Quick to germinate and grow, tomato seeds are best sown indoors about six weeks before the average last frost date. People in the Denver metropolitan area normally use Mothers' Day as a guide for when to plant. However, Denver had its last spring freeze on April 5 in 1977 and on June 8 in 2007. The average over the last ten years is May 5. Using May 13, 2018 Mothers' Day as a planting date, tomato seeds can be started indoors the first week of April.
Here's a great guide on starting tomato seeds indoors from Modern Farmer:
Colorado State University Vegetable Planting Guide.How to Grow Your Own Tomatoes, Part 1: Starting Seeds Indoors https://t.co/uApuVaugUX pic.twitter.com/DRJDAJ8fKR— Modern Farmer (@ModFarm) March 10, 2018
