When summer ends, and the days turn shorter, many gardeners know that its time to start planting broccoli. Broccoli is a cool-weather vegetable that thrives in very early spring and late fall. It’s one of America’s favorite vegetables because it’s full of vitamins and minerals while still being low in calories. It also provides a healthy dose of fiber without adding empty fats or carbohydrates to your diet.
Planting broccoli is easier than you think, and you can grow this veggie in the ground and in containers. This means that even those with a tiny garden space can make some room for broccoli. And because it’s a winter vegetable, you’ll still have something to grow when the rest of your garden is fallow following summer crops.
When to Start Planting Broccoli
If you garden regularly, you probably already know your growing and hardiness zone. If not, you can go to the US Department of Agriculture (USDA) website for a map that provides that information. Once you know your location and zone, you’ll be better able to choose plants for your garden. Most plants and seeds indicate their hardiness zone. For planting broccoli, you’ll note that most vegetable seeds packets provide a time frame for when to plant them on the back. You may even see that they give one time-frame for starting seedlings indoors and another recommendation for transplanting those seedlings.
Planting broccoli in the fall
Fall is one of the most popular times for planting broccoli because of its relatively predictable rainfall. Depending on where you live, spring can bring a late freeze or intermittent rain storms that destroy tender seedlings.
You can calculate when to start planting broccoli by figuring out when the first freeze will likely occur. You want to give your broccoli about 85 to 100 days to grow before any freeze. So, if you’re planting seeds directly into the ground, sow during this time frame to give your broccoli time to mature.
If you’re planting broccoli seedlings, make sure they’re mature enough to transplant. You can start your seeds indoors and then transplant them into the ground in about four to six weeks. If you purchased seedlings, make sure that they have at least four or five “true leaves” before transplanting them. True leaves are the leaves that grow after the first leaves of the sprouting seed. They often look very different from the first leaves, so it’s often easy to check their maturity. With well-grown seedlings, you can put them in the ground about 75 to 90 days before your first predicted frost.
One way to estimate your first frost date is with a handy tool from The Farmer’s Almanac online. Type in your zip code, and you’ll get an estimate of your first and last likely frost dates based on a 10-year history of your region. The data used to calculate these dates comes from the NOAA National Center for Environmental Information.
Planting broccoli in the spring
Some varieties of broccoli can germinate in soil temperatures as low as 40 degrees Fahrenheit. For that reason, many gardeners also choose to plant broccoli in the spring. For best results, you’ll want to start your own seedlings in the winter, about two or three weeks after your last frost. When soil temperatures rise enough to work the soil, plant your seedlings just slightly below where they were in the pot.
Why timing is so important when planting broccoli
Broccoli requires cool weather to produce the heads at the right time during the plant’s development. If your broccoli becomes exposed to freezing temperatures too soon, the heads will form too early. They’ll be small and rather unimpressive. If it gets too hot, your broccoli will bloom, and instead of forming edible heads, it will try to produce seeds by "bolting."
Broccoli is one of the fussiest vegetables when it comes to temperature. The seeds germinate best in soil that measures 70 to 80 degrees Fahrenheit. However, if the soil temperature goes over 75 degrees Fahrenheit after the heads have started to form, it will bolt and develop flowers. At that point, your veggies have failed to develop, and you won't have much of a harvest. You could probably collect and save the seeds, but you won't get big, delicious heads of broccoli florets.
How to Start Planting Broccoli
You can start broccoli from seed or purchase seedlings from your local garden center. Purchasing seedlings allows you to get a head start on your winter garden, but you need to make sure you’re planting broccoli at the right time of year for your region.
Most local nurseries carry plants that do well in your growing zone and stock seedlings according to the season. But unfortunately, many big box home improvement centers and department stores often don’t follow the recommendations for their locations. This is because they often order from a central location that may be hundreds of miles and two or three growing zones from where you shop. So, make sure that if you shop in these types of stores that you choose your seedlings carefully. Make sure the variety you purchase is actually within your planting time-frame and does well under your local climate conditions.
Where to Start Planting Broccoli
Luckily, you can grow your broccoli either in the ground or in a container. While container gardening requires some initial investment in potting soil and pots, it also allows you the opportunity to extend your growing season to some degree. If you’re a bit late planting your broccoli and get an unexpected freeze, you can move them indoors if necessary. Sometimes, just moving them close to a sunny exterior wall helps protect them from a freeze, especially if you cover them overnight.
Whether you choose the garden ground or decide that planting broccoli in a container is the best way to go, you’ll need to locate your plants where they’ll receive at least four to six hours of sunlight during the day. You’ll also need to make sure you can keep them watered conveniently.
