When to Plant Tomatoes Outside Colorado

Tomatoes are one of the most popular vegetables grown in Colorado. However, the state's high elevation and sometimes unpredictable weather can make it challenging to know when to plant tomatoes outside. Here's what you need to know.

Understanding Colorado's Climate

Colorado's climate can be quite variable due to the state's unique geography. In general, Colorado has a high-desert climate with low humidity, intense sunshine, and sometimes drastic temperature fluctuations. These conditions can make it challenging to grow plants, including tomatoes, but with a little planning, you can still have a successful harvest.

When to Start Seeds Indoors

If you plan on growing tomatoes from seed, it is recommended to start them indoors about six to eight weeks before the last spring frost date. In Colorado, the average last frost date is typically in mid to late May, but this can vary depending on your location within the state.

Starting seeds indoors will provide your tomato plants with a head start, ensuring they are big and strong enough to thrive once planted outside. Additionally, it will extend the growing season and allow you to harvest your tomatoes earlier in the summer.

When to Transplant Seedlings Outdoors

Transplanting your tomato seedlings outdoors should be done when the soil has warmed up and there is no longer a risk of frost. In Colorado, this is typically in late May to early June, depending on where you live.

Before transplanting, it is important to harden off your tomato seedlings. This means gradually exposing them to outdoor conditions, such as wind and direct sunlight, over a period of several days. This will help prevent shock and ensure your plants can acclimate to their new surroundings.

Choosing the Right Tomato Varieties

When selecting the tomatoes you want to grow, it is important to consider the number of days to maturity. In Colorado, it is recommended to choose tomato varieties that are classified as early maturing or determinate. This will ensure that your plants have enough time to produce fruit before the first frost of the fall.

Some popular early maturing tomato varieties for Colorado include Early Girl, Champion, and Fourth of July. Additionally, cherry and grape tomato varieties tend to have a shorter growing season, making them great choices for Colorado's climate.

Tips for Growing Tomatoes in Colorado

To ensure the success of your tomato plants in Colorado, there are several tips you should keep in mind:

Choose a location with full sun exposure and well-drained soil.

Provide your tomato plants with consistent moisture, but be careful not to overwater.

Consider using a mulch layer to help retain soil moisture and regulate soil temperature.

Monitor for pests, such as aphids and tomato hornworms, and treat as necessary.

Harvest tomatoes as they ripen to promote continued production throughout the growing season.

Conclusion

Knowing when to plant tomatoes outside in Colorado can be tricky, but with the right preparation and knowledge, you can have a successful harvest. Start your seeds indoors early, transplant your seedlings outdoors once the risk of frost has passed, and choose early maturing tomato varieties to ensure a plentiful crop. Following these tips will help you grow healthy and delicious tomatoes in Colorado's unique climate.