Planting Guides

When to Plant Carrots in Boise: Complete Guide + Best Varieties for Zone 6a

Boise, Idaho

USDA Zone 6a

Last Frost: May 5

Last updated: October 30, 2025

Learn when to plant carrots in Boise with specific dates for Zone 6a. Compare 5 varieties, get a complete timeline, and discover which carrots grow best in Idaho's climate.

LLily Nakamura

October 30, 2025

Carrot rows growing in Boise Idaho garden with optimal Zone 6a spring growing conditions — — Image © PlantReference.org 2026

Quick Answer

Plant spring carrots March 15-April 15 in Boise for summer harvest. Plant fall carrots July 15-August 15 for winter storage harvest.

TL;DR

Spring carrots: Plant March 15-April 15 in Boise for June-July harvest. Fall crop: Plant July 15-August 15 for October-November harvest. Daucus carota 'Danvers' and Daucus carota 'Chantenay' handle Boise's clay-loam soils best, while Daucus carota 'Nantes' excels in amended raised beds.

Frequently Asked Questions

What's the best time to plant carrots in Boise?

Plant spring carrots March 15-April 15 when soil reaches 45°F consistently. Plant fall carrots July 15-August 15 for the sweetest harvest after frost. Fall plantings generally produce better quality carrots in Boise's climate due to cool autumn nights that concentrate sugars in the roots.

Which carrot varieties work best in Boise's clay soil?

Daucus carota 'Danvers 126' and Daucus carota 'Chantenay Red Core' handle clay soil beautifully. Their wedge shape and broad shoulders push through heavy soil that stops longer varieties. Avoid Imperator types in clay—they need deep, sandy soil to develop properly. Daucus carota 'Nantes Scarlet' works well if you amend the soil with sand and compost.

How do I prevent carrot seeds from failing to germinate in Boise's dry climate?

Use the board method: plant seeds 1/4 inch deep, water thoroughly, then lay a wooden board directly over the seeded row. Check daily starting day 5 and remove immediately when seedlings appear. The board prevents our dry air from killing seeds before they establish. Never let the soil surface dry out during the 14-21 day germination period.

Can I grow carrots year-round in Boise?

Not quite year-round, but close. Plant spring crops March-April for June-July harvest. Plant fall crops July-August for October-November harvest. With heavy mulching, you can harvest stored carrots through winter until the ground freezes solid. Resume planting in March. The summer gap (May-July planting) produces woody, bitter carrots due to heat.

Why are my Boise-grown carrots forking and splitting?

Forking usually results from hitting hardpan or rocky layers in our clay soil. Double dig beds to 12 inches deep and add coarse sand and compost. Splitting occurs when dry soil is suddenly flooded with water—maintain consistent moisture with drip irrigation or soaker hoses rather than infrequent heavy watering.

How do I deal with Boise's alkaline soil for carrot growing?

Test soil pH first. If above 8.0, apply sulfur at 2 pounds per 100 square feet in fall. Add acidic organic matter like pine needle mulch. Most importantly, ensure good drainage—alkaline soil problems worsen in waterlogged conditions. Daucus carota 'Danvers 126' and Daucus carota 'Bolero' tolerate alkaline conditions better than other varieties.

When should I harvest fall carrots in Boise for best flavor?

Wait until after several light frosts (28-30°F) but before hard freezes (25°F or lower). Typically, this means late October through early November in Boise. Cold weather converts starches to sugars, making fall carrots incredibly sweet. You can continue harvesting through winter if you mulch heavily with straw and mark rows clearly.

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Tagged with

#carrot planting #Boise gardening #Zone 6a #when to plant carrots #Idaho vegetables #clay soil carrots #fall carrots #spring planting #root vegetables #succession planting

Written By

Lily Nakamura

Lily is a Master Gardener and high-desert homesteader outside Boise. She and her husband moved to Idaho from the Bay Area and had to completely relearn gardening for a climate with alkaline soil, intense sun, hard freezes, and limited water. Lily now grows a large vegetable garden, maintains a small orchard of cold-hardy fruit trees, and raises cut flowers for the local farmers market. She writes about the specific challenges of intermountain gardening—short seasons, temperature swings, and the importance of soil amendment in high-pH soils. Lily is honest about the learning curve: high-desert gardening is humbling, and she thinks more gardening writers should admit when conditions are genuinely difficult.