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BUL 965

Spring Vegetable Planting Guide for Idaho

Andres (Andy) West

Idaho green thumb how-to's

Introduction

Are you new to the area? Did you just move here from another state? Are you starting a new hobby with an intent to produce some fresh vegetables? If so, one question that will arise is, when is the best time to plant my garden?

The answer depends on where you live and which crops you want to plant. Optimal planting dates for vegetables vary widely across the state. Elevation and latitude have an impact on planting dates. Also, some crops should be planted before the average last frost date. Others are best planted after the danger of frost has passed. If you are wondering what you can plant and when you can start planting in your region, this planting guide is for you.

Although the chart published here provides ranges of planting dates, they should be used only as a general guide because the weather can fluctuate from year to year. Consequently, make plans based on the recommended dates, but watch your local weather forecast and adjust actual planting activities a few days earlier or later depending on spring conditions.

The first step in using this planting guide is to determine your local hardiness zone. To find your zone, go to https://planthardiness.ars.usda.gov/PHZMWeb/ and enter your zip code. Once you know your hardiness zone, you can use the appropriate columns in the planting guide to estimate the best time for you to plant certain crops in your garden.

Another key point for successful vegetable production in Idaho is understanding the length of the growing season for your local area. Knowing your hardiness zone will not tell you how many frost-free days you will have. One trustworthy source to consult to obtain your area’s average first and last frost dates is The Old Farmer’s Almanac website (https://www.almanac.com/gardening/frostdates). Use these dates and frost-free days values to help you to determine which crops you can grow and to refine planting dates.

Another advantage to knowing the number of frost-free days is it improves your ability to choose adapted cultivars. Most crops offer a choice of cultivars that express a wide range of maturity characteristics. For example, you can get short-day tomatoes (50 days) or long-day tomatoes (90 days). When purchasing seeds or starts, select only those cultivars that fit well within your season length. For specific cultivar recommendations, contact your local county Extension office, your local Master Gardener Program, or a local garden center.

Understanding the difference between cool-season and warm-season vegetables will help as you firm up your planting dates. (See chart; vegetables are listed by cool and warm season.) Cool-season vegetables are those that grow best in temperatures of 50°F–75°F. These vegetables can be planted early in the spring and again in the fall. Warm-season vegetables are those that grow best in temperatures of 70°F–85°F. In short-season areas of Idaho, many warm-season crops benefit from being started indoors and then transplanted to the outdoor garden when temperatures warm and our last frost has passed. Some cool-season crops also grow best if transplanted. Given these options, this planting guide also provides dates for starting plants indoors.

