When to Plant Kohlrabi in Pennsylvania (2026 Guide)
Kohlrabi is a fascinating brassica vegetable that thrives in Pennsylvania's diverse climate, making it a perfect choice for local gardeners. With a growing season that varies by USDA hardiness zone, understanding when to plant kohlrabi is crucial. For instance, those in Zone 6a can expect their last frost around April 23, while Zone 5b experiences it later on May 4.
This vegetable, often described as a cross between broccoli and cabbage, produces a bulb-like stem just above the soil that is delicious when harvested at the right size. Kohlrabi cultivars come in green and purple varieties, both of which can be harvested when they're about 3 inches in diameter for optimal flavor and texture. This short time to maturity makes it an ideal gap crop, especially in the transitional seasons of spring and fall.
For Pennsylvania gardeners, especially those in cities like Pittsburgh and Philadelphia, knowing the right timing for sowing seeds and transplanting kohlrabi can greatly enhance your gardening success. Depending on your hardiness zone, you can start seeds indoors or sow them directly, ensuring a continuous harvest throughout the growing season. Let's explore the best practices for planting kohlrabi that will help you cultivate a thriving garden.
Planting Schedule by USDA Zone in Pennsylvania
| Zone | Indoor start | Transplant out | Direct sow | Harvest |
|---|---|---|---|---|
| Zone 6a | Start seeds indoors from March 1 – March 15, ~6 weeks before April 23. | Transplant outdoors from April 24 – May 8, after the last frost. | Direct sow seeds from April 24 – May 8, after the last frost. | Harvest from June 8 – June 23, 45-60 days after transplanting. |
| Zone 5b | Start seeds indoors from February 15 – March 1, ~6 weeks before May 4. | Transplant outdoors from May 5 – May 18, after the last frost. | Direct sow seeds from May 5 – May 18, after the last frost. | Harvest from June 22 – July 6, 45-60 days after transplanting. |
| Zone 6b | Start seeds indoors from February 15 – March 1, ~6 weeks before April 6. | Transplant outdoors from April 7 – April 21, after the last frost. | Direct sow seeds from April 7 – April 21, after the last frost. | Harvest from May 22 – June 6, 45-60 days after transplanting. |
Kohlrabi Planting Windows in Pennsylvania
- Indoor start: For gardeners in Pennsylvania, start kohlrabi seeds indoors between February 15 and March 1.
- Transplant outdoors: Transplant seedlings outdoors in Pennsylvania from April 7 to May 18, depending on your specific zone.
- Harvest: You can expect to harvest kohlrabi in Pennsylvania from May 22 to July 6, based on your planting dates.
Common Mistakes Growing Kohlrabi in Pennsylvania
- One common mistake Pennsylvania gardeners make is planting kohlrabi too late in the season, especially in Zone 5b, where the last frost comes on May 4. It's essential to account for this date when planning your planting schedule.
- Overwatering is another frequent issue, particularly in Pennsylvania's humid summers. Many novice gardeners may not realize that excessive moisture can lead to rot and diseases in kohlrabi plants, which thrive in well-drained soil.
- Some gardeners forget that kohlrabi is a cool-season crop and may mistakenly plant it during the heat of summer. Understanding the appropriate planting times, especially in warmer areas of Pennsylvania, is crucial for successful growth.
- Ignoring the benefits of rotating crops is a mistake that can plague Pennsylvania gardeners. Brassicas, including kohlrabi, should be rotated every three years to prevent soil depletion and disease buildup.
- Another mistake is failing to thin seedlings as they grow. Pennsylvania gardeners may plant too densely, which can lead to competition for nutrients and water, ultimately resulting in smaller, less flavorful kohlrabi bulbs.
Frequently Asked Questions
What if I'm in a cold pocket of Pennsylvania?
If you're in a colder area, consider starting your kohlrabi seedlings indoors earlier than recommended. Adjust your transplanting dates based on local conditions, especially if your last frost tends to occur later than what is typical for your zone.
Can I still plant kohlrabi in May?
Yes, you can still plant kohlrabi in May if you are in Zone 5b, but you should aim to transplant by May 18 to allow enough time for growth. Be mindful of local heat and moisture levels, as these may affect plant development.
How do I know when it's time to harvest kohlrabi?
Kohlrabi should typically be harvested when the bulbs reach about 3 inches in diameter, which optimizes texture and flavor. Keep an eye on your plants, particularly during the warmer months, as they can mature quickly.
Is kohlrabi tolerant of frost?
Yes, kohlrabi is quite frost-tolerant and can withstand light frosts, making it a great candidate for early spring and late fall gardening. Just ensure that you provide some protection during unexpected cold snaps.
What kind of soil does kohlrabi prefer?
Kohlrabi thrives in well-drained, fertile soil with a pH between 6.0 and 7.0. Pennsylvania's clay soils can be improved with organic matter to enhance drainage and nutrient availability, promoting healthy growth.
Keep Learning
City guides in Pennsylvania
Other crops in Pennsylvania
Typical fall sowing window for Kohlrabi in Pennsylvania: August 7 – August 28.