So you want to tend a garden this summer. The good news: Growing your own food and flowers is one of the most rewarding summer activities you can embark upon. The bad news: Thanks to Colorado’s short growing season and high-desert climate (read: low humidity, intense sunlight, chaotic weather), it isn’t exactly the easiest place to hone your green thumb.

That’s why it’s so imperative to start with a good foundation for your garden—and no, we don’t just mean healthy soil. Selecting the right seeds or seedlings (small plants that can be transplanted into your garden) is the key to harvesting success in the Centennial State. Follow our guide and you’ll be digging up sweet carrots, slicing into juicy homegrown tomatoes, and cutting your own fresh flowers in no time. 

Getting Started

Assess Your Space: Choosing the right plant for the right spot is key to success. Consider the sun or shade levels of a planting spot, as well as factors such as northern versus southern exposure. “Try to understand your own microclimate,” suggests Laura Parker, owner of High Desert Seed & Gardens in Montrose. 

Embrace Containers: Just because you lack a backyard doesn’t mean you can’t garden. “If you have limited space, tomatoes and herbs can be grown well in containers,” says Denver Botanic Gardens horticulturist Julia Pearson

Prep Your Soil: Why waste your money on top-quality plants if you’re just going to plop them into Colorado’s often-poor, clay-heavy soil? Keri Luster, site manager at Plum Creek Garden Market’s Littleton location, emphasizes the importance of buying the right kind of soil for your project. Purchase potting mix for containers and ground soil for ground planting because they have been specifically formulated to maintain the proper moisture levels for your plants. And always amend with plenty of compost.

Have Fun With It: “Gardening is an experiment on a mass scale. It’s important for people to understand that you cannot be perfect at gardening,” Luster says. Try to view disappointing yields or dead plants as learning opportunities for next year. 

Fertilize: Yes, your plants need food, too. Chat up your local garden center associate and they’ll recommend the best products for fertilizing ornamental flowers versus produce you intend to eat.

Time It Out: The common belief that Colorado’s outdoor planting season begins on Mother’s Day is a bit out of step with current weather patterns. “Over the past 10 to 15 years, fall is going later and spring is starting later,” Luster says. “Bad weather can really go into the latter half of May.” To be on the safe side and prevent tender plants from frost, you’d be wise to wait to plant warm-weather-loving plants until later in May. To be on the safe side and prevent tender plants from frost, wait to plant warm-weather-loving plants until later in May.

Have Fun With It: “Gardening is an experiment on a mass scale. It’s important for people to understand that you cannot be perfect at gardening,” Luster says. Try to view disappointing yields or dead plants as learning opportunities for next year.

When to…

…start seeds indoors? Mid to late March. 

…directly seed cold-tolerant crops like lettuce, greens, and brassicas directly outdoors? Mid-April.

…plant warm-weather crops like tomato and pepper starters in soil? Late May, when the danger of frost has passed. 


Seed Tips

Starting your garden from seed is by far the cheapest way to go, plus you’ll have access to a wider selection of unique heirloom varieties that wouldn’t typically be available from your average Home Depot. That said, there are a few things to consider: 

  • For warm-weather plants like tomatoes, it’s ideal to start the seeds indoors so that they can get a head start on the short outdoor growing season. To start seeds inside, you’ll need seed trays or containers, soil, water, and a strong source of light, such as a south-facing window or a small grow light. Check out this in-depth guide to starting seeds indoors.
  • Don’t start your seeds too early. “One of the worst things people can do is start plants indoors too early,” Parker says. Avoid root-bound, stressed plants and start yours in mid- to late March. 
  • Most big-box seed companies source their seeds internationally or from other locations in the country, meaning those seeds aren’t necessarily going to thrive in Colorado. Look for seed providers and varieties that have been selected for the unique arid and high-altitude conditions of the intermountain West
  • Want to collect and save your own seeds for next year? Be sure to opt for open-pollinated seeds, which when planted and fertilized will produce a second generation of seeds with the same attributes as the original. Are you more interested in yield, uniformity, and disease resistance? You may want to stick with hybrid seeds, which often have these desired characteristics but cannot replicate them in future generations (the resulting seeds will actually resemble one of the parents of the hybrid).
  • Celebrate biodiversity! Get out of your comfort zone and grow vegetables and flowers you’ve never tried before. 

