With March’s temperatures soaring on the Colorado Front Range, it’s definitely starting to feel like spring is here. While it’s still too early to plant outdoors, it is time to start thinking about what to plant in the garden, and when. By making a plan for cold season and warm season crops in your vegetable garden this season, you’ll get the most food from your space.
Spring- Cool Season
February and March are the time to start broccoli, cauliflower, kohlrabi, cabbage, and other cool season crops inside. If you haven’t already, get your indoor starts going now. Why start your own, rather than buying plants from the nursery? You’ll be able to grow heirloom varieties only available from seed companies, get plants that meet certain requirements for food preservation or flavor, and, most importantly, save money. A packet of seeds often only costs a few dollars and gives you multiple plants, whereas starts from the nursery can cost a few dollars each!
Wait until April 15 at the earliest, and no later than May 15 (give or take) to plant your cool weather starts, and direct sow appropriate plants at the same time: leafy greens and root vegetables. Cool weather crops will bolt when it gets too hot, so you want the majority of their growing to be finished by the time the hot days roll around.
Cool season crops can tolerate low temperatures, but not all of them are completely freeze tolerant (although I’ve had kale freeze so hard that I was able to snap it off at the stems to harvest, and it thawed out like nothing had happened). Grow in low tunnels, high tunnels, or at the very least keep plastic on hand to ensure your crops last through those late-spring hard freezes and snow storms. And be sure to take a look at my Tips for Getting Through a Colorado Spring.
Summer- Warm Season
March is not too early to start your warm weather crops indoors, so start planning what you want to grow through the summer now. Tomatoes and peppers, along with most annual herbs can be started now and potted-up (placed in larger pots between now and when they go into the ground) to make sure they are a good size before transplanting them. Give them plenty of light and warmth so they don’t get leggy and can develop a good root system before you transplant them (use grow lights or a greenhouse, but be sure to ventilate it so that those warm days don’t fry your starts).
According to Pikes Peak Urban Gardens, you may be able to plant your squash, cucumber, pumpkin, and melons starts and direct sow your warm weather crops as early May 15. I start my squash plants and cucumbers in compostable pots, as these plants hate to be transplanted. Once the soil warms up, around the first week of June, you can gently plant (pot and all) these vegetables into your garden. Check the soil temperature first to make sure it is warm enough (80 degrees or so), and keep a close eye on the weather after you’ve planted and cover against late frosts and hail. Some of these plants are so cold sensitive that even nights that dip into the 40s could stunt them, so be prepared to cover! And pay attention to the low spots on your property: these areas can collect cold air, making micro-climates that can hurt your warm weather crops on cool nights.
Fall- Cool Season
Why stop growing at the end of summer? You can grow cool weather crops again at the end of the growing season, so start your plants indoors in late July or early August to plant in September. The same crops that do well in the spring do well in the fall. In fact, some root vegetables, such as carrots, parsnips, and beets, taste even better if harvested after they freeze because they convert their starches into sugars. They do this to keep the water in their cells from freezing, just as salt on your sidewalk prevents ice. Pretty cool survival method, right? So go ahead, grow into the fall!
And after you’ve harvested, be sure to put your garden beds, and the rest of the farm, to bed for the winter. Fall through early Spring is the time to clean up the yard, add soil amendments, and prune fruit trees (time of year depends on type of tree), among other things. For more ideas about what to do in the fall after the vegetables are harvested, read about Ten Autumn Activities to Make Your Winter Easier.