Planting Cold-Tolerant Spring Veggies in the Upper Midwest: Radishes, Spinach, and Peas, Oh My!

When the days start getting longer and warmer in the midwest, gardeners are itching to start planting but know there are still some cold nights ahead and it’s too early to start moving tomato and pepper starts outside. But there are some cold tolerant vegetables and plants that you can seed or transplant almost as soon as the ground is no longer frozen! It’s never too early to start prepping your garden for early planting.

Here are a few cold tolerant garden plants for the anxious gardener. 

Radishes

When planting radishes in the spring, it is best to use “garden” or “salad” type varieties. French  Breakfast Radishes are a classic salad type radish, and Easter Egg Radishes are another popular variety. Daikon and other storage type radishes are best planted in the late summer. This includes Watermelon and Black Radishes as well, so save those seeds for later in the season. 

Radishes can be seeded outside as soon as the ground can be easily worked with a garden hoe. In Minneapolis, this is typically late March to early April. Plant radish seeds about ¼” deep, 1” apart. Radishes should be planted in loose soil and lightly covered with soil. Keep the soil moist by lightly watering your garden if there is not enough rain to keep the soil consistently moist, but be careful not to over water. Thin radishes to about 2” apart they begin to reach a small edible size. (Click here for more info on thinning radishes.) Alternatively, thin the radishes to 2” apart a week after the seedlings have emerged Since the entire radish plant is edible, and the thinned seedlings make tasty microgreens! Just wash gently with water before adding to salads or using as a garnish. Mulch can be added around the rows of radish seedlings to help retain moisture and keep down weeds.

Radishes can be harvested whenever the roots are of a desired size, usually after 3-5 weeks of growth. Plant a new row of radishes every two weeks for a continuous supply. Radishes will begin to “bolt” or develop flowers when the weather becomes hot and the days get longer, and the taste and texture become unpleasant after this, so stop planting spring radishes in mid-May. 

Spinach

Spinach can be seeded indoors in mid to late March. Sunny porches work well for starting spinach because the seeds will germinate in cool temps. Spinach can also be direct seeded outside as soon as the soil can be worked easily with a garden hoe.Transplant starts beginning in mid-April. Plant 2-4 crops, 1-2 weeks apart from each other for a continuous supply. Stop planting spinach by late May, as the weather will become too warm for spinach to grow. 

Plant the spinach seeds ¼ to  ½” deep, 2” apart. After emergence thin the plants to about 2” to 4” apart. Keep the soil moist by lightly watering your garden if there is not enough rain to keep the soil consistently moist, but be careful not to over water. Mulch can be added around the spinach rows to help retain moisture and keep down weeds.

Spinach can be harvested as individual leaves or whole plants. It is best to harvest spinach when it is cool outside to prevent wilting. Spinach won’t last long in the fridge, pick what you need and use it right away. Spinach will “bolt” or start producing flowers if it gets too hot and as the days get longer. (More details on growing spinach here.) If this happens, pinch off the flowers, but this is a sign to harvest and use up your spinach! Or, you can let it flower and save the seeds for a fall crop. 

Peas

There are several varieties of peas. Peas can be either a tall, vining variety or a short, bush or dwarf variety. There are also “snap” and “snow” varieties that are meant to be eaten in the pod, and “shelling” varieties where the peas are removed from the pod and eaten on their own. Check your seed packet for information on the varieties you have selected. Vining varieties need to be provided with a trellis to grow up. Bush varieties can be planted in a single row near a trellis or planted in a wide row, between 12 and 18 inches wide, where the plants will cling to and support each other. (See here for more info.)

Peas can be direct seeded outside as soon as the soil can be easily worked with a garden hoe. Soaking the seeds for 12 hours in room temperature water can help speed up germination. Peas can also be inoculated with beneficial, nitrogen-fixing bacteria called rhizobium. These bacteria pull nitrogen, a vital plant nutrient, from the air and make it available to plant roots in the soil, but the bacteria need plants like peas and beans to act as a host. These bacteria are really great for your garden! Check at your local garden center or farm supply  store for inoculant. To plant peas, make a small trench, plant seeds 1-2” apart, cover with ½-1” soil, and gently firm the soil over the seeds with your hands.  Keep the soil moist by lightly watering your garden if there is not enough rain to keep the soil consistently moist. When watering peas, try to water around just the base of the plants and keep the vines dry to prevent disease. Mulch can be added around the rows to help retain moisture and keep down weeds.

Harvest the tender pods for snap and snow pea varieties when the peas inside have started to plump. For shelling peas, harvest mature pods with large round peas inside before the pods start to turn brown and dry out. Pea vines are also tasty raw in salads or as a cooked vegetable, sauteed or stir fried. 

Lettuce

Lettuce is not as cold tolerant as the other plants in this post, but can still be direct seeded in late April to early May. There are many varieties and types of lettuce, choose your favorite, or get adventurous! Lettuce seeds are tiny, so many come “pelletized” or coated in clay to make them easier to plant. 

Plant lettuce seeds in loose, fine-textured soil without large clods or clumps of soil. If you need to, use a rake or how to break up soil, and rake any large clumps outside of your lettuce row. Make a very shallow trench with your fingers, sprinkle the lettuce seeds into the trench, and then  lightly cover the seeds with soil, no more than ⅛” deep. Gently water the seeds, being careful not to disturb them, as they can wash away or become buried with too much water pressure. Lettuce can also be seeded indoors in trays in mid to late March, then transplanted outside in early to mid May. This works especially well for romaine type lettuces, but not well for looseleaf varieties. Thin or transplant seedlings of heading type lettuces to 8-12” apart. Looseleaf types do not need to be thinned.  Keep the soil moist by lightly watering your garden if there is not enough rain to keep the soil consistently moist, but be careful not to over water. Mulch can be added around the lettuce rows to help retain moisture and keep down weeds.

Lettuce can be harvested as leaves or whole heads, and some types will grow back several times if the base of the stem is left intact. Lettuce will bolt and turn bitter when the weather is hot and when days get longer, so it is best not to plant lettuce after June 1st. (More on growing lettuce here.) If you see lots of milky white sap coming from the stem when you harvest lettuce, this is a sign that the lettuce has turned bitter. 

Conclusion

There are several tasty and nutritious vegetables that tolerate cold weather and are suitable for early spring planting in Minnesota and the rest of the Upper Midwest. Radishes, spinach, peas, and lettuce can all be planted nearly as soon as the soil can be worked in the spring. With a little bit of garden prep and high-quality seeds, you can begin growing fresh produce even when the weather is too cold for most planting. What challenges and successes have you encountered in your garden when planting in the early spring? Let us know in the comments!

Looking for locally-adapted seeds or garden supplies? Stop by Jack’s Hardware and Farm Supply, our friendly staff would be happy to help you find what you need to get started with early spring planting.

Happy gardening!

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Caleb Stellmach

Caleb Stellmach

Caleb Stellmach has been involved in organic vegetable, fruit, and flower farming for over ten years, and he enjoys educating others about gardening, fruit and vegetable growing, and sustainable and self-sufficient living. He is the dedicated Farm and Garden Specialist at Jack’s Hardware and Farm Supply, and he also runs his own urban farm enterprise, Alley Cat Farm.

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