How to Grow Cool-Season Vegetables
Growing cool-season vegetables in the fall or spring is a satisfying way to maximize your gardening season and enjoy fresh produce throughout the year. Here’s a handy guide for success this spring.
Are you itching to start gardening again, despite the cold weather? Consider growing cool-season vegetables. These hardy varieties can withstand frosts and freezes, ensuring you have the opportunity to enjoy fresh produce early in the growing season.
Your growing strategy needs to change slightly compared to summer to master cool-season vegetables. Success depends on choosing the right varieties and watching the weather so you can plant at the best opportunity.
Here’s how to get started.
Cool-season vegetables are varieties that will tolerate colder weather. They can be planted early in the spring, long before the soil has warmed enough for tomatoes, peppers, and other garden staples.
Most will mature while the weather is cold, meaning that they tend to be the first produce you can pull from the garden. In fact, hot temperatures often cause these crops to “bolt” by going to seed and becoming too bitter to eat.
Your growing zone will have the most significant impact on what cool-season vegetables will thrive in your garden. Determine which zone you are in by using an online lookup tool, and research the average first and last frost dates for your location.
Most cool-season crops can be planted outdoors once the soil and air temperature stay consistently above 40 degrees F (4 degrees C). In comparison, warm-season vegetables like tomatoes and eggplants need temperatures above 70 degrees F (21 degrees C) to thrive.
Cool-season vegetables are split into two categories: cold-hardy and semi-hardy.
Cold-hardy vegetables handle extreme temperatures the best. Seeds germinate well in cool soil, and young plants can withstand a heavy frost. You can direct-seed or transplant them up to three weeks before the last frost date of spring for a reasonable chance of success.
Examples include broccoli, Brussels sprouts, cabbage, collards, kale, leeks, onions, spinach, and kohlrabi.
Semi-hardy vegetables are slightly more delicate. They can withstand light frosts but don’t do well in sustained temperatures below 40 to 50 degrees F (4-10 degrees C). You can sow them up to two weeks before the average last frost date, but waiting a little longer may lead to bigger harvests.
Examples include beets, carrots, lettuce, Chinese cabbage, cauliflower, parsley, and peas.
It’s also possible to plant many cool-season crops in the fall. Many — such as spinach, lettuce greens, and radishes — require short growing seasons. This means you can plant them in late summer to harvest before winter.
Late-summer gardening also gives you the advantage of harvesting your produce after most insects have died or entered winter dormancy. You may need to deal with them while things are sprouting, but few will be left as winter approaches. The same principle applies to weeds — most will slow down or stop growing by harvest time.
Note that the growth rates of fall crops will be the opposite of those grown in the spring. You’ll start with fast growth that will slow down exponentially as the days get shorter and the temperatures drop.
Make sure you read seed packets carefully before fall planting to ensure there are enough days left in your growing season for the plant to reach maturity. After all, there’s nothing worse than a cold snap killing your snap peas before you can harvest them.
Here are some final tips for growing cool-season crops successfully.
When it comes to early spring planting, outdoor temperatures can be deceiving.
Your region might go through a heat wave that warms the air without making much impact on soil temperatures. Go only by how it feels outside, and you might plant your seeds in soil too cold for them to germinate in.
It’s better to use a soil thermometer (available in most garden shops) to gauge the temperature before putting seeds or seedlings in the ground. In a pinch, you can use any thermometer that goes down to freezing.
Late- or early-season planting is always a risk. You might accidentally put seeds in soil so cold they never sprout, or deal with an unexpected heat wave that makes everything bolt prematurely. You’ll do better mentally if you accept that there are risks with every growing season and understand that you probably won’t harvest everything you plant.
One of the worst fates to befall cool-season crops is unseasonably warm weather. Consider harvesting your greens and other vulnerable crops early if a heat wave is in the forecast, so you don’t lose your harvest to bolting.
The weather tends to be most unpredictable in the spring and fall. Keep supplies on hand to protect cool-season crops from wind, rain, and other conditions. You can also utilize low tunnels covered in greenhouse plastic or floating row cover to keep plants safe from the elements and a few degrees warmer than the outside temperatures.
There’s no way to predict ahead of time how your cool-season crops will do. You can improve your chance of having successful harvests by staggering plantings by a week or more.
This way, if cold weather or a heat wave kills off one generation of vegetables, you’ll have some planted of the same variety that may have been large or small enough to survive.
Growing cool-season vegetables is a lesson in patience, but the results can be well worth the effort. Take time to set up a planting strategy, and you may be enjoying fresh garden produce when everyone else is relying on the grocery store.