Starting Broccoli Indoors: A Step-by-Step Guide

Starting Broccoli Indoors
Starting Broccoli Indoors: A Step-by-Step Guide –

Broccoli is part of the Brassica family and one of the most popular and tasty vegetables grown at home. Most importantly, it can be harvested as often as every two weeks, making it an excellent home crop. Like many other gardeners, you might have thought about starting broccoli indoors.

Apart from being a rich source of vitamins, minerals, and antioxidants, broccoli reduces the risk of cancer, improves bone and skin health, boosts immune health, aids digestion, and reduces the risk of diabetes. Among many vegetables that can be grown indoors, broccoli is one of the most preferred vegetables to grow indoors.

So, if you love growing vegetables indoors, the idea of starting broccoli indoors will sound good to you. It might get a little bit tricky to grow broccoli indoors when you are a beginner. But following some basic guidelines and tips will surely help you out.

See also: Can You Grow Tomatoes In Indirect Sunlight: Here’s The Truth!

Broccoli Characteristics 

GenusBrassica oleracea var. botrytis
Common NameBroccoli, Calabrese, or Sprouting Broccoli
FamilyBrassicaceae Family
Lifecycle– Annual
– Biennial
Soil DrainageRequires well-drained soil with plentiful and consistent moisture
Light requirements Thrive in full sun, but it can also tolerate light shade, resulting in slow maturity.
pH requirements – pH 6.0 to 7.5.
– But can also tolerate slightly alkaline soil.
Propagation Propagate by seed
Maintenance Broccoli plants are relatively difficult because they require good soil, need to be planted at the right time, and protection from pests.
Height2 to 3 feet (0.61 to 0.92 cm)
Spread2 to 3 feet (0.61 to 0.92 cm)
Flower colorGenerally yellow
Broccoli bloom time– Early fall
– Mid-fall
– Early summer
– Mid-summer
– Late summer
Germination temperature45 F to 85 F 
Pests– Cabbageworms
– Flea beetles
– Cabbage root maggot
– Cabbage aphids
– Cutworms
– Slugs and snails
USDA Plant Hardiness Zone2 to 11 
Starting Broccoli Indoors: A Step-by-Step Guide –

1- Varieties of Broccoli

Many varieties of broccoli exist that grow at different, and some are best for fall crops. Pick types depending on their maturity dates to spread out your harvest. In addition, some varieties of broccoli tolerate heat and are best for summer harvests.

Recommended Broccoli Plants To Grow (1):

  • Green Comet has 55 days to harvest and is heat tolerant
  • Cruiser has 58 days to harvest, offers a high yield, and grows well in dry conditions
  • Green Goliath has 60 days to harvest, thrive in summer, spring, or fall, and tolerate extreme conditions. 

2- When To Start Broccoli Indoors?

Now when you should start growing broccoli indoors or how early do you start broccoli indoors? If you want to grow in spring, then you should start seeds 7 to 9 weeks before the average last frost date and keep the soil warm (about 75 F) until your broccoli germination.

And if it is a fall crop you want to harvest, then you should start seed indoors about 10 to 12 weeks before the first fall frost.

Then maintain broccoli plants around 60 F under direct sun, so plants don’t get leggy.

3- Starting Broccoli Indoors: Sowing The Seeds

First, you have to prepare your pot or any other container you want to grow broccoli in. Whatever pot or container you choose, make sure that it can provide at least 3 inches of depth for root growth.

Moreover, punch holes in the bottom to provide good drainage, without which water will keep collecting around the roots and it can damage the plant. Now you have to prepare a soilless potting mix, as it is weed-free and promotes fast growth.

First put the mix in a container other than you want to grow broccoli in, and then add water to it and make it damp. Now transfer this mix into the pot you want to start broccoli in and fill it up to half an inch from the top.

Give it gentle taps, it would make your mix firm. Now you need to make furrows in your pots, using a pencil. In each pot, the furrow should be half an inch deep and an inch long.

