Cool Season Vegetables for Spring Planting
Marjory Blare, Master Gardener
There are a number of “cool season” vegetables that can be planted outdoors in early spring. Get a head-start on your planting by starting your seeds indoors and planting them out when the temperature is right. Cool season vegetables can be planted out much earlier than, for example, tomatoes or peppers. You can seed indoors as much as six to eight weeks before the last frost date! Read this article for valuable information about seeding and planting “cool season” vegetables.
Cool Season Vegetable Wisdom
Here are some tips for growing “cool season vegetables:”
The best way to get an early harvest is to prepare your garden in the fall. But if you didn’t, you can make up for it by first cleaning up any debris and then warming the soil with black plastic.
If you want to get out in the garden ASAP, row covers and low tunnels can help to create a warmer growing environment for your plants.
The last frost for Dakota county is around May 2nd.
The northern half of Dakota county is zone 5a and the southern is 4b, make sure your seeds are rated for these zones.
Specific crops vary, but the ideal temperatures for cool-season vegetables are in the 50°- 60° range for the first month of growth. Use a soil thermometer to check soil temperature.
Use the right set-up to start seeds indoors: https://extension.umn.edu/planting-and-growing-guides/lighting-indoor-plants#types-of-grow-lights-2651610 and visit the Dakota County Master Gardeners YouTube channel for videos on seed starting.
Starting spring crops under lights can provide a few weeks of optimal growing temperatures.
The transplants will be able to photosynthesize better because of a greater leaf area.
Your plants will usually mature more before temperatures get too hot.
Older plants are better able to withstand feeding damage from early spring insect pests like flea beetles and cabbage maggots.
Cool season vegetables such as Arugula, Chinese cabbage, Bok choy, Peas, and Parsnips can be direct-seeded as soon as the soil is workable.
Chinese Cabbage, Bok Choy, Spinach and Swiss chard can be started under lights or direct-seeded.
Cauliflower is best planted mid-summer for a fall crop.
Harden-off your seedlings before planting them out: https://extension.umn.edu/planting-and-growing-guides/starting-seeds-indoors#hardening-off-seedlings-1179860
There are many edible, cold-tolerant flowers, and herbs, that can be started under lights. Take a look at the chart below for some great ideas.
Vegetable | Days to Harvest | Start seeds | Transplant | Varieties |
Broccoli | 85-100 | 7-Mar - 21-Mar | 18-April | ‘Green Magic, ‘Super Dome’, ‘Jade Cross’ |
Brussels Sprouts | < 100 | 7-Mar - 21-Mar | 18-April | ‘Gustus’, ‘Hestia’, |
Cabbage | 78 | 22-Feb - 4-April | 4-April - 2-May | ‘Ruby Perfection’, ‘Tendersweet’, ‘Omero’ |
Collards | 60-80 | 8-Feb - 7-Mar | 4- April | ‘Tiger’, ‘Ole Timey Blue’, ‘Cascade Glaze’ |
Green Onions | 8-10 weeks | 25-Jan - 8-Feb | 4-April | ‘Feast’, ‘Deep Purple’, ‘White Spear’ |
Kale | 25-65 | 22-Feb - 7-Mar | 4-April | ‘Rainbow Lacinato’, ‘Dazzling Blue’, ‘Black Magic’ ‘Toscano’ |
Kohlrabi | 45-60 | 22-Feb - 7-Mar | 4-April | ‘Kolibri’, ‘Kossak’, ‘Purple Vienna’ |
Leeks | 80-145 | 8-Feb - 22 Feb | 18-April | ‘Tivi’, ‘Electra’, ‘Titian’ ‘Varna’ |
Lettuce | 30-70 | 29-Feb - 14-Mar | 4-April - 11-April | ‘Esmerelda’, ‘Little Gem’ ‘Red Salad Bowl’, |
*Find more information on dates at: https://www.johnnyseeds.com/growers-library/seed-planting-schedule-calculator.html
For Master Gardener-recommended varieties of many vegetables and flowers, here is the link to 42 years of University of Minnesota Extension seeds trials:
Now is the right time to plan for starting seeds indoors!
Happy gardening!
Photo Credits:
Photo 1 – Marjory Blare, Photo 2 – Natalie Hoidal, University of Minnesota Extension, Photos 3 – 5 – Marjory Blare