive lifespan.
12. What part of the rhubarb plant is edible?
Only the stalks of the rhubarb plant are edible. The leaves contain high levels of oxalic acid and are toxic to humans and animals. Never consume rhubarb leaves.