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. 

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.

When to…

…start seeds indoors? Mid to late March. 

…directly sow (the act of planting seeds in the garden) cold-tolerant plants like lettuce, greens, and cole crops (a.k.a. brassicas)? Mid-April.

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

Seeds

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 than 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.
  • 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, 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.

Seedlings

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 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. 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 five 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, Erie, Golden, Castle Rock, and Littleton

Echter’s Nursery & Garden Center
A family business since 1959, Echter’s is a massive retail plant and nursery center in Arvada, with 80 percent of annual plants grown on-site and 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.

Read More About Gardening in Colorado

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