Table 1. General guide of planting dates.
Crop Zones 3-4 Zones 5-6 Zone 7
Start Indoors Transplant Outdoors Start Outdoors Start Indoors Transplant Outdoors Start Outdoors Start Indoors Transplant Outdoors Start Outdoors
Cool Season
Beets May 15–Jun 5 Apr 27–May 18 Apr 17–May 8
Broccoli Apr 17–May 1 May 8–29 Mar 30–Apr 13 Apr 13–May 11 Mar 20–Apr 3 Apr 10–May 1
Brussels sprouts Apr 17–May 1 May 1–22 Mar 30–Apr 13 Apr 13–May 4 Mar 20–Apr 3 Apr 3–24
Cabbage Apr 3–17 May 1–15 Mar 16–30 Apr 13–27 Mar 5–20 Apr 3–17
Carrots Apr 24–May 8 Apr 6–20 Mar 27–Apr 10
Cauliflower Apr 17–May 1 May 1–15 Mar 30–Apr 13 Apr 13–27 Mar 20–Apr 3 Apr 3–17
Collards Apr 17–May 1 May 1–22 Mar 30–Apr 13 Apr 13–May 4 Mar 20–Apr 3 Apr 3–24
Kale Apr 17–May 1 May 1–22 Mar 30–Apr 13 Apr 13–May 4 Mar 20–Apr 3 Apr 3–24
Kohlrabi May 1–22 Apr 13–May 4 Apr 3–24
Leeks Mar 20–Apr 3 May 1–22 Mar 1–16 Apr 13–May 4 Feb 19–Mar 5 Apr 3–24
Lettuce Apr 17–May 1 May 15–Jun 12 Mar 30–Apr 13 Apr 27–May 25 Mar 20–Apr 3 Apr 17–May 15
Onions May 1–22 Apr 13–May 4 Apr 3–24
Parsnips May 8–29 Apr 20–May 11 Apr 10–May 1
Peas Apr 17–May 8 Mar 30–Apr 20 Mar 20–Apr 10
Potatoes May 22–Jun 12 May 4–25 Apr 24–May 15
Radishes Apr 3–24 Mar 16–Apr 6 Mar 5–27
Spinach Apr 17–May 8 Mar 30–Apr 20 Mar 20–Apr 10
Swiss chard Apr 17–May 1 May 8–15 Mar 30–Apr 13 Apr 20–27 Mar 20–Apr 3 Apr 10–17
Turnips May 1–22 Apr 13–May 4 Apr 3–24
Warm Season
Beans Jun 5–26 May 18–Jun 8 May 8–29
Cantaloupe May 1–8 Jun 12–Jul 3 Apr 13–20 May 25–Jun 15 Apr 3–10 May 15–Jun 5
Celery Mar 20–Apr 3 Jun 5–19 Mar 1–16 May 18–Jun 1 Feb 19–Mar 5 May 8–22
Corn May 29–Jun 12 May 11–25 May 1–15
Cucumbers May 1–8 Jun 12–Jul 3 Apr 13–20 May 25–Jun 15 Apr 3–10 May 15–Jun 5
Eggplant Mar 20–Apr 3 Jun 12–Jul 3 Mar 1–16 May 25–Jun 15 Feb 19–Mar 5 May 15–Jun 5
Okra Jun 12–26 May 25–Jun 8 May 15–29
Peppers Mar 20–Apr 3 Jun 12–Jul 3 Mar 1–16 May 25–Jun 15 Feb 19–Mar 5 May 15–Jun 5
Pumpkins May 1–15 Jun 12–Jul 3 Apr 13–27 May 25–Jun 15 Apr 3–17 May 15–Jun 5
Squash May 1–15 Jun 12–Jul 3 Apr 13–27 May 25–Jun 15 Apr 3–17 May 15–Jun 5
Sweet Potatoes May 1–8 Jun 12–Jul 3 Apr 13–20 May 25–Jun 15 Apr 3–10 May 15–Jun 5
Tomatoes Apr 3–17 Jun 5–26 Mar 16–30 May 18–Jun 8 Mar 5–20 May 8–29
Watermelon May 1–8 Jun 12–Jul 3 Apr 13–20 May 25–Jun 15 Apr 3–10 May 15–Jun 5
NOTE: This chart is given as a general guide. Idaho has a very diverse climate, with many pockets and microclimates. These dates are general to the zone; actual dates for your given location may vary by one to three weeks (+/-). Contact your local Extension office for the correct dates for your area.

Additional Reading

Stephen L. Love, Stuart Parkinson, and Kathy Noble. 2009. Choosing and Growing Adapted Vegetable Varieties, University of Idaho Extension Bulletin 863, 13 p. https://www.extension.uidaho.edu/publishing/pdf/BUL/BUL0863.pdf.

Susan M. Bell, W. Michael Colt, Hugh W. Homan, and Dale O. Wilson. 2019 (7th ed.). Planning an Idaho Vegetable Garden, University of Idaho Extension Bulletin 775, 42 p. https://www.extension.uidaho.edu/publishing/pdf/BUL/BUL0775.pdf.

About the Author

Andres (Andy) West—Extension Educator, University of Idaho, Twin Falls County


Issued in furtherance of cooperative extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Barbara Petty, Director of University of Idaho Extension, University of Idaho, Moscow, Idaho 83844. The University of Idaho has a policy of nondiscrimination on the basis of race, color, religion, national origin, sex, sexual orientation, gender identity/expression, age, disability or status as a Vietnam-era veteran.

University of Idaho Extension

 

Physical Address:
E. J. Iddings Agricultural Science Laboratory, Room 10
606 S Rayburn St

Mailing Address:
875 Perimeter Drive MS 2332
Moscow, ID 83844-2332

Phone: 208-885-7982

Fax: 208-885-9046

Email: calspubs@uidaho.edu

Location

Barbara Petty

Email: extdir@uidaho.edu