How to Grow Broccoli in Raised Beds: A Complete Guide
Broccoli is a delicious and nutritious cool-weather vegetable. It needs plenty of sunlight, cool temperatures, and a bit of space. In this article, gardening expert Liessa Bowen provides some valuable tips on how to grow broccoli in a raised bed.
Contents
Broccoli is a member of the brassica family, along with cauliflower, Brussels sprouts, kale, and cabbage. These cool-season crops thrive in the early spring and fall, with ideal temperatures between 65 and 75 degrees F. In most climates, broccoli will be one of the earliest crops you start in the spring or one of the last crops you harvest before winter.
When you’re working with limited space or non-ideal conditions, raised bed gardening is a great option. Fortunately, you can grow broccoli in raised beds! You can grow a single plant or a small group of plants in a raised bed setup. You’ll need to give your plants some attention during their growing season, but your efforts will be rewarded when you enjoy your very fresh and locally grown veggies.
One of the biggest challenges for growers will be a battle against insect pests. Unfortunately, brassicas are favored by a variety of voracious insects. If you have enough space, I recommend using some companion plants to help deter insects and add some diversity to your veggie patch.
One of the best things you can do for your garden plants is set them up for success. Check the following tips to help your plants succeed in a raised bed setting. Let’s dig right into the details about everything you need to know to grow broccoli in a raised bed.
Choose a Variety
If you’ve only seen one common variety of broccoli at your local grocery store, you might be surprised how many different types there are. You’ll find quite a few varieties to choose from, especially if you plan to start from seed.
You may be looking for something that appears very traditional, like the broccoli you buy from the store, with large, dense, green heads. Perhaps you are looking for smaller, more tender heads. Or maybe you’re in the mood for some extraordinary color for your next dish.
‘Di Cicco’
This classic variety produces several small and medium-sized heads, so you’ll be sure to have plenty of tasty green veggies to enjoy all season! ‘Di Cicco’ is an Italian heirloom variety that’s been around since 1890.
‘Burgundy’
If you prefer your broccoli to be purple rather than green, ‘Burgundy’ may be the ideal plant for your tastes. This tender variety is full of delicious flavor and fantastic color that’s as ornamental as it is tasty!
‘Waltham 29’
‘Waltham 29’ is the quintessential variety, with bright green heads and a hint of blue in the shoots and leaves. This prolific plant produces abundant and delicious heads for your next salad, dip, or roasted veggie platter.
‘Belstar’
‘Belstar’ is a great variety for slightly warmer climates and can be started in the spring for late summer harvest. This is one of the more heat-tolerant varieties that still produces plenty of tasty and tender large heads, followed by more, smaller side shoots.
‘Rapini’
This Italian crop produces an abundance of small, tender heads with deliciously spicy leaves that can be cooked or enjoyed raw in salads. ‘Rapini’ is a versatile vegetable that you’re sure to love having in your kitchen.
Raised Beds
Luckily for gardeners, there’s a wide variety of raised beds to fit almost any gardening space. Broccoli plants grow quite large but have a fairly shallow root system, so your raised beds don’t need to be very deep. The raised bed depth could be anything from six to 18 inches and offer your plants plenty of soil for their roots. The lower, wider models are ideal and versatile enough to be used with all your other garden veggies as well.
Spacing your plants at least two feet apart allows plenty of space for these large leafy plants to absorb plenty of sunlight and water. Since broccoli is a bit of a space hog, you will appreciate using a larger-sized raised bed if you want to grow several together. A three-foot square raised bed would allow you to grow just four plants and nothing more, so the more space you have, the more flexibility you will have.
Prepare the Raised Beds and Soil
High-quality soil is an extremely important foundation for any gardening project. Fortunately, it doesn’t matter what type of soil occurs naturally in your yard, because when gardening in raised beds, you have the ultimate control over your soil quality.
Broccoli loves organically rich, well-drained soil. You can use a pre-prepared soil blend designed for raised beds; these soil blends usually have fertilizers or compost added, as well as porous materials to help improve drainage. You can also mix your own raised bed soil by using a blend of topsoil or garden soil, some form of nutrient-rich organic compost, and materials such as pearlite or vermiculite to help improve drainage.
Go ahead and have your raised beds set up and filled with soil by the time your plants are ready to go in the ground. If you’re starting your seeds in the spring, the raised beds and soil should be ready for planting by early spring. If you’re hoping for a fall crop, your raised beds should be ready by mid to late summer. When you plant broccoli after a different spring or summer crop, make sure to clear that previous crop out first so there won’t be any competition between your plants.
Start Your Plants
It’s fun and rewarding to start broccoli from seed, and you will have more choices than if you buy young plants from a garden center. For a spring harvest, direct sow the seeds four to six weeks before the average last frost date in your area. For a fall harvest, direct sow the seeds in late summer or early fall. Keep the seeds moist until they sprout.
You can get a jump start on the growing season by starting your seeds inside. Start seeds indoors up to 12 weeks before your average last frost date. This gives the plants one to two weeks to germinate and a few weeks to grow before transplanting them outside four to six weeks before the last frost date. Start seeds inside in late summer and transplant seedlings outdoors in the early fall in mild climates to enjoy a winter harvest.
When you’re ready to transplant seedlings, grab your garden gloves and a trowel. Simply dig a hole in your prepared bed just a little bigger than the pot in which your seedling is growing. Carefully remove the plant from its pot and transfer it into the hole. Fill in the space around the roots with fresh soil.
Plenty of Sunshine
Broccoli needs plenty of bright sunlight. Place your raised beds in a location where they receive at least six to eight hours of direct sunlight each day. Full sun is ideal for cruciferous vegetables. With less than full sun, your plants will lack vigor, but you might still harvest a few heads, they just won’t be as full or large as those grown in full sun.
