Broccoli is a member of the Brassica genus in the cabbage family. It produces florets of edible flower buds known as heads or crowns. This vegetable has been cultivated for centuries yielding countless varieties.
This article will cover everything you need to know about broccoli. This includes detailed care guidelines, how to plant it, and what pests to watch out for. Let’s start with a brief history of where broccoli came from.
History of Broccoli
Broccoli is a man-made crop that has been around since 600 BC. Romans initially cultivated it in the Mediterranean region. Italians perfected the crop before it was spread across Europe by the 18th century[1].
In the mid-20th century, the U.S. and Japan began developing superior varieties of broccoli. These hybrids grow quicker and produce more heads. Many are also resistant to various environmental conditions.
Broccoli Plant Care
Broccoli is relatively easy to grow in the garden and can be planted in spring or fall. While it doesn’t do well in hot weather, it makes a wonderful early or late-season crop.
The most important factors for successfully growing broccoli are temperature and watering. Too much heat leads to poor yields. Incorrect watering can cause broccoli to taste bitter. Below are all the key ingredients to producing a bountiful broccoli harvest.
Soil
Soil should have a pH between 6 and 6.8. Loamy soils are ideal but other soil types will work with the right amendments.
Add organic matter to clayey soils to improve drainage. Compost can also improve sandy soils by increasing moisture retention and nutrients.
Watering
Broccoli plants need between 1 and 1.5 inches of water each week. Water the soil deeply once a week in the absence of rain. Sandy soils will need to be watered more often to keep them from drying out. Mix compost into heavy clay soils to improve drainage.
Keeping consistent soil moisture will help you avoid water stress. Water stress can lead to underdeveloped, bitter broccoli heads. Avoid getting the florets wet when watering which could lead to rot.
Lighting
Most vegetables need lots of sunlight, but does broccoli need full sun? Yes, you should make sure your broccoli will get at least 6 to 8 hours of sunlight per day.
Opt for the morning sun. Harsh afternoon sun may cause flowers and seeds to develop too early known as bolting.
Humidity & Temperature
Broccoli is a cool-weather plant that can grow when temperatures are 40 to 95 degrees Fahrenheit. Ideal temperatures for growth are between 65 to 70 degrees Fahrenheit. Prolonged temperatures above 80 degrees Fahrenheit can cause plants to bolt.
Broccoli grows in low, moderate, or high humidity conditions. When humidity is low, adequate water is essential. High humidity can lead to disease issues if plants aren’t properly spaced.
Fertilizing
Generally, a 5 percent nitrogen, 10 percent phosphorus, and 10 percent potassium (5-10-10) fertilizer is best for broccoli. Mix 1.5 to 2 pounds per 50 square feet into the soil before planting. Apply another pound per 50 square feet each month as the plants grow.
Applying the correct amount of fertilizer is critical. Too much or too few nutrients can negatively impact the plant’s health, growth, and taste. Have your soil tested to determine the correct amount of fertilizer to apply.
Diseases & Pests
Several diseases and pests can impact broccoli. The best way to prevent them is to plant and care for your broccoli correctly.
Below is a table with the most common insects and diseases that impact broccoli. We’ve included the signs and symptoms they cause to help you identify and stop them quickly.
| Pest Name | Signs & Symptoms |
| Alternaria | A fungus that causes leaves to develop spots and crowns to rot. |
| Aphid | A sap-feeding insect that causes leaves to become distorted, stunted, and/or yellow. They produce sticky honeydew which can cause sooty mold to grow. |
| Black rot | A fungus that causes triangular, yellow spots along the leaf margins. Can also cause crown rot. |
| Cabbage looper | A caterpillar that feeds on the leaves, creating large holes. |
| Cabbage maggot | A fly larvae that feed on roots and can cause plants to be stunted from lack of nutrients. Severe infestations can lead to plant death. |
| Clubroot | A fungus that impacts the roots causing them to enlarge leading to stunted plants. |
| Diamondback moth | A caterpillar that feeds on the leaves, leaving large holes. They can also feed on broccoli heads. |
| Downy mildew | A fungus that causes a white to gray cottony growth on the underside of leaves. Jagged, yellow spots develop on the leaf’s surface. Leaves eventually become distorted and drop from plants. |
| Flea beetle | A beetle that feeds on leaves leaving small holes. |
Days To Maturity
On average, broccoli goes from seed to mature plant in 80 to 100 days. The variety you plant, nutrient availability, sunlight, and temperature can all impact maturation.