Where to Buy Seeds Online

High Desert Seed & Gardens

Founded by Parker in 2015, this high-altitude seed farm grows 90 percent of the seed it sells, ensuring that the varieties available will thrive in Colorado’s climate. A partner of the Open Source Seed Initiative, Parker’s larger mission is to build a network of Colorado seed growers and to ensure open access to seeds for generations to come. A few highlights from High Desert include Italian mountain basil, which can withstand cooler temps than other varieties (last year, my mountain basil plants produced all the way into November), incredibly drought tolerant Sonoran white tepary beans, and Collective Farm Woman cantaloupe, an early maturing Ukrainian heirloom. 

High Ground Gardens
Located in the San Luis Valley, this purveyor specializes in open-pollinated, altitude-hardened seeds cultured for high elevations and tough growing conditions. Find stunningly unique plants such as painted mountain corn, Yugoslavian red butterhead lettuce, and sunspot sunflowers. 

Seeds Trust
In addition to selling high-altitude-adapted seeds, this Denver-based outfit includes educational materials on how to save your own seeds. The Seed Buckets are a great value and include just about every type of seed you’d need for your garden in one convenient package. 

Sandia Seed Company
Chile lovers, look no further. This Utah-based company has just about every type of pepper seed you could dream of, including various heat levels of hatch and Pueblo chiles, plus blistering hot Carolina reapers and rare heirloom varieties.

Native Seeds/SEARCH
This Tucson, Arizona–based nonprofit was established in 1983 to protect and preserve the arid-adapted seeds of the greater American Southwest region. Its seed bank includes nearly 2,000 crop varieties representing the farming heritage of more than 50 Indigenous communities from southern Colorado to central Mexico. Find everything from Zia Puebla chiles (an Anaheim-esque variety from Ignacio, Colorado, well-suited to the higher elevation) to striking Calico Lima beans originally collected in Wild Horse, Colorado.

Wild Mountain Seeds
This seed breeding and food production research farm in the Roaring Fork Valley specializes in resilient seeds for farmers and home gardeners. It operates at Sunfire Ranch, a sixth-generation former potato farm in the Crystal River Valley. Its online store is a great source for gardeners looking to embrace biodiversity, as it includes items such as purple blushed tomatillos, potato (smooth) leafed Pink Berkley Tie Die tomatoes, and Mountain Mama sweet corn.


Seedling Tips

  • Don’t waste your money on carrot, radish, or cilantro seedlings. These types of plants all do best planted directly from seed. Melons and pumpkin plants also don’t love to be transplanted. 
  • Many garden centers sell starters in various pot sizes. Larger plants will give you a head start and grow faster than smaller ones, but make sure you have the space for them.
  • Since pepper plants grow so slowly, Luster recommends buying the largest pepper seedlings you can find to help expedite the process.
  • Harden off your starter plants. Most seedlings have been accustomed to the warmth of a greenhouse, so it’s important to slowly acclimate them to outdoor temps. Bring them in and out to experience a little cold before you plant them. 

Where to Buy Seedlings

Sure, you could buy your starter plants from pretty much any supermarket or hardware store. But you’ll find better selection and healthier plants if you shop at a dedicated nursery instead. “The corporate entities go for price over quality,” Luster says. “Your local garden centers are specialists—they know what is going to do well, when to have it, and the appropriate planting time.” You might pay a little more, but you’re buying expertise and quality, which generally translates to much better results. 

