How to Grow Brussels Sprouts in Raised Beds

Brussels sprouts have been the punchline of every kids-hating-vegetables joke for millennia. Today, many are discovering the unfortunate mistreatment Brassica oleracea var. gemmifera received in years past. Delicious when roasted or grated into slaw, this delectable vegetable is undergoing a culinary renaissance and is a must-have for your raised veggie beds this summer (or other seasons, depending on where you live).

The rotten egg smell that earned them their bad reputation is caused by glucosinolate, a sulfur-containing compound, and an enzyme called myrosinase. When overcooked or boiled, myrosinase and glucosinolate break down and release these unpleasant flavors and smells. The good news is that by roasting them in an oven, grill, or skillet, their best qualities emerge. Their outer leaves char and become crispy, while the inside becomes tender with a slightly sweet, nutty flavor. 

They’re a member of the cruciferous or brassica family, along with cabbage, broccoli, cauliflower, kale, and arugula. The sprouts are tiny buds with clumped-together leaves that are rich in fiber, antioxidants, and vitamins K and C. 

In this guide, we’ll show you how to grow these fabulous plants in your raised beds. With a few considerations, this cruciferous vegetable makes a great addition to the raised veggie garden. 

Step 1: Choose Your Seeds

Seedling starts can be difficult to source at nurseries, so I recommend starting your own. There are lots of varieties to choose from, from classics to early bloomers to colorful sprouts. There’s a variety for every garden and kitchen – keep an eye out for these seeds or starts: 

Step 2: Start Your Seeds

When to start seeds is heavily dependent on climate. Brussels sprouts are a slow-growing cool-season veggie harvested in the fall. On average, they take between 80 and 100 days to mature from seedling (about three months). Their flavor benefits from cooler fall weather after they’ve experienced a few frosts, and they can stay in the ground until lows hit 20°F (-7°C). 

The best way to figure out when exactly to start seeds is to count four months back from your first frost date of fall. For example, if your first frost is predicted for October 19, you’ll start your seeds at the beginning of June. Because they’re very sensitive to heat, I recommend starting them indoors under a grow light without a heating pad. They should germinate in two weeks or so. 

If you decide to direct-seed in your raised beds, follow the same rule of thumb by counting backward and adding 20 days. In the example above, you’d want to direct sow in mid-May instead. 

Step 3: Pick Your Site

The first thing to look for is a planting site in full sun (six or more hours of direct sun daily). The second piece is bed size, depending on how many plants you’re growing. They need about 18 inches between plants and two to three feet between rows. If you’re only growing one or two plants, a small bed should do, but more plants will need more space. 

If your brussels will be sharing a bed with other plants, make sure that they’re a good fit for each other. Tomatoes, pole beans, peppers, radishes, and strawberries are poor companions. Good companions are those that repel pests: 

• Aromatic herbs such as dill, chamomile, sage, and rosemary
• Flowers like pyrethrum daisy, geraniums, nasturtiums, and marigolds 
• Alliums like garlic, onions, and shallots 

Step 4: Prepare Your Beds 

With your location picked out, it’s time to get your beds ready. One of my favorite things about raised beds is the precise control over soil and nutrients. Brussels sprouts need well-amended loamy soil rich in nutrients with good drainage and a pH between 6.2 to 6.8 to thrive.  

When amending your soil, add horse or cow manure or well-finished plant-based compost and a dose of nitrogen-heavy fertilizer like blood, bone, or feather meal. If you’re struggling with drainage, mix in perlite or greensand, which has the added benefit of providing iron, potassium, and magnesium. 

As a final step, topdress the soil with mulch. This will help keep the soil cool, retain moisture, and aid in drainage as it breaks down. Keeping the soil as cool as possible for brussels is especially important since raised beds heat up faster than in-ground plantings. 

Step 5: Transplant Seedlings

If you’re starting seeds indoors, transplant your seedlings when they’ve developed five to seven strong leaves. This typically takes about a month and a half. In the week prior to transplanting, harden off your seedlings to help them adjust to full sun and environmental conditions. 

