When to Plant Grass Seed in Colorado? – Planting Tips

Written by

William Golder


Dorian Goodwin

when to plant grass seed in colorado

Whether you are renovating or are just getting started with planting turfgrass, the first step towards having a beautiful lawn is knowing when to plant grass seed in Colorado.

If you are planning to have cool-season grass, any time within the growing season, from March 01 through September 30, would be a good time to sow the seeds.

However, they can establish better on the soil when planted in the late summer season, from mid-August to mid-September. On the other hand, seeding grass in Colorado for warm-season varieties should be done from April 01 to July 31.

The Best Time to Plant Grass Seed in Colorado


Colorado has a diverse geography which includes mountains, high plains, deserts, and canyons.

This, in turn, makes Colorado’s climate quite complex. The state’s hardiness zone spans from zones 3a to 7a and knowing which hardiness zone you are in greatly helps when you are planning to grow grass in Colorado.

  • In Northern Colorado

In cities of Boulder, Brighton, and Fort Collins, sowing grass seeds can be done any time from March 01 through September 30.

  • In Front Range Region

In Denver and in Colorado Springs, which are both in zone 5b, planting grass seeds can be started from mid-August to mid-September

  • In Colorado Western Slope

Planting grass seed in Colorado’s Western Slope region, such as in Grand Junction, Durango, and Montrose is ideally done from mid-August to mid-September, before the first fall frost.

Besides, you also can refer to other topics related to planting grass seed such as the best time to plant grass seed in Minnesota, Virginia, or Pennsylvania.

Tips for Grass Planting


1. Choosing between Warm-season Grass vs Cold-season Grass

Warm-season grasses grow from June to September and as their name implies, they are more adapted to warmer climates and are drought resistant. Cool-season varieties are best grown in fall and spring when temperatures are cooler.

In Colorado, both warm-season and cool-season grasses can thrive. However, for those residing in places with high altitude, grass seed should come from the cool-season varieties. It is ideal to plant them in spring when the soil temperatures begin to warm up.

2. Preparing the Soil


Sowing seeds on unprepared soil is one of the top causes for seeding to fail. Prepare your lawn beforehand by killing weeds using a non-selective herbicide and remove any debris. Work the seed into the soil to ensure that there is a good seed-to-soil contact.

3. Caring for Newly Seeded Soil

The care requirements of a newly seeded lawn can be a little different from that of an already established one. Here are some things to be mindful of when caring for a new lawn:

  • Watering new grass seed is critical to establish a strong and healthy lawn. After planting, thoroughly water the soil especially on hot, windy days.
  • Apply starter fertilizer according to label instructions.
  • As much as possible, avoid foot traffic in the area as seedlings are easily injured.
  • You can begin mowing your new lawn when the grass has grown to 5 to 3 inches.

4. Overseeding Your Lawn


If your grasses are thinning out, you can definitely do a complete overhaul of your lawn but for some homeowners, the option to just overseed lawn in Colorado seems more practical.

In this method, grass seeds are planted directly on existing lawn to make it thicker and repair damaged patches.

CSU Extension suggests that the grass seed for overseeding should be similar in appearance to the existing grass species. For example:

  • Ryegrass can be seeded into existing bluegrass.
  • Fine fescue can be seeded into existing bluegrass.
  • Buffalo grass is not recommended to be mixed with bluegrass, ryegass, or tall fescue.

Frequently Asked Questions


When should I plant grass seed in spring in Colorado?

Spring season in Colorado is typically from March until May and if you are planning to plant grass seeds in spring, it is recommended to plant them after the last frost passes.

In Pueblo, Colorado, for example, the last frost is estimated to be on May 4th, so you can plant your grass seeds any time after this date.

Can you plant grass seed in March in Colorado?

Yes, you can plant grass seeds in March in Colorado. You can select seeds from the cool season varieties such as Kentucky bluegrass and perennial ryegrass.

What grass seed is best for Colorado?

The best grass seed for Colorado lawns is Kentucky bluegrass. This species is the most common type of grass that you will find in Colorado lawns due to its high tolerance to cold and the ability to propagate quickly.

According to CSU Extension, grass seed species also common in Colorado include buffalo grass, blue grama, tall fescue, fine fescues, and perennial ryegrass.

How do I start planting grass seed in Colorado?

Here is a quick guide on how to start planting grass seed in Colorado:

  • Check the average temperature and frost dates in your area.
  • Prepare the soil to ensure good seed germination and growth.
  • Choose the grass variety that is most suitable for your local climate.
  • Sow the seeds and water frequently.
  • Limit foot traffic in the seeded area to prevent injury to the seedlings.
  • Mow the grass when they reach 5 to 3 inches in height.

What are other alternatives to planting grass seeds in Colorado?

For those who are not keen on waiting for grass seeds to grow, another option is to lay sod in Colorado lawns. Though it can be quite demanding in terms of physical labor, laying sod is the fastest way to start a new lawn.


Having a healthy lawn takes time and work but the results sure are worth all the effort. While it can be quite intimidating for beginners, all it takes is giving your lawn the proper care and making sure that seeds are planted at the correct time.

Thus, knowing when to plant grass seed in Colorado will surely help you achieve the lush and green lawn you’re aiming for.

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