When to Plant in Idaho Falls, ID

In Idaho Falls, the gardening season is defined by a median last spring frost date of June 12 and a median first fall frost date of September 5, resulting in approximately 113 frost-free days. These dates set the rhythm for planting and harvesting for local gardeners, creating specific windows for planting cold-tolerant and warm-season crops. Understanding these frost dates is crucial for successful gardening, as planting too early or too late can mean the difference between a bountiful harvest and empty plots.

The intermountain continental climate of Idaho Falls presents a unique gardening environment characterized by a short season and dry conditions, which affect how certain plants thrive. Crops such as peas, radishes, and lettuce do exceptionally well due to the cooler temperatures at the beginning of the season. Conversely, heat-loving crops like sweet potatoes and melons often struggle in this climate because they require longer periods of warmth and a consistent growing season to mature properly. Additionally, the relative dryness of the region can pose challenges that necessitate careful watering strategies for success.

What to plant now in Idaho Falls

Spring: As frost leaves the soil, start planting early crops like peas and spinach around the beginning of April. Transplant seedlings of lettuce by mid-May, ensuring you complete all sowing before the last frost on June 12.
Summer: Once the danger of frost has passed, plant warm-season crops such as tomatoes and peppers after June 12. These should be in the ground by mid-June for best growth, taking advantage of the full summer heat.
Fall: As September approaches, focus on harvesting remaining summer crops. Begin planting fall crops like kale and winter radishes in early September, before the first frost, which arrives on September 5.
Winter: In winter, use this time for soil preparation and planning for the next season. Consider starting seedlings indoors by February to give them a head start ahead of the last frost in May.

In Idaho Falls (85 frost-free days, a short season), 28 of 56 planner crops fit outright, 12 get two plantings, 3 need an indoor start, 1 need a faster variety, 11 don't reliably mature, 1 crop is perennial.

Month by month in Idaho Falls

Month	What to do
January	January in Idaho Falls is cold and snowy, which means gardening is mostly on hold. It's a good month for strategizing your spring garden, organizing seeds, and ordering new varieties.
February	As temperatures slowly rise, consider starting indoor seedlings for cool-season crops. Use this time to research plant varieties that thrive in your intermountain continental climate.
March	March marks the beginning of gardening preparation outdoors. As winter retreats, prepare garden beds, start sowing peas outdoors, and continue caring for your indoor seedlings.
April	April is the ideal month for planting early crops. By mid-April, you can sow lettuce and spinach directly into the ground, taking advantage of the cool soil.
May	May is crucial as the last frost date is June 12. Plan to transplant any seedlings by mid-May to ensure a strong start, and continue sowing quick-growing crops.
June	June brings warmer weather, making it safe to plant heat-loving crops outdoors after the last frost. Aim to transplant tomatoes and peppers by the early weeks of June.
July	July requires diligent watering and care for your summer crops, as temperatures are at their peak. Maintain soil moisture and support growing plants with needed nutrients.
August	As summer wanes in August, begin planning for your fall garden. Start harvesting summer crops early in the month and prepare to sow seeds for fall crops.
September	September is a transitional month with the first frost date on September 5. Focus on harvesting remaining summer crops while planting kale and other hardy greens.
October	October often sees the first frost, which brings an end to most outdoor gardening. Prepare garden beds for winter dormancy, and consider mulching to protect soil during the cold months.
November	November invites frosty conditions; gardening tasks are minimal. Use this time to reflect on the past season and plan for the upcoming year, including selecting new plant varieties.
December	In December, Idaho Falls is typically covered in snow and gardening is dormant. However, it’s a fitting month for organizing your gardening tools and seeds for the next spring.

Frost dates for Idaho Falls ZIP codes

ZIP	Last spring frost (50%)	First fall frost (50%)	Zone
83401	June 12	September 5	5b

FAQ

When is the last frost in Idaho Falls?

The last frost in Idaho Falls typically occurs around June 12, which is an essential date for planning your spring planting.

What vegetables grow best in Idaho Falls?

In Idaho Falls, cool-season vegetables like peas, radishes, and lettuce thrive due to the intermountain continental climate, while heat-loving crops may struggle.

When should I plant tomatoes in Idaho Falls?

Tomatoes should be planted outdoors after the last frost date of June 12, ideally in mid-June for optimal growth.

Can I garden year-round in Idaho Falls?

Gardening year-round in Idaho Falls is challenging due to the cold winters, but planning six months in advance can help you maximize your growing season.

How does Plan My Garden help Idaho Falls gardeners?

Plan My Garden offers tailored planting calendars and expert advice that aligns with Idaho Falls' unique frost dates and microclimate, ensuring successful gardening.