Introduction to Cold-Weather Gardening

As a gardener in Detroit, Zone 6, I see this advice repeated almost daily: “Don’t start your vegetable gardens until Memorial Day.”

The belief that gardening only happens between the months of May and September has become so ingrained in everyone, and it's often perpetuated by local nurseries that only sell transplants and seeds at the beginning of our warm season.

Tomatoes, eggplants, peppers, cucumbers, and squashes are not frost tolerant and are generally what most people think of when we think of vegetable gardens. The advice, therefore, to not start your garden until all chance of frost has passed is accurate… if we are talking about warm season plants. 

Growing cool season plants gives gardeners like us here in the Midwest the opportunity to extend our growing season in the spring and the fall. Cool season gardening occurs when soil is workable and not frozen, but there is still a chance of frost. When looking at your average temperatures for the month, your cool season months will have highs between 35 and 65 degrees Fahrenheit. Here in Michigan, our cool seasons are March through April and October through November. 

As our cool seasons here are often two-month “shoulder seasons”, it works out perfectly that many cool season vegetables have short days to maturity, meaning you can often have several harvests of cool season vegetables in your garden by the time you turn your vegetable bed real estate over to tomatoes in the spring, or in the fall, by the time it becomes too cold to grow without frost protection. 

The Best Cold-Weather Plants for the Garden

Staples that you can often find in my cold-weather garden include large and long plants such as kale, broccoli, leeks, cabbage, cauliflower, and brussels sprouts. These are grown indoors before then being transplanted into my garden. It is worth noting that learning how to grow these plants from seeds was important for the success of my cool season garden. Nurseries in my area simply do not carry these in the spring or fall.

If seed starting indoors is restrictive for you, you can focus instead on growing plants that can be planted by seed directly in the garden. Carrots, peas, onions, lettuces, spinach, radishes, and beets are all quick-growing plants that thrive in your garden when planted in the spot where they'll grow.

Does your garden have a trellis structure that you use in the summer for tomatoes or cucumbers? Peas will happily use that trellis in the cool-weather months! 

The vegetables I've mentioned not only prefer to grow in cooler weather but also taste better when grown this way too! 

It is also worth noting that the fall is when garlic is traditionally planted. You can plant garlic cloves anytime before the ground really freezes up. This garlic will then stay in your beds through the winter, before it resumes growing in the spring. 

A List of My Favorite Cool-Weather Plants

• beets
• broccoli
• brussels sprouts
• cabbage
• carrots
• cauliflower
• garlic
• kale
• leeks
• lettuces
• mustard
• onions
• peas
• radishes
• spinach

Tips to Grow a Cold-Climate Vegetable Garden

To help you take full advantage of your shoulder seasons in the garden, here are my answers to some of the most frequently asked questions regarding cold-climate gardening.

Q: Should I cover my garden in the winter?

It’s complicated! When we're planting in the cool seasons, we are often bending the seasons just slightly. 

Plants like peas and onions can be started as soon as the ground is workable and don’t need to be covered if a frost unexpectedly happens at night. However, I would keep a fleece blanket, tarp, plastic cover, or something similar on hand for any other seedlings during nights of frost if you don’t have tunnels set up.

While these cool season plants will grow, it is good to keep in mind that we might need to give them some help. Using season extension frost covers is an excellent way to continue growing your established fall garden well into the coldest months of winter. Most cool season vegetables are frost tolerant, but they are usually only hardy down to about 20 degrees. In my case, I can keep my garden uncovered and growing until about November. Once the nighttime lows begin to reach 20, I would cover my garden if I wanted to keep it going. 

In the early spring, covering your garden beds can help warm the soil up a bit faster. After nighttime lows have passed 20, it's acceptable to transplant your larger plants into your garden, but low tunnels can still have a place in helping to protect your young plants from the bright sun, wind, and occasional cold night.  

Q: Should I start seeds indoors? 

Some cool weather plants will need to be started indoors in trays, but not all have to be. 

Ideal choices for vegetables to start from seed directly in your garden outdoors include carrots, peas, radishes, spinach, onions, and lettuces. Most of these cool-weather-loving vegetables will germinate when the soil starts heating up to about 45 to 50 degrees, although germination does take longer at this temperature than it would with soil that is closer to 70 degrees.  

In short, once your soil is workable it is time to start planting! 

Larger transplants that take a long time can be started indoors during the earlier winter months. I recommend starting broccoli, kale, cabbages, celery, and leeks indoors and then transplanting them outside a few weeks after you directly sow your seeds.

Fall cool season gardens can be planted similarly to your spring garden. Direct sow at the end of summer quick-growing plants such as carrots and greens. Larger cool weather crops such as kale and broccoli would need to be started indoors during the middle of summer and then transplanted outdoors at the end of the summer. 

Q: Should I grow in raised beds?

Growing in raised beds makes cold-climate vegetable gardening easier. As a gardener, you will have more control over the temperature of your garden as you push your growing seasons to their limits. Raised beds will warm up in the spring faster than the ground does, which gives your spring growing season a head start by a few weeks compared to in-ground garden temperatures. 

Raised beds are also incredibly easy to adapt with season extension accessories. Cold frames and frost clothes can be added to the beds and secured and will then keep your garden going through the dead of winter. 

Q: How do I plant in the summer around my cool season vegetables?

When planning out your garden space throughout the growing year from spring to summer and back to cool season again in the fall, it is important to note which plants will be staying and which plants will be giving up their space. 

Most cool season vegetables are ready to harvest quickly within two months and don’t need to be considered when planning your summer garden. These include salad greens, cilantro, kohlrabi, mustard, and radishes. 

Then there are some cool season vegetables that won’t be ready to harvest until a little after the summer season starts. These include cabbages, beets, broccoli, cool season herbs, and carrots. You will eventually be able to use this space in your garden, just not right after your frost date passes. 

Lastly, there are some plants that will need to continue to occupy space even through the summer. Kale, leeks, celery, brussels sprouts, onions, and potatoes are a few that come to mind. 

Q: How do I grow the most cool-season vegetables in a small garden space?

It is important to pay attention to the days to maturity and how much space each vegetable takes up when planting. 

In a small garden space, it might be more useful to plant smaller plants such as spinach, lettuce, and carrots that you can harvest several times before summer—rather than just a few large plants that would occupy that same space for a longer period of time. 

In small garden spaces, each square foot counts, and you can choose to spend two square feet growing two cabbages that need several months to reach maturity… or you can choose to plant 18 spinach plants that you'll get to harvest from several times.

You decide how you're going to maximize your extended growing seasons in the garden!

Rachael Carter of Floraculture

After completing degrees in Environmental Science and Biology and working for the EPA, Rachael became hooked on raised bed gardening, which she views as a way to perform work that improves the planet without all the doom and gloom of handling environmental emergencies. Being a garden coach brings her so much joy, especially when she's teaching others how to grow their own food naturally and getting to share her sustainability and environmental knowledge along the way.

Follow her business, Floraculture Gardens, on Instagram and Facebook.

If you live in the Midwest, make sure to subscribe to her weekly newsletter for inspiration and grab your free planting calendar here.