Plant seedlings or sow seeds 18 inches apart in rows two feet apart. If transplanting, be sure to keep them at the same soil level they grew in. Water your seedlings after they’re in the ground. 

Step 6: Provide Care as They Grow  

With your brussels sprouts planted, they need to have some TLC over the next three to four months during their active growing season. While not the most difficult vegetable to grow, they’re not as easy to grow as green beans or zucchini, either. 

Brussels sprouts are heavy feeders and need to be fertilized at least twice during their growing season, but ideally once a month. While a dose of nitrogen-heavy fertilizer is helpful for these plants when they’re initially planted, aim for a 10-20-10 or 13-13-13 fertilizer during their active growing season. For a lower fertilizer NPK, use a 5-5-5 or a 5-7-5 and apply twice a month. Proper feeding and watering are essential to growing delicious sprouts. 

While they benefit from frost, if temperatures drop below 20°F (-7°C), use a frost cloth to protect them. 

Step 7: Watch for Pests 

Brussels sprouts are susceptible to the same pests that plague other brassica plants. These pests include aphids, cabbage worms, cutworms, and cabbage loopers. The good news is that there are many ways to control these pests: 

• Cabbage worms and cabbage loopers: If you see cabbage moths (white wings with a single black dot), chewed-through leaves, or spot these little stinkers on the leaves, your best bet is spraying down the leaves with BT or pyrethrin spray. Keep in mind that these sprays can also negatively affect beneficial insects. Handpicking is tedious, but a great alternative.
• Flea beetles: These small black beetles lay their seeds in the soil and chow down on leaves. Prevent these from destroying your crops by using floating row covers and neem oil, spinosad, or pyrethrin spray to treat them. These are harder to handpick due to their tendency to jump or move to the undersides of leaves quickly.
• Aphids: The bane of every gardener’s existence. If you spot crinkly leaves and aphids underneath them, spray your plants regularly with the flat setting on your hose to remove them. Use an insecticidal soap, neem oil, or horticultural oil to spray them every seven to ten days until they subside.  

As always – the best way to solve these challenges is to do everything possible to prevent them in the first place. Great ways to control or prevent these pests or diseases include: 

• Rotating your brassicas to a new bed every year will help reduce pest numbers and improve soil health. If you have limited space, replace the soil in your beds every three years instead. 
• When watering, use a drip system or aim your hose directly at the soil. Wet leaves can lead to fungal disease, so avoid getting their leaves wet when possible. 
• Use a physical barrier, like a net, over your raised beds to keep out pests. 
• Regularly weed your beds and remove any debris or diseased plants. 

Step 8: Harvest   

You’ll know when your brussels sprouts are ready to harvest when the buds on the stalk reach about one to one and a half inches in diameter and when they’re firm. The exact size of the buds is highly dependent on the cultivar, so check your seed packet. The best time to harvest your brussels sprouts is after they’ve undergone a frost. 

There are two ways to harvest this vegetable. The first way is to snap each bud off one by one from the bottom of the plant if you don’t want to use the entire plant at once. The second way is to harvest the entire stalk at once by chopping it off of the plant or pulling up the entire plant altogether. Brussels sprouts leaves are an excellent stand-in for cabbage. 

They can last over a week in the fridge or up to a year in the freezer. Be sure to discard any yellow or unhealthy leaves before storing them. Keeping them on the stalk will help them last even longer. They can also be pickled for a tangy treat.  

Step 9: Enjoy    

This is my favorite step in the process. My favorite way to enjoy these bite-size veggies is to roast them in the oven at 450°F (232°C) or on the grill until browned and crispy. They can either be roasted individually or on the stalk for a unique presentation. Their leaves can also be roasted and eaten as chips. 

There are an infinite number of ways to enjoy these veggies, but some of my other favorites include using them in slaws or stir-frying them with balsamic vinegar. They don’t need much more than salt and pepper, but lemon and freshly grated parmesan cheese add a tasty touch.