Growth Stages and Temperature Needs During germination, Brussels sprouts demand a steady coolness, ideally around 65°F. As they transition to vegetative growth, they’re flexible within the cool spectrum but keep it below 75°F to avoid a growth stunt.
A quick guide to Brussels sprouts
- Brussels sprouts are a fall crop in Minnesota.
- Sow seeds in June, indoors or directly in the garden.
- Water thoroughly once a week for well-formed, large, sweet sprouts.
- They can stay in the garden as long as temperatures remain above 20°F.
Brussels sprouts (Brassica oleracea var. gemmifera) are tight heads of tender leaves, like mini cabbages, grown on the stalk of a tall, leafy plant. The large leaves are smooth and thick and resemble collard greens; you can prepare them in the same ways.
Where each leaf joins the stem, a small sprout develops, beginning with the lowest leaves and continuing up the stalk. The sprouts can be as large as two inches in diameter, but gardeners often harvest them when they are smaller.
Grown as a fall crop in Minnesota, Brussels sprouts are one of the few crops usually harvested after snow has fallen. Flavor improves with cooler fall weather; they can stay in the garden as long as temperatures remain above 20°F.
Since they must mature in cool weather for good quality, plan to harvest from late September in the north, through late October in the southern part of the state and along the Lake Superior shoreline.
Soil pH and fertility
- Have your soil tested.
- Grow Brussels sprouts in well-drained yet moisture-retentive, fertile soil with pH of 6 to 7.
- Apply phosphorus (P) and potassium (K) according to soil test recommendations. Many Minnesota soils have enough phosphorus.
- Unless your soil test report specifically recommends additional phosphorus, use a low- or no-phosphorus fertilizer.
- The plants need to take up water and nutrients throughout their growth.
- Improve your soil by adding well-rotted manure or compost in spring or fall. Do not use fresh manure as it may contain harmful bacteria, and may increase weed problems.
- Side-dress when the plants are about four inches tall.
- Do not use any fertilizer containing a weed killer (“Weed and Feed”), as it may kill your vegetable plants.
Sow seeds indoors in June.
- Use sterile soilless seedling mix and press the seeds ¼ to ½ inch deep.
- Do not use bottom heat. The seeds will germinate and the plants will grow well in regular summer temperatures.
- Seeds should germinate in about two weeks. Once the seedlings emerge, turn on bright grow lights above them.
- Apply fertilizer to developing seedlings beginning when the first true leaf appears. Use a half-strength starter solution once a week. After two true leaves are present, apply fertilizer twice a week.
- When the plants display four or five true leaves after about three weeks, reduce watering. Place plants outside where they will receive wind protection and a couple hours of sunlight.
- Gradually expose them to more sunlight and wind over the next week, being sure to keep them well-watered.
- Dig small holes with a trowel, or dig a furrow with a shovel. Place the seedlings 18 inches apart, and fill the soil around them so that the plant is at the same level it was in its pot.
- Water the plants in, or use a transplant starter solution high in phosphorus and low in nitrogen and potassium.
Brussels sprout seedlings have the distinct appearance of seedlings in the mustard family. The first two leaves to sprout, called “cotyledons,” are fleshy and shaped like capital “Bs”. True leaves follow these cotyledons.
You will need to take particular care of the seedlings. They are most vulnerable when exposed to extreme heat, wind, drought and insects. Water seedlings as needed.
Direct-seeded plants will need as much as three weeks more to mature than plants started indoors, so gardeners in northern Minnesota should use transplants.
Plant seed shallowly (1/4 to 1/2 inch), dropping three seeds every 18 inches. Once the plants emerge, thin so that there is one seedling every 18 inches. Keep the soil moist during emergence.
A row cover will protect the plants from wind and insects during the first weeks of growth. Use a lightweight material so that temperatures do not get too hot under the cover.
If strong winds loosen a floating row cover, it can do more damage than the plants would suffer without it, so be sure to anchor it firmly with soil and/or pins at the edges. You can also support the row cover with wire hoops
Once You Try Brussels Sprouts This Way There Is No Going Back
FAQ
Can brussel sprouts grow in hot weather?
What temperatures can brussel sprouts tolerate?
How do you protect brussel sprouts from heat?
Can brussel sprouts get too much sun?
What temperature should Brussels sprouts be cooked at?
4) Bake the sprouts at a relatively high temperature. High enough to get crispy, golden edges, but not so high that the olive oil burns on the pan and creates bitter flavors. I recommend roasting Brussels sprouts at 425 degrees Fahrenheit. 5) Do not disturb.
What do Brussels sprouts and spinach have in common?
Both are dark green leafy vegetables, which give them rich in soluble fiber and high magnesium content. They are also rich in other vitamins and minerals, such as iron, calcium and phosphorus and vitamins A, K and the B complex. They help reduce blood pressure, help protect eye health, strengthen immunity and contribute to the well-being of the nervous system.
What temperature do you cook sprouts at?
Using too low of an oven temperature. You want that baby hot, hot, hot. Lower temperatures do a great job of softening and cooking vegetables without caramelizing. Higher temps bring out those sugars and help the sprouts cook more quickly (again, to avoid the activation of too much sulphur). I roast my veggies at 450°F.
How do you cook Brussels sprouts if they are loose?
If any of the leaves come loose, don’t worry — just nestle them in around the Brussels. Roast. Then pop them in the oven and cook until the Brussels sprouts are browned a bit on the top and bottom, and any of those loose leaves are nice and crispy. Season. Remove from the oven, and give them a final taste-test.