Common Winter Sowing Mistakes (and How to Avoid Them)
Winter sowing is one of the best ways to get a jumpstart on your Denver garden. By planting seeds in mini-greenhouses (like milk jugs) during the colder months, you let nature do most of the work, creating hardy, cold-adapted seedlings that thrive in our unique climate. But, like anything in gardening, winter sowing comes with its own set of pitfalls. Let’s dive into some common mistakes and how you can avoid them for a more successful growing season.
1. Thinking You Can’t Winter Sow in Denver
“Winter sowing doesn’t work in Colorado,” you may have heard. Spoiler alert: Yes, it does! You can winter sow nearly anything, including cold-tolerant vegetables like kale, spinach, and even flowers like poppies and larkspur.
Here’s the trick: Select seeds that can handle fluctuating temperatures and periods of freezing and thawing. These hardy seeds will germinate naturally when the weather warms up, no heat mats or grow lights needed!
2. Bringing Your Jugs Inside During Freezing Weather
We get it—it’s nerve-wracking to see your milk jugs sitting outside during a Denver cold snap. But resist the urge to bring them inside!
Even if it feels freezing, the seeds in your jugs are protected by their mini-greenhouse environment. When you move them indoors, you disrupt their natural cycle, and they might sprout too early.
👉 What You Should Do Instead:
Leave your jugs outside. They’re designed to mimic nature, and the freeze-thaw cycles are what trigger seeds to germinate at the right time.
3. Forgetting to Ventilate Your Jugs
Once your seeds start to sprout in late winter or early spring, ventilation is key. Forgetting to cut slits or poke holes in the tops of your containers can lead to overheating during sunny Denver days or damping off due to excess moisture.
👉 Tip:
As soon as you see seedlings emerging, crack open the tops or remove the lids during warm days to prevent them from getting too hot.
4. Using the Wrong Seeds
Not all seeds are ideal for winter sowing. While hardy, frost-tolerant plants like kale, spinach, and cabbage thrive, warm-season crops like tomatoes and peppers aren’t a great fit for this method.
👉 What Works Best for Winter Sowing in Denver:
Cool-Season Veggies: Kale, spinach, radishes, lettuce, and carrots.
Hardy Annual Flowers: Poppies, calendula, and snapdragons.
Perennial Herbs and Flowers: Lavender, thyme, and coneflowers.
Ready to Start Your Garden Early? Even in the Snow? ❄️
With my 5-Step Roadmap to Winter Sowing, you’ll learn everything you need!
5. Skipping the Labeling Step
It’s easy to get excited and skip labeling your jugs, but come spring, you’ll be left wondering what’s sprouting in each one.
👉 Pro Tip:
Use a Sharpie or weatherproof pen to label your jugs with the plant name and sowing date. For extra protection, write on duct tape or a plant label inside the jug.
6. Assuming Winter Sowing is Only for Experts
Winter sowing might seem intimidating, but it’s actually one of the easiest and most beginner-friendly methods of starting seeds. There’s no fancy equipment required, and it’s incredibly forgiving.
👉 Auntie M’s Advice:
Start with just a few jugs and experiment with different seeds. You’ll be amazed at how satisfying it is to see those little sprouts emerge after months of cold!
7. Letting Your Jugs Dry OuT
Denver’s dry winter air can suck moisture out of the soil in your jugs, leaving your seeds high and dry.
👉 Solution: Check your jugs periodically to ensure the soil remains moist but not soggy. If it’s dry, give them a quick sprinkle of water (but don’t overdo it).
Winter sowing is a game-changer for backyard gardeners in Colorado. By avoiding these common mistakes, you’ll set yourself up for a successful season of strong, healthy plants ready to thrive in Denver’s unpredictable climate.
Ready to try winter sowing? Gather your milk jugs, grab some hardy seeds, and let nature do the rest.
Have questions about winter sowing? Drop a comment below or check out more gardening tips on our blog. Let’s grow something amazing together! 🌱
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Meet the Gardener
I’m Elisa Mack - a mom and Denverite who went from being a green-ish thumb to a kitchen garden fanatic simply by dedicating myself to the study of all things Colorado gardening.
Landscapers don’t design. And nurseries don’t make house calls.
We take a more full-service approach, from designing your dream garden to keeping it beautiful year-round.
And as your coach, I’ll help eliminate the guesswork through every season, no matter your level of knowledge.