Sow the seeds in these furrows and cover them with the remaining mix. Gently press them down too. For your convenience, you should name each pot with the variety of broccoli you have sowed in it, and also with the sowing date.

Use transparent plastic wraps to cover your pots, it would help in retaining the moisture. In order to promote fast germination, place the tray of the pots in a warm location.

See also: How Much Light Does Lettuce Really Need to Grow Indoors (This Much!)

4- Exposing The Seedlings To Bright Light

Up till now, starting broccoli indoors might seem difficult but it is too beneficial to ignore. After you have planted the seeds, you could expect the formation of the first leaves between four to eight days.

And when you spot the first leaves, remove the plastic wraps from the pots. Expose these seedlings to bright light now, as it makes them strong.

5- Taking care of the seedlings

You need to take great care of your seedlings because starting broccoli indoors will seem meaningless and fruitless if you take it lightly. Follow the following tips for taking care of broccoli seedlings.

  • Don’t expose the seedlings to high temperatures. It can make the seedlings soft.
  • It is recommended that you keep them in a cool daytime environment i.e. between 60-65oF
  • At night, they need to be kept at a temperature of less than 10oF.
  • Water them gently, you can end up disturbing the roots otherwise.
  • Remove the weaker seedlings by using a small pair of scissors and thus make the seedlings thin, gradually.
  • There should be only one seedling remaining in each pot when the plants have reached a height of two inches.

6- Hardening Off The Seedlings

It means to stop applying fertilizer two weeks before the transplantation of your seedlings. The seedlings should be in a cold and well-ventilated frame one week before the hardening process.

Keep the seedlings under some shade to prevent them from the blazing sun of the afternoon. And at night, you could either bring them indoors or cover them from frost. The amount of heat and cold that the seedlings are exposed to every day should be increased gradually.

Don’t water them too often, rather water them only when you see the surface of the soil has started to dry. And if you are wondering “How big should broccoli be before transplanting?” then it is to tell you that when the seedlings are 4-6 inches tall, you can transplant them. 

See also: What Do Need to Start Growing Green Beans Indoors?

7- Harvesting

The trickiest thing in growing broccoli is to know when you should harvest them. The main sign indicating the harvesting of broccoli is a tight head that is 4-7 inches long and has large dense flower buds. Apart from that, for the best understating of “when to pull broccoli plants?” follow the tips mentioned below:

  • If the main broccoli head stops growing, harvest it.
  • Broccoli heads are ready to be harvested when they are deep green and have buds that are small and tightly packed.
  • You need to harvest broccoli immediately if the buds begin to open.
  • If you see broccoli starting to flower or turning yellow, harvest it on an immediate basis.
  • When the main head is harvested, the side shoots continue to grow.
  • When the side shoots reach their firmness and ideal color, harvest them.

What Vegetables Should Not Be Started Indoors?

Though you have fun growing vegetables indoors, you should generally know what vegetables you shouldn’t grow indoors. It includes:

  • Carrots
  • Poppies
  • Squash
  • Beets
  • Turnips
  • Radishes
  • Peas and Beans

See also: Gardening Tools Every Gardener Should Own

In Conclusion

Overall, starting broccoli indoors is not as tricky as it might seem to be. By growing them indoors with some proper care you can enjoy their health benefits and can have fun too.

Make sure that you are following all the methods with proper concentration to get the desired results. 


Hello friends, I am Altiné. I am SO excited you are here! I am the guy behind Plants Heaven is a blog that shares information about preparing, creating, and maintaining gardens in and out of your home, regardless of where you live. My goal is to help you learn to love gardening and reap the benefits that come with it. I am still learning; therefore, the information I share on this site may not always be “expert” advice or information. But, I do my VERY best to make sure the information shared on this blog is both accurate and helpful.

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Broccoli is one of the members of the Brassica family and one of the most popular and tasty vegetables grown at home. It can be harvested as often as every two weeks, making it an excellent home crop. Like many other gardeners, you might have thought about starting broccoli indoors.