Growing broccoli from seed can be a bit challenging for beginners, but it’s not difficult once you learn how.
In this complete guide, I will give you all the information you need about how to grow broccoli seeds successfully, even if you’ve struggled with it in the past.
You will learn the best sowing methods to use, when to start, step-by-step planting instructions, plus seedling germination time, identification, care, repotting, transplanting, and more.
Growing Broccoli From Seed
| Days to germination | 5-10 days |
| When to start indoors | 4-6 weeks before transplanting |
| When to sow outside | 3-6 weeks before your last spring frost date |
| Days to maturity | 50-90 days (depending on the type) |
| Sun exposure | Full sun |
| Seed planting depth | ⅛ – ¼” deep |
| Spacing | 12-24″ apart |
| Soil temperature | 60-80°F |
Types To Grow
There are several different varieties of broccoli seeds that you can plant. Some types have larger heads, while others are small, but more prolific, or they mature earlier.
A few of my favorites are Di Cicco (classic heirloom), Early Heading (early to mature), Long Harvest (blend of early and late), Summer Purple (larger heads), Santee F1 Purple (small, but abundant).
Related Post: How To Care For Broccoli Plants
How Long From Seed To Harvest?
Many types of broccoli need a fairly long growing season to mature from seed to harvest, but some are much faster. Depending on the variety, it can take anywhere from 50-90 days.
That is a wide range, so it’s best to check the packet so you know what to expect from the specific variety you’re going to plant.
Tips For Planting Broccoli Seeds
You don’t need to do anything special to prepare your broccoli seeds before you sow them, but it’s important to plan ahead. Below I’ll talk about the different techniques you can use and when to start.
Broccoli Seed Starting Methods
There are 2 methods that you can use to grow your broccoli seeds: 1. starting them indoors, 2. direct sowing. The best one to use depends on where you live.
- Starting them indoors – If you’re in a cold climate with short summers like I am, then it’s best to start them indoors. Otherwise the plants might not have time to mature before fall.
- Direct sowing – But if you live in a warmer region, you can sow them directly into the garden, or you could try winter sowing them.
Related Post: 3 Seed Starting Methods That Every Gardener Should Try
When To Plant Broccoli Seeds
Start your broccoli seeds indoors 4-6 weeks before your average last frost date, or direct sow them as soon as the soil is workable in your garden in early spring.
They are cold hardy, and the seedlings won’t be harmed by a late frost. If you have mild winters, then you can sow them in the fall.
How To Plant Broccoli Seeds Step-By-Step
Though you will need a few things to start your broccoli seeds indoors, you don’t need to buy a ton of fancy equipment. Below is a list of what you need and the steps for sowing them.
Supplies Needed:
- Broccoli seeds
- Seedling flat with a lid
- Pre-moistened seed starting soil or peat pellets
- Water
- Hand trowel
- Heat mat (optional)
Step 1: Fill the trays – Fill your planting tray with a high quality seed starting mix, or use pre-moistened peat pellets if you prefer.
Step 2: Decide how many seeds to plant – If you’re using brand new seeds, then you can just plant one per hole. Otherwise, if they are old, then you may want to use 2-3 per hole.
Step 3: Plant your seeds – You can either make a shallow hole in the soil, and drop a broccoli seed into it. Or place the seed on top, and then gently press it into the soil. I find it easier to make the holes first.
Step 4: Bury the seeds – Lightly bury them, and gently press the soil down to ensure it comes into contact with the seeds. Since they are so small, you should only plant them about 1/8″ – 1/4″ deep.
Step 5: Add water – It’s best to water your trays from the bottom, so you don’t disturb the soil or displace the seeds. Simply pour water into the tray, and allow the soil to soak it up from the bottom. Dump out any that hasn’t been absorbed after 20 minutes.
Step 6: Cover the tray – Place the plastic lid on the top of the tray to ensure the soil doesn’t dry out during germination. Then move it in a warm location, or put it on top of a heat mat.
Broccoli Seed Germination Time
On average it takes about 5-10 days for broccoli seeds to germinate and for the seedlings to start popping out of the soil.
If you planted them indoors, and you want them to germinate faster, put the trays on a heat mat to speed things up.
What Do Broccoli Seedlings Look Like?
When they first sprout, baby broccoli seedlings will have only two leaves. Those are called “seed leaves”, and they look like two fat hearts on either side of the stem.
All of the ones that grow after that are called the “true leaves”, and those look like tiny mature ones. They usually start to form within a few days after the seed leaves have opened.
How To Care For Broccoli Seedlings
Once your seeds have sprouted, it’s important to give your broccoli seedlings the proper care so they will grow strong and healthy. Below I’ve included some detailed tips. You can also learn more about general seedling care here.
Light
Broccoli seedlings need a lot of light, or they will quickly stretch and grow leggy. A sunny window isn’t going to be enough for them.
So add a grow light and hang it a few inches above your trays at all times. Then use an outlet timer to automatically run them for 14-16 hours per day.
