Wyoming growers can start planting cool-season crop seeds this January
In the dead of January’s cold, hard frost, starting seeds is likely the last thing on any grower’s mind.
Although outdoor planting is still months away for those in the Cowboy State, it doesn’t mean the growing season has to be on hold.
In fact, multiple expert gardeners note January is actually an ideal time to start a select group of cold-hardy vegetables, leafy greens and slow-growing herbs indoors, giving them a critical head start before Wyoming’s short growing season arrives.
With the help of a few seed trays, some seed-starting mix, a reliable light source and a heating mat, growers can start their gardens long before the soil thaws.
Patience matters
Wyoming encompasses U.S. Department of Agriculture Hardiness Zones Three through Six, with first frost dates ranging from Sept. 8 to Oct. 31 and last frost dates ranging from April 1 to May 16.
Despite the temptation to start early, patience is key, and growers should make decisions based on their specific hardiness zone.
Experts note January is too early to plant warm-season crops like tomatoes, peppers, cabbage, broccoli and cauliflowers in most of Wyoming, as starting them now often leads to leggy plants that outgrow their indoor space long before it’s safe to transplant outside.
Instead, January planting should focus on cool-season crops such as onions, leeks, lettuce, spinach, Swiss chard, kale, Brussels sprouts and strawberries, as well as herbs like basil, oregano, thyme, chives, parsley, cilantro, dill, rosemary, sage, lavender, lemongrass and eucalyptus.
Onions and leeks
According to multiple sources, onions are extremely slow growers when started from seed, making them a standout option for a January start.
Onion seedlings need eight to 10 weeks of indoor growth before transplanting, and as a general rule of thumb, they should grow for 100 to 150 days underground before harvest.
Whether growing storage onions, sweet onions or red onions, starting from seed gives plants more time to develop strong roots and tops before summer daylight triggers bulb formation.
“Starting seeds in January is the ultimate pro move, as it gives onions time to develop a massive root system and plenty of lush tops before the summer solstice,” writes Teo Spangler in a Jan. 5 Gardening Know How blog post. “The more leaves there are by June, the bigger the bulbs will be.”
Spangler recommends planting seeds in well-draining soil in late January and trimming seedlings back as they grow to encourage root development before transplanting them outdoors once soil is workable in early spring.
“Onion seedlings are prone to damping off – a fungal disease,” Spangler adds. “To prevent this, sprinkle a little cinnamon or vermiculite on the planting surface, which acts as a natural fungicide.”
Similar to onions, leeks are very slow growers, often taking up to two weeks to germinate and 120 to150 days to reach full size.
Spangler encourages gardeners to use a seed-starting mix with excellent drainage and trimming seedling tops to one inch once they reach three inches tall.
“This haircut prevents them from becoming top heavy and encourages the plant to direct its energy into building a thick, strong root system and base,” Spangler explains. “When transplanting them in spring, place them in a six-inch deep trench. As they grow taller, pull the surrounding soil inward. This keeps the lower portion of the stem white and tender.”
Leafy greens
Several leafy greens thrive in Wyoming’s cool spring temperatures and are well suited to starting in January.
Multiple sources note mid-January is an ideal target date for starting lettuce, which allows seedlings to be transplanted to a cold frame, hoop house or greenhouse by mid-March and yield fresh lettuce by early April.
Because lettuce seedlings should remain indoors for six to eight weeks, they will need room to grow.
A Jan. 17, 2024 Old Stoney Acres blog post recommends planting varieties like Buttercrunch, Winter Density, Little Gem and Black Seeded Simpson and opting for three- to four-inch containers so seedlings don’t have to be repotted again after a month.
Extremely frost hardy, spinach is another good option to plant in January and can be planted outdoors as early as March, even without protection.
A late-January indoor sowing gives spinach plants a strong start, but experts note container size is key.
“Keep in mind, spinach is one of those plants that doesn’t transplant well,” the Old Stoney Acres post reads. “It has a deep central taproot that doesn’t like being disturbed. Use a larger three- to four-inch pot so when transplant time comes there is plenty of soil around the root ball.”
Popular varieties like Bloomsdale Long Standing and Monstrueux de Viroflay are well suited to early-season growing.
Kale is perhaps the most cold-hardy crop of all and one of the best vegetables to start indoors in mid-January.
Cool temperatures and light frost improve the flavor, making early spring kale sweeter and more tender than summer-grown plants.
Spangler advises, “The best way to grow indoors is to use cell trays filled with a top-quality well-draining potting mix. Plant seeds a quarter of an inch deep, and give the tray a warm site with direct sunshine. Keep the soil moist, and the seeds will germinate in 12 days or so. As they grow indoors, thin them out by snipping every other seedling at the base. Transplant when outdoor soil temperatures reach 50 to 60 degrees Fahrenheit.”
Swiss chard rounds out the lineup of dependable winter-start greens.
Sources note late-January sowings can be transplanted in March with minimal protection.
They also point out chard is slow to germinate, often taking two to three weeks, but once established it is remarkably productive and just a few plants can supply harvests well into summer.
Slow-growing herbs
Many culinary herbs take longer to germinate and mature, making January an ideal time to start them indoors as well. This includes everything from chives, parsley, thyme, oregano, sage and rosemary to eucalyptus, lavender and lemongrass.
Cold-hardy herbs like chives and parsley handle early spring conditions particularly well, while woody herbs appreciate some extra indoor growing time before being exposed to Wyoming’s unpredictable weather.
Herbs destined for containers can also be started now, allowing growers to move them outdoors on warm days and back inside when temperatures dip.
In a Jan. 23, 2024 From Soil to Soul blog post, Maggie Wysocki shares tips for sowing herb seeds indoors.
For oregano, thyme, rosemary, lavender and lemongrass, she recommends sprinkling seeds on top of a seed-starting mix and gently misting with water, being sure not to overwater to avoid dampening off.
She notes seedlings can be thinned out later on and encourages the use of a heating mat to speed up germination and help with root development.
Sage, parsley, chives and eucalyptus seeds can be sowed below the soil.
Hannah Bugas is the managing editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.
