How to Grow Broccoli Raab in Containers

Although identified by different names depending on your location, Broccoli Raab, Broccoli Rabe and Rapini all refer to one species of the Mustard Family. Scientifically classified as Brassica rapa, Broccoli Raab is characterized by its serrated leaf growth and small broccoli-like florets. The pungent leaves and flavorsome florets are a well known staple in Italian cuisine, and for most, are considered a delicacy. Having never tried the flavors of this cool season crop, I figured it was about time! In this post, I'll discuss how to grow Broccoli Raab in containers.

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Basic Necessities to Grow Broccoli Raab - 

While, I haven't grown broccoli raab in particular, I have successfully grown several species of the Brassica family in my indoor container garden. My successes with Mustard, Cabbage and Flowering Kale serve as an "informational backbone" in which I've formulated the basic necessities for growing broccoli rabe.

• Fertile, Well Draining Soil - Like many other Brassicas available for cultivation, Broccoli Raab also exhibits rapid growth development. Generally speaking, broccoli raab is ready to harvest in 45 days. In order to maintain the nutritional requirements of such a growth pattern, an extremely fertile and well draining soil must be used in planters. For my container broccoli raab plants, a 3:1 ratio of Roots Organic 707 potting soil and homemade compost were utilized to fill the container.

• Full Sun, Part Shade - To sustain the rapid growth of broccoli raab, full sun should be offered whenever possible. In cool climates where Broccoli Raab will not be exposed to intense afternoon heat, more full sun may be offered. In areas that receive a hot and intense afternoon sun, shading broccoli raab plants is recommended. In either case, broccoli raab will do best with at least 6-8 hours of  direct sunlight daily.

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Germinating Broccoli Raab Seed - 

Honestly, broccoli raab seeds are the easiest and fastest to germinate seeds that most gardeners will ever come across. I was even a bit surprised to see that several of the seeds I planted had germinated within a 24 hour period. Now that's pretty fast! Here's a look at how to start your seeds:

Broccoli Raab Plants

1. Begin planting broccoli raab seeds six weeks before the average last frost in your area.
2. Start seeds in a fine potting soil with good water retention. Plant the seeds to a depth of 1/4-1/2 inch and maintain consistent soil moisture. Using a seed tray with humidity dome, as I did, will keep the soil warmer and the air a bit more humid. This creates a better germination environment.
3. Keeping the soil moist, but not over watered, the broccoli raab seeds should germinate in an average of 2-8 days. 
4. Once sprouted, supply seedlings with adequate light. A south facing windowsill or grow lights are ideal. I kept mine inside under fluorescent lighting for 16 hours a day during the initial seedling stage.
5. Keep the seedlings watered for the next couple of weeks. 

Transplanting and Hardening Off - 

At two weeks from seed, the broccoli raab will have reached a height of a couple inches and should be working on a couple sets of leaves. At this height, it is a good time to transfer the seedlings into their final container for hardening off.

Growing Broccoli Raab. 

1. Select a container to transplant the broccoli raab seedlings into. Fill the container with your potting soil mix and gently pat it down. For my final container, I've chosen a 3.3 gallon rectangle planter measuring 16"x7"x7".
2. Dig holes according to the number of broccoli raab transplants you wish to plant in your pot. Keep in mind that broccoli raab should be spaced at least one inch from the container wall and 4-6 inches from each other to prevent crowding. 
3. When the holes are dug, begin the process of gently transferring each broccoli raab seedling into their final positions. When the transplants are in the soil, gently push down around them and water in well. 
4. Keep the newly transferred plants indoors for the next couple of days while they grab root in the soil. Continue to provide light during this time. 
5. At this point in the overall timeline, it should be about a month before the average last frost. Now, the broccoli raab plants may begin the transition from indoors to out. Harden off the plants by placing them outside for increasing amounts of time each day, taking them in after each visit outdoors. After a period of 6-9 days, the broccoli raab plants should be fine to remain outdoors. 

*If temperatures fall, or will fall below 40°F, take the broccoli raab plants indoors. While in-ground broccoli raab plants may be able to survive a light frost, container grown specimens normally don't fair as well.

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Watering and Fertilizing Broccoli Raab - 

Once the planter containing your broccoli raab is established outdoors in a sunny area, there's not much else that you really need to do but water and wait! Below I've included some criteria that I follow for my own Broccoli Raab plants:

• Watering: The broccoli raab plants need average water requirements. I water every other two days, or once the top 3/4" of the soil has dried. You may need to water every other day if you reside in a hotter climate.

• Fertilizing: Raab plants are nitrogen hungry, so a home brewed compost tea is given to the plants once a week. 

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Other Key Tidbits - 

• When germinating and growing seedlings indoors, try to keep temperatures comparable to those outdoors. Seedlings grown for two weeks indoors at 75°F, only to be transferred outdoors to temperatures in the 50's, will be much more prone to bolt and produce poorly. 

• Staggered planting is best to maximize production and room in containers. I obviously let this one slip my mind! I'll be planting broccoli raab in a staggered formation for the fall, but for now, I'll have to manage with a straight row. 

• In warmer climates, it's essential not to expose the broccoli raab plants to intense sunlight with temperatures that increase above 75°F. In these hot temperatures, raab plants will signal for production to stop and for bolting to commence. 

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Final Word - 

Hopefully, I've helped clear up a lot in terms of growing broccoli raab in containers. I look forward to harvesting my plants, and will post a harvesting guide when the time comes. Until then, keep checking back to see how their growing! Thanks for reading.