Here are a few of our favorite garden centers in the Denver area:

Plum Creek Garden Market
With six locations across the Front Range, these seasonal pop-up markets are a trusted source for vegetables (more than 40 varieties of tomatoes and peppers!), perennials, and annuals. The knowledgeable staff will happily get into the nitty gritty of your garden situation to help set you up for success. Locations in Denver, Northfield, Erie, Golden, Castle Rock, and Littleton

Echter’s Nursery & Garden Center
A family business since 1959, Echter’s is a one of Colorado’s largest retail plant and nursery centers. It grows 80 percent of its annual plants on-site in Arvada and carries a huge selection of flowers. 5150 Garrison St., Arvada

Harlequin’s Gardens
It’s worth the drive to north Boulder to shop at this sustainable nursery and garden center, which specializes in Colorado-adapted plants (peruse the demonstration gardens, where owners Mikl Brawner and Eve Reshetnik Brawner have been testing unique plants since 1985). This is the place to shop for 100 percent organic, heirloom vegetable starters. 4795 N. 26th St., Boulder

City Floral Garden Center
This spacious Montclair nursery offers an extensive selection of vegetable starts grown at its own Golden greenhouse. If you’re in search of herbs for your garden, City Floral’s selection is unparalleled, with plenty of drought-tolerant and unique varieties. 1440 Kearney St.

Aspen Moon Farm
Located outside of Longmont, this nearly 100-acre biodynamic and certified organic farm sells its hardened-off starters at its on-site farm stand and at the Boulder and Longmont farmers’ markets. Depending on seasonal availability, expect everything from raspberry plants and herbs to greens and edible flowers. Aspen Moon also sells its own seeds, including drought-resistant heirloom grains such Turkey Red Winter Wheat and Red Fife Spring Wheat. For updates on plant availability, subscribe to its email list. 7927 Hygiene Rd., Longmont

Nick’s Garden Center & Farmers Market
Family owned and operated since 1987, this Aurora market is a one-stop-shop for all your gardening needs. You’ll find just about every vegetable and fruit variety here, and the website’s handy plant finder tool makes it easy to plan out your garden in advance. 2001 S. Chambers Rd, Aurora

Finding Nectar Nursery
Want to ensure your flowering plants are bee-, butterfly-, moth-, and bat-friendly? Shop at this west Arvada nursery, which was founded in 2021 with the goal of supporting Colorado pollinators. The nursery reopens for spring on April 15 with a wide selection of flowers and herbs, plus Pollinator Garden kits that make designing a beautiful and sustainable garden easy. 15550 Highway 72, Arvada

Jensen’s Flower and Garden
This second-generation, family-owned Lakewood outfit grows its own vegetable and herb starters at its Golden greenhouses, meaning they are already well adapted to survive volatile Colorado weather. 845 Wadsworth Blvd., Lakewood

Tagawa Gardens
The Tagawa family has been operating gardens at this location since 1978. From cool weather crops in early spring to seed garlic bulbs in the fall, Tagawa curates the best varieties for Colorado’s growing environment. In the summer, peruse 150 tomato varieties, 78 pepper varieties, and more than 100 types of herb plants. 7711 S. Parker Road, Centennial

Denver Botanic Gardens Spring Plant Sale
Mark your calendar and bring your own wagon or wheelbarrow for this annual event taking place on Friday, May 12, and Saturday, May 13, at the Botanic Gardens. While the sales include everything from perennials to local seeds, you can also stock up on fruits like berries and plenty of unique vegetables grown from Colorado nurseries, including heirloom Martha Washington asparagus, Armenian cucumbers, and super verde tomatillos. Look for the full plant catalogue on the Botanic Gardens’ website in early May. Admission is free, but reservations are required to enter and capacity often fills up.

Read More About Gardening in Colorado

Colorado Farmers Answer 6 Common Gardening Questions
Everything You Need to Know About Keeping Houseplants Alive in Colorado 

Callie Sumlin
Callie Sumlin
Callie Sumlin is a writer living in Westminster, and has been covering food and sustainability in the Centennial State for more than five years.