Related Post: A Beginner’s Guide To Grow Lights For Seedlings
Water
They won’t grow well if the soil is too dry or wet, and improper watering can lead to problems down the road. You should keep it evenly moist, but never wet or saturated.
So check daily, and add more water as necessary. A moisture gauge can help you get it right.
Air Circulation
After most of the seeds in the tray germinate, it’s a good idea to give them some fresh air. This will help prevent mold growth, and strengthen the seedlings.
Start by propping the lid open for a few days, then eventually removing it all together. Just be mindful that once the lid is off, the soil will dry out faster. So check often to make sure it’s not drying out too much.
Fertilizer
Broccoli plants are heavy feeders, so fertilizing your seedlings is very important. Once they have a few sets of true leaves, start giving them a weak dose of an organic option, like liquid compost tea.
Once you move them outside, you can use fish emulsion or liquid kelp. The seedlings absolutely love these, but they can get a little stinky when you use them indoors.
Thinning
If you planted more than one broccoli seed per cell or pellet, or you sowed them too close together, then you’ll need to thin your seedlings after they start growing.
Otherwise they’ll crowd each other out, which will stunt their growth and prevent head formation. So, once they’re a few inches tall, choose the strongest one, and thin the rest.
Potting Up
When they are twice as tall as the tray, you should repot your broccoli seedlings into larger containers. That way they will have plenty of room to grow.
I like to use plantable pots to make transplanting them easier. But you could use small plastic nursery pots instead, if you prefer. They are reusable, which is nice.
Transplanting
Broccoli is frost hardy, so you can transplant the seedlings into your garden 2-4 weeks before your average last frost date in the spring. If that makes you too nervous, then you can wait until after all chance of frost is gone.
But before you even think about planting them into your garden, you must harden the seedlings off to prepare them for life outside. Do not skip this step, or they may not survive.
FAQs
When broccoli seeds fail to germinate, either they were too old, or it was too wet or dry for them. They germinate best when the soil is 60-80°F, so use a thermometer probe. If they’re more than 2 years old, plant 2-3 per hole and thin them later.
You don’t need to soak your broccoli seeds before planting them, but it can help them germinate faster and more reliably. If you want to try it, simply soak them in warm water overnight before sowing them.
Adding bottom heat is a great way to speed up germination. Simply place the trays on top of a heat mat, and monitor the temperature with a soil thermometer. Ideally it should be between 60-80°F for the quickest germination time.
No, broccoli seeds do not need light to germinate.
Growing broccoli from seed is so rewarding, and fun too. Once you get the hang of it, it’s also very easy. Plus, you can grow some pretty cool varieties that you can’t find at the garden center.
If you’re tired of struggling, and want to learn how to grow any plant you want from seed, then enroll in my online Seed Starting Course. It’s a wonderful, fun, self-paced course that will teach you everything you need to know to easily grow your own seedlings. Enroll and get started today!
Or, if you just need a refresher, then my Starting Seeds Indoors eBook is for you! It’s a quick-start guide that will get you planting seeds in no time.
Share your best tips for growing broccoli from seed in the comments section below.
Lara says
This is such a helpful article and comment section. I’m in NC and have started my seeds. They’re probably 2 weeks along and looking great. I’ve already thinned them, as it was really clear which was the strongest plant in each cell. It seems broccoli can be pretty fussy but I’m excited to try and learn! I have more seeds I can try to start or direct sow in late summer.
Amy Andrychowicz says
Yay, I’m so happy to hear you’re having such great success with your broccoli seeds! Congrats, and I hope they will thrive and produce well for you this summer! 🙂
Mallory says
I live in Indiana and have to replant bc my seedlings got suuuper leggy and flipped. It’s currently May 10, is it too late to start a new batch?
Amy Andrychowicz says
You might be able to get away with it in your zone, but I personally would just go buy starts at this point instead of trying to plant more seeds. Broccoli does take a while to mature and begin producing, so buying starts will ensure you have enough time to get a good harvest. Just to experiment, you could start more seeds indoors and also buy seedlings so you can see how well the plants from seeds do this late in the season.
Kristina Dulle says
I purchased broccoli sprouts from the store and wanted to grow them into full on broccoli plants instead of eating the seedlings. I’m trying to find any information on how to safely transplant the seedlings from the mass in the plastic container into something more suitable for growth. Any recommendations would be greatly appreciated 🙏
Amy Andrychowicz says
It certainly would be a fun experiment to try! It is possible pot up some of the broccoli sprouts and have them grow into full sized plants. The trick is to take great care not to damage the tiny, delicate roots and stems, or they likely won’t survive. If they are packeted tightly together, then it might be difficult to separate them. See if any of them are loose enough to easily life out, or if any fall out easily when you gently shake the whole clump. But even then, the roots may have been damaged during packaging, so it’s no guarantee they will survive. But, like I said, it’ll be a fun experiment. I would plant several for the best chance of success.
Kasey Lee says
I started growing broccoli indoors from seed over a month ago and they don’t seem to have progressed much past tiny plants. They get fertilizer, water, grow light and have ran a fan at time. They were leggy but were replanted into bigger pots and are still alive….just not getting bigger. What do I do?