Planting broccoli and trying to grow it to maturity indoors is possible but can prove difficult. You’ll need an area that gets at least six hours of direct light from the sun. Barring that, you can install grow lights to give them 12 hours or more of artificial light every day. You’ll also need plenty of space for your plants. You’ll need pots that provide at least 8 to 12 inches of depth with diameters of 12 to 15 inches.
Preparing your garden for planting broccoli
This vegetable prefers rich, moist soil, so preparing your garden soil is important when planting broccoli. Add a layer of compost and dig well into your garden. Organic matter improves your soil quality, making it lighter and releases nutrients back into the soil. Broccoli also prefers slightly acidic soil, so you may want to purchase a soil test kit or contact your local extension office for assistance.
Because it requires plenty of water, consider adding a drip irrigation system or slow watering bottle if you're planting in the ground. You may need to water container broccoli plants every day or every other day if you have dry falls and winters.
Pay attention to spacing when planting broccoli
Your broccoli heads need plenty of space to grow when you plant them in the ground. Depending on when you plan to harvest them, give them at least of foot or two between plants. If you provide at least 24 inches between plants, you can often “side harvest” your broccoli after you remove the main stalk head. That way, you'll get better production. If planting in several rows, plant for three feet between each.
Caring for Your Broccoli plants
After you’re done planting broccoli in your garden, you’ll need to care for them properly. Broccoli has a few special requirements that might surprise you.
As mentioned above, broccoli requires regular watering, even when mature. Make sure you provide at least 2 to 3 inches of water for your plants throughout the week. Regular moisture results in more tender stems. Dry spells mean tough stems that are no fun to eat, so make sure it receives consistent moisture.
Also, when possible, water under the plant instead of down over the foliage. While you can’t really tell the rain not to fall on them, broccoli heads develop better when they stay dry. So, when providing a supplemental watering, avoid getting any heads wet.
Broccoli forms surprisingly shallow roots. For that reason, avoid pulling up any weeds that develop around your plants to avoid damaging the roots. Instead, mulch around the plants to control weeds. You can use bark or straw but remember not to use chemically treated mulch around edibles. A thick layer of mulch also helps keep the soil temperature cooler, which results in a sweeter broccoli head.
Wait at least three weeks after transplanting to feed your broccoli. Compost or fish emulsion are both safe and effective fertilizers for your plants. Your broccoli needs most of its nutrients before the heads start forming, so ensure that you use good quality soil and provide regular fertilizer after your seedlings have established themselves.
Cabbageworms and cabbage loopers leave tiny holes in your broccoli leaves, but Bacillus thuringiensis, a natural bacterial pesticide can keep them at bay.
Downy mildew is a fungus that covers leaves with a powdery, white film. Although it’s not fatal, it can block the sunlight and retard your plant’s growth. Keep the leaves dry if possible, to prevent fungal infections. Ensuring that there is plenty of space between plants improves air circulation, which helps keep them drier. We also use milk, diluted about half and half with water, and spray the tops and bottoms of the leaves every 10 to 14 days when the weather is sunny. We also use it on our fall tomatoes, which simply thrive thanks to the added calcium.
Nitrogen deficiency will cause your broccoli leaves to turn yellow. If the yellow continues to the upper leaves, add a high nitrogen, low phosphorus fertilizer.
Harvesting Your Broccoli Plants
Once the head is fully formed on your broccoli, it's ready for you to harvest. The heads should be firm and tightly formed right before they flower. They will be about 4 to 7 inches in diameter when ready. However, if you do see the yellow petals of the flowers start to form, harvest the heads immediately, regardless of their size.
Cut the head away from the plant, with at least six inches of the stem still attached. Cut the main stalk at an angle, since this helps your broccoli plant form side shoots, which you can harvest as they develop.
As long as the weather complies, you can harvest side shoots that form around the main head. If temperatures allow, you can continue to harvest the side shoots for weeks, even months. In warmer climates with few or no hard freezes, you’ll be able to harvest a fall crop all winter long by using a row cover or cold frame.
Time for Planting Broccoli!
Many gardeners feel down when the summer ends, but many vegetables are perfect for planting in the fall. Broccoli and other cabbage family vegetables grow beautifully in the colder months and will keep for a long time. Once harvested, you can blanch your broccoli in boiling water and then freeze it for up to a year.
Fall is the right time for planting broccoli, cabbages, Brussels sprouts, cauliflower, and celery. You can also plant many leafy vegetables like lettuce, spinach, and kale. So, your gardening fun doesn’t have to end just because summer is over. Plan some time to prepare your soil between summer crops and fall planting and enjoy more than just pumpkins now that autumn has fallen.