Water Well
Water any newly transplanted broccoli every day to help the roots become established in their new homes. After that, water your plants every three or four days, unless you receive enough natural rainfall to keep the soil slightly moist.
During head development, water more frequently, but don’t allow the soil to stay wet. Water your plants at the base rather than sprinkling the leaves and heads with water. This ensures that the water gets to the roots where it’s needed and doesn’t attract mildew and other fungal infections to the leaves.
Mulch
Mulching helps protect the shallow roots, helps retain moisture, and helps control fluctuations in soil temperature. Mulch also prevents weeds from taking over your raised beds.
You won’t need a thick layer of mulch, but your plants will probably appreciate a thin layer of mulch. Use an organic mulch of biodegradable materials, such as compost, chopped leaf mulch, or a thin layer of small wood chips of bark mulch.
Fertilize
Broccoli is a somewhat heavy feeder. If you want large, robust plants with big heads, you’ll need cool weather, sun, space, and fertilizer. About three to four weeks after transplanting your seedlings, apply a side dressing of nitrogen-rich vegetable fertilizer around your plants.
Apply another dose of fertilizer when the flower heads start to form. Follow the directions for application on the specific product you use, and be careful not to over-fertilize your plants.
Companion Plantings
Companion planting is a great way to both attract beneficial insects and repel insect pests that can damage your crop. Broccoli has a shallow root system, so take care when digging around your plants because you might accidentally damage the roots. It’s best to transplant your companion plants and broccoli at the same time so they can grow together and you won’t need to disturb the roots any more than necessary.
Some great companion plants include other cool-season vegetables like green onions, lettuce, spinach, and Swiss chard. Some aromatic herbs that grow well as companions include basil, dill, Rosemary, sage, and thyme. If you prefer flower companions, try geraniums or nasturtiums, either of which can be started from seed after the danger of frost has passed.
Protect from Bugs
Unfortunately, lots of insect pests love to feast on broccoli. Watch for some of these nasty invaders and remove them promptly before they multiply out of control. The best pest control will be a combination of crop rotation, companion plantings, and proactive protection from pests.
Rotate with other non-brassica crops that won’t harbor the same pests. You can also rotate with cover crops. Broccoli is a heavy feeder and quickly depletes the nutrients in the soil, while cover crops, such as crimson clover, help enrich the soil, making a great in-between crop to help refresh the soil during the off-season. Healthy plants are more resilient to insect pests.
Another way to keep bugs away is to use floating row covers. These lightweight plant covers provide a very effective physical barrier between your plants and the bugs that want to eat and lay their eggs on them. As long as you’re able to keep the floating row cover on, it will provide excellent protection from many of the most common insect pests.
Cabbage Worms
These green caterpillars are the large of the cabbage white butterfly. They devour any above-ground part of your broccoli plant, leaving the leaves riddled with holes, and the flowerheads full of … caterpillars. There are a few methods to try to keep these pests off your plants. Try hand picking them, using floating row covers, attracting beneficial predatory insects, neem oil, or BT spray.
Flea Beetles
Flea beetles are shiny black beetles that feast on many types of garden vegetables. The larvae feed on roots while the adults prefer to munch holes in the leaves. Protect your plants with floating row covers, attract predatory insects to eat them, or try deterring them by planting strongly scented leafy plants such as mint nearby.
Aphids
These pesky insect pests are ubiquitous in the garden. Aphids are most common on young plants although you will also see them occasionally on older plants. You can try to prevent and deter aphids by welcoming beneficial insects to your garden. If you see these small, soft-bodied insects starting to cluster on the leaves of your plants, spray them with jets of water to dislodge them and disturb their feeding. Do this every day or two and the aphids shouldn’t cause any severe damage.
Harvesting
You’ll know it’s almost time to harvest when you see the dense flowerheads forming in the center of the plant. Keep a close eye on the plant when the flowerheads are forming because you’ll want to harvest at just the right time. Ideally, you will harvest your broccoli heads sometime after they have reached their full size, but while the little flower buds are still tightly closed. If you see any sign that the tiny greenish-yellow flowers are starting to open, harvest them immediately.
Use a sharp, clean knife to slice off the main head, or heads. Keep the rest of the plant intact, however, because smaller side shoots will usually form after the main harvest. These secondary shoots won’t be as large as the first heads, but they’ll be every bit as tasty. Again, you’ll want to harvest these right before the flowers start to open. Any time the heads look fully formed, they can be harvested. There’s no harm in harvesting a little early.
Enjoy your Veggies!
If you already love broccoli, you probably have your favorite ways to prepare it. I like to cut the larger heads into smaller “trees” and steam them for a few minutes until they just begin to turn bright green. At this point, they are still firm but not crunchy.
Any broccoli that you don’t cook and consume immediately can be stored. Keep freshly harvested, raw broccoli in an airtight bag in the crisper drawer of your refrigerator for up to a week. You can also freeze them for longer storage. Trim them into manageable chunks and boil for two or three minutes. Immediately plunge them in iced water and allow them to cool for a few more minutes. Dry the chunks on a towel and lay them in a single layer in your freezer until they freeze and solidify. Then, store them in a freezer bag for several months.
Final Thoughts
If you’re a fan of broccoli, it’s exciting to know that you can grow your own. You’ll need plenty of sunshine, cool weather, and some nutrient-rich soil. Fortunately, if you have just a little space for a garden, you can create ideal growing conditions with raised beds. In fact, raised bed gardening is highly versatile and immensely rewarding. The best part, of course, is harvesting your own fresh broccoli. Enjoy this tasty, nutrient-packed vegetable during the fall or spring to help extend your gardening season beyond the typical mid-summer peak.