Broccoli can flourish in containers—just be sure to choose your pots carefully. Broccoli spreads to 2 feet or more, so plant one per 5-gallon container, or three per a 15-gallon container, at minimum. Because broccoli like to be cool, avoid black pots and try to position the containers so the broccoli is in part shade and the pot is in full shade. you don’t want your broccoli container to go past 80 degrees F.
The secret to successfully growing broccoli in containers is to keep them cool, fertilize regularly, have good light, a comfortable temperature, healthy soil, and consistent water. Hit all those targets and your container-grown broccoli will be just fine!
Broccoli needs six to eight hours of sunlight each day to flourish. The light should be direct, not filtered. However, broccoli thrives in cool temperatures; if your temperatures regularly stay above 80 degrees F in the early summer or early fall, you’ll want to place your containers in an area where your broccoli plants get some shade in the middle of the day or be prepared to move them into the shade each day.
Keep broccoli well-watered, especially during dry periods. Typically, the plants need 1 to 1 1/2 inches of water per week. If you’re growing broccoli in a container, make sure the container has adequate drainage, so the roots are never standing in water.
Avoid watering broccoli from the top as getting the heads wet encourages rot. Check the soil’s moisture level periodically. You can use something as basic as a pencil to poke down into the soil to see where the moisture is.
For happy, healthy broccoli, use a commercial soil mix developed for gardening. Some gardeners prefer to use soil from their garden, but that can introduce any number of pathogens to your young plants.
Feed your broccoli with a low nitrogen fertilizer three weeks after transplanting seedlings. Fertilize again when the plants are 6 to 8 inches tall, 12 to 15 inches tall, and then when the buds first form.