Seed Starting and Planting Date Calculator for Denver, CO

Find the best dates for planting vegetables and fruit in your garden! Our free planting calendar calculates the best time to start seeds indoors and outdoors, as well as when to plant young plants outside. 

How to Use The Planting Calendar

Simply put, a planting calendar is a guide that tells you when to start planting your garden. Most planting calendars are based on frost dates, which dictate when you should start seeds and when it's safe to plant outdoors. Our planting calendar is customized to your location in order to give you the most accurate information possible.

On the planting calendar below, please note:

  • The "Transplant Seedlings" dates show when it's typically safe to start planting young plants outdoors. This includes plants grown from seed at home and plants bought from a nursery. (Although frost dates are a good way to know approximately when to start gardening, always check a local forecast before planting outdoors!)
  • When no dates appear in the chart, that starting method is not recommended for that particular plant. Some crops do best when started outdoors rather than indoors, while others prefer the opposite.
  • The Frost Dates indicate the best planting dates based on your local average frost dates. Frost dates are the planting guideline used by most gardeners.
  • The Moon Dates indicate the best planting dates based on your local average frost dates and Moon phases. Planting by the Moon is considered a traditional technique, but some gardeners swear by it!
  • Click on the name of a plant to see our corresponding Growing Guide.

To plan your garden more accurately in the future, keep a record of your garden's conditions each year, including frost dates and seed-starting dates!

30% probability of frost free after May 4 (at DENVER WATER DEPT, CO climate station).
Crop Based on Frost Dates   Based on Moon Dates
Start Seeds IndoorsTransplant SeedlingsStart Seeds Outdoors
Beans May 11-Jun 1
May 15-29
Beets Apr 20-May 11
Apr 30-May 11
Broccoli Mar 23-Apr 6
Mar 23-31
Apr 13-May 4
Apr 15-29
Brussels Sprouts Mar 23-Apr 6
Mar 23-31
Apr 6-27
Apr 15-27
Cabbage Mar 8-23
Mar 17-23
Apr 6-20
Apr 15-20
Cantaloupe Apr 6-13
May 18-Jun 8
May 18-29
Carrots Mar 30-Apr 13
Apr 1-13
Cauliflower Mar 23-Apr 6
Mar 23-31
Apr 6-20
Apr 15-20
Celery Feb 22-Mar 8
Feb 22-Mar 1
May 11-25
May 15-25
Collards Mar 23-Apr 6
Mar 23-31
Apr 6-27
Apr 15-27
Corn May 4-18
May 15-18
Cucumbers Apr 6-13
May 18-Jun 8
May 18-29
Eggplants Feb 22-Mar 8
Feb 22-Mar 1
May 18-Jun 8
May 18-29
Kale Mar 23-Apr 6
Mar 23-31
Apr 6-27
Apr 15-27
Kohlrabi Apr 6-27
Apr 15-27
Leeks Feb 22-Mar 8
Feb 22-Mar 1
Apr 6-27
Apr 15-27
Lettuce Mar 23-Apr 6
Mar 23-31
Apr 20-May 18
Apr 20-29, May 15-18
Okra May 18-Jun 1
May 18-29
Onions Apr 6-27
Apr 6-14
Parsnips Apr 13-May 4
Apr 13-14, Apr 30-May 4
Peas Mar 23-Apr 13
Mar 23-31
Peppers Feb 22-Mar 8
Feb 22-Mar 1
May 18-Jun 8
May 18-29
Potatoes Apr 27-May 18
Apr 30-May 14
Pumpkins Apr 6-20
Apr 15-20
May 18-Jun 8
May 18-29
Radishes Mar 8-30
Mar 8-16
Spinach Mar 23-Apr 13
Mar 23-31
Squash Apr 6-20
Apr 15-20
May 18-Jun 8
May 18-29
Sweet Potatoes Apr 6-13
Apr 6-13
May 18-Jun 8
May 30-Jun 8
Swiss Chard Mar 23-Apr 6
Mar 23-31
Apr 13-20
Apr 15-20
Tomatoes Mar 8-23
Mar 17-23
May 11-Jun 1
May 15-29
Turnips Apr 6-27
Apr 6-14
Watermelons Apr 6-13
May 18-Jun 8
May 18-29