When should I plant seeds ? I live in Colorado Springs colorado

Here are links for anticipated last frost dates.

https://davesgarden.com/guides/freeze-frost-dates/index.php?q=80915

https://davesgarden.com/guides/freeze-frost-dates/index.php?q=80915#b

Count back 6-8 weeks to start your seeds indoors, then harden off for a few days, then plant in ground.

https://www.denverpost.com/2010/03/12/timing-is-everything-when-it-comes-to-plant-seeds/

I'm just north of you. I'm not the most persistent gardener, but I have some successful friends. In our short growing season, it really helps to plant seeds indoors now. Even if they grow a little longer indoors. OR.... buy plants at the nursery that are already going strong and put them straight into the garden in May. This is my preference! Some of the nurseries in Colorado grow all their plants on site. These will be your hardiest plants because not only are they used to our cold nights, but also our altitude which profoundly affects some plants.

Outside, when all danger of frost is past, for Wyoming that is mid May, for you probably sometime in mid April, watch the local weather man, they tell you. For starting seeds inside, any time now is fine.

March - April: onion, garlic, lettuce, peas, radishes, beets, carrots.

May: squash, tomatoes, broccoli, peppers, beans, cucumbers.

Here is a great website to help you know when to plant seeds in CS, CO.

https://garden.org/apps/calendar/?q=colorado%20springs%20colorado

Check the zone on your seed packets, that is your guide.

You should start the seeds indoors now so they will be ready to plant as seedlings in 6 to 8 weeks. Seedlings are so much more dependable than planting seeds directly into the ground, especially where you live, where the temps can still vary greatly in the spring.