When to Plant Scallions in Idaho (2026 Guide)
Scallions, also known as green onions or bunching onions, are a delightful addition to any Idaho garden. These versatile crops can thrive in various conditions, providing fresh greens to complement your meals all season long. With careful planning based on Idaho's unique climate, gardeners can enjoy this fast-growing vegetable with ease.
In Idaho, when planning your scallion planting, it's crucial to recognize the significant frost dates that vary by region. For those in Zone 5b—such as Boise—the median last spring frost date is May 6, while fall frosts occur around October 8. This gives you approximately 155 frost-free days to nurture your scallions.
Gardening enthusiasts in Zone 5a, which includes cities like Idaho Falls, should note that the median last spring frost occurs much later, on May 25. Meanwhile, enthusiasts in the colder Zone 4b—home to Rexburg—will need to be cautious, with the median last spring frost on June 12. Understanding these nuances is vital for successful scallion cultivation.
Planting Schedule by USDA Zone in Idaho
| Zone | Indoor start | Transplant out | Direct sow | Harvest |
|---|---|---|---|---|
| Zone 5b | Start March 1 – March 15, ~6 weeks before May 6 | Transplant outdoors after May 6 | Direct sow from May 15 – September 25 | Harvest from June 15 – October 1 |
| Zone 5a | Start March 15 – March 30, ~6 weeks before May 25 | Transplant outdoors after May 25 | Direct sow from June 1 – September 10 | Harvest from July 1 – September 15 |
| Zone 4b | Start April 1 – April 15, ~6 weeks before June 12 | Transplant outdoors after June 12 | Direct sow from June 15 – August 20 | Harvest from August 1 – September 5 |
Scallions Planting Windows in Idaho
- Indoor start: Start your scallion seeds indoors between March 1 and March 30, depending on your Idaho zone.
- Transplant outdoors: You can transplant your scallions outdoors after the last expected frost, which is May 6 for those in Zone 5b, May 25 for Zone 5a, and June 12 for Zone 4b.
- Harvest: Harvest scallions from June 15 – October 1 in Zone 5b, July 1 – September 15 in Zone 5a, and August 1 – September 5 in Zone 4b.
Common Mistakes Growing Scallions in Idaho
- Many Idaho gardeners underestimate the length of the growing season in their specific zones, leading to mistimed plantings. Proper knowledge of local frost dates is essential for successful scallion growth in Idaho's diverse climates.
- A common mistake is sowing scallions too close together, which can lead to overcrowding and reduced yields. In Idaho, the heat and humidity can amplify this problem, so ensure adequate spacing to promote healthy growth.
- Ignoring late spring frosts is another frequent issue. Gardener in Idaho might assume spring is safe for planting, but late frosts can occur into May and even June in colder regions. Always check local forecasts and be prepared to protect your seedlings.
- Not taking advantage of succession planting is another error made by many Idaho gardeners. Scallions can be sown every 3-4 weeks for a continual harvest, so don’t rely on a single planting to cover your needs throughout the growing season.
- Some enthusiasts believe scallions can thrive under any circumstances. However, Idaho's soil can vary greatly, with some areas presenting challenges like excessive clay or alkalinity, affecting the root systems of scallions and their overall health.
Frequently Asked Questions
What if I'm in a cold pocket of Idaho?
If you're in a colder area, consider starting your scallions indoors and transitioning them outside only after frost danger has passed. Utilize season extenders, like row covers or cold frames, to protect your plants during unexpected cold snaps.
Can I still plant scallions in May?
Yes, planting scallions in May is ideal for many areas within Idaho. Just ensure that the last frost date for your specific zone has passed, as planting too early could hinder growth.
How do I ensure a continuous harvest of scallions?
To achieve a continuous harvest, employ succession planting by sowing seeds every 3–4 weeks. This way, you can enjoy fresh scallions from spring through the fall without overwhelming yourself with a single batch.
Can I grow scallions in containers?
Absolutely! Scallions thrive in containers. Use a pot that is at least 6 inches deep and filled with quality potting mix. Plant densely and harvest as needed while leaving the remaining plants to continue growing for a fresh supply.
How can I protect my scallions from frost?
To protect established scallions from frost, consider covering them with row covers or mulching. If severe frost is expected, harvest some plants beforehand and replant scallion bases to ensure a continued supply even through cold spells.
Keep Learning
City guides in Idaho
Other crops in Idaho
Typical fall sowing window for Scallions in Idaho: July 24 – August 14.