Your hardiness zone will play a vital role when choosing which annuals or perennials to plant. Flowers, trees, shrubs and vegetables will thrive when grown in their favorable region. The Rocky Mountain region is a combination of zone 4 and 5 with an average “last frost” from May 1 through May 30 and an average “first frost” from September 1 through September 30. This translates to approximately 160 days for growing annuals depending where you live in these regions. Perennials will need to be hardy enough to go through the winter in order to bloom or leaf again in the spring, fall and summer. Compared to more temperate regions this grow season is relatively short although choosing the best plants for your region will increase the success for all of your planting and sowing. Cheers