Harvesting
Broccoli heads are ready to harvest when the edges begin to loosen slightly. They should be around 6 to 8 inches across at this point. Cut the head off at an angle so that water doesn’t pool on the stem.
After harvesting the central head, side shoots will continue to develop and mature. Some plants will produce for a few weeks while others can produce heads for a few months.
Broccoli can be stored for about 5 days in the fridge. To prolong the shelf life, blanch it then store it in the freezer.
How To Plant Broccoli
You can plant broccoli in the spring or fall. Make sure to till the soil before planting. Seeds can either be sown outdoors or started earlier indoors and then transplanted. The ideal spacing for broccoli plants is 18 to 20 inches apart.
When directly sowing seeds outdoors, plant seeds ½ inch deep and 3 inches apart. You should only plant one seed per hole. Planting 2 seeds per hole may increase germination success. However, if both germinate you may damage the delicate roots when you remove one of them.
Once seedlings emerge and are 2 to 3 inches tall, thin them out so plants are 18 to 20 inches apart.
When planting indoors, use a seed starter tray. Place two seeds per cell ½ inch deep in good quality garden soil. Wait until seedlings have 4 to 5 leaves each before transplanting outside.
Succession planting broccoli will increase the length of the harvesting period. There are two ways to accomplish it. You can either use multiple varieties or stagger your planting dates.
If you plant multiple varieties that mature at different rates, you can plant them all at the same time. They will then produce mature heads naturally over a longer period. If you want to use the same variety, simply plant seeds every 2 to 3 weeks to stagger when they mature.
Broccoli Growing Stages
There are four main stages of broccoli growth starting with germination. The germination stage occurs from the time the seed breaks open until the first true leaves emerge. Next is the seedling stage which lasts two to four weeks.
Seedlings will develop some fine roots and smaller leaves. After about 4 weeks, broccoli will have several small leaves and start the vegetative stage. This is when the majority of leaf growth occurs and plants reach 3 feet tall by 3 feet wide.
The final stage is the maturation stage. This occurs when the broccoli heads begin to form. If temperatures are too high, this is when bolting may occur. Bolting causes the heads to flower prematurely which prevents harvesting.
Types Of Broccoli
There are dozens of types of broccoli. Some tolerate heat or cold better than others. Choose your variety based on average temperatures in your area and how quickly you want it to mature.
Below is a table with a few of the most popular varieties.
| Variety | Days to Maturity | Characteristics |
| Bonanza | 55 | Develops copious side shoots after the central head is harvested. |
| Calabrese | 58-90 | This heirloom variety is one of the most popular types. It develops large heads and many side shoots. |
| Decathlon | 100 | This heat-tolerant variety produces blue-green heads. |
| Green Goliath | 53 | Is ideal for growing in the south due to its heat tolerance. |
| Marathon | 68 | Extremely cold tolerant which makes it great for fall planting. |
| Packman | 50-73 | This variety is one of the earliest producing types. |
Broccoli Companion Plants
Plants like beets, bush beans, celery, chamomile, chard, cucumbers, onions, peppermint, potatoes, sage, spinach, radish, and rosemary grow well with broccoli. You should avoid planting cabbage, cauliflower, dill, lettuce, peppers, pole beans, strawberries, or tomatoes near broccoli.
Broccoli vs Broccolini
The main difference between broccoli and broccolini is the length of the stem and the size of the head. Broccolini is the result of broccoli and Chinese broccoli hybridizing. The stems of broccolini are more tender than broccoli stems. Broccolini is also less bitter and a bit sweeter than broccoli.
References
[1] Broccoli. (2023, January 1). In Wikipedia. https://en.wikipedia.org/wiki/Broccoli