Amy Andrychowicz says
If your broccoli seedlings aren’t getting any bigger, then it could either be improper watering, or they might not be warm enough. Keep the soil evenly moist at all times, it should never be wet or completely dried out. If the room is cool, you can either add a space heater, or put a heat mat under the seedlings.
Amber Kuntz says
I live in Kansas and have grown broccoli from a plant I bought at a store before, but this is my first year growing them from seed. My first batch I started indoors all died. The edges of the leaves turned brown and crispy and eventually they all just died. I had put them all in a coconut coir soil. The 2nd batch I started in a seed starting mix I bought from the store and they are all starting to do the same. It seems to start after I give them some fertilizer. I have been doing a fertilizer tea bag so maybe it is too strong? I don’t give it until after they have their first true leaves. I have a few that I think will make it, but most of them look awful. Any suggestions on what I am doing wrong?
Amy Andrychowicz says
Yes, it sounds to me like your broccoli seedlings are getting fertilizer burn. Always start with a very weak dose of fertilizer at first, about 1/4 of the regular strength at most. Then gradually work them up to full strength as they grow larger. For your damaged broccoli seedlings, I would stop fertilizing them until they get a few sets of healthy leaves. Good luck, I hope they will recover.
Nick Jones says
I have planted a lot of Broccoli which I grew from seeds I used to grow broccoli sprouts..I have a lot of plants but they seem to be flowering very quickly with small heads. Will they grow bigger and produce more heads?
Amy Andrychowicz says
Broccoli will flower quickly in warm weather, so it sounds like you may have started your seeds too late. The heads that are flowering won’t get any larger. You can just cut them off and toss them into the compost bin. Once the main head is gone, broccoli will continue to produce smaller offshoots that you can harvest all summer long.
tina says
what should I do if my broccoli is already leggie can I still plant
Amy Andrychowicz says
It depends on how leggy your broccoli seedlings are. If they are so tall and thin that they are starting to arch or fall over, then you won’t be able to save them. If they are just starting to get a little tall, but not super thin yet, then giving them more light should fix the problem.
licitujme says
Broccoli that matures during cool weather yields heads that are sweeter than broccoli harvested during other times of the year. It s best to grow broccoli in fall since spring conditions may be unpredictable.
Amy Andrychowicz says
Thanks for adding your tips about growing broccoli. Our growing season here in MN is too short to plant them in the fall. So we must grow them in spring/summer in order to get a harvest. 🙂 But fall is a great time to plant them in warmer climates for sure!
m. cooley says
Hi
Broccoli planting is awesome. My question is: I have these plants now going into the second year. They are thick and strong and produce small babies along the sides. Should I have pulled them up and start over? Can the leaves be chopped up for soup and are the leaves nutritious? I live on the coast of B.C. I learned to plant EARLY! They bolted for sure but produced tonnes of seed for the sprouter. Sprouted broccoli seeds are very very nutritious. No one is talking about that.
Amy Andrychowicz says
As long as your broccoli plant is still producing side shoots, then you can keep it growing. There’s no need to pull it as long as it keeps producing. Yes, the leaves are edible. The smaller the leaves, the more tender they will be. You can use them just as you would use kale (in soups, smoothies, etc). Awesome that your broccoli plant produces seeds, very cool! And you’re right, sprouting broccoli seeds is delicious and nutritious! 🙂
Marly says
I live in Las Vegas and planted broccoli seeds 3/17. It’s now 5/13 and even though the plants look fine, they got too hot and they’re flowering. So, if you live in a hot place, plant sooner than 3/17.
The worst part is that my husband bought the seeds around January, and I didn’t realize they were a cool season crop- because I didn’t read the package. I could have planted much sooner & had a crop! Looking forward to fall to try again.
Amy Andrychowicz says
Oh bummer! Yes, in Las Vegas, you should be planting your broccoli seeds in the fall, and growing it through the winter during the coolest months of the year. Good luck!
michael says
Never grew any vegetables before broccoli is just one I’m growing indoors. Started seeds on may 12th, it is now may 20th, the stems are about 2 inches in height and drooping over is this normal, what should I do?
Amy Andrychowicz says
When you say the seedlings are drooping over…do you mean they are falling over at the base of the stem and dying? If so, that is called damping off and there’s nothing you can do for the seedlings that already have it. Next time, be sure to disinfect your seed trays before you use them again.
Otherwise, if your broccoli seedlings are growing leggy and flopping over, that means they aren’t getting enough light, and you need to add grow lights.
kairochi says
Is brocoli suitable with peat soil?
Amy Andrychowicz says
Broccoli grows well in a slightly acidic soil, which is what a peat soil would be. But, they are heavy feeders and need fertile soil as well, so I would recommend amending your soil with compost or other organic soil amendments.
kenneth says
can you recommend the required pesticides if my broccoli plant is attacked
Amy Andrychowicz says
It depends on the pest. Cabbage worms are the most common broccoli plant pest, and you can learn how to get of them here.
But definitely don’t use any type of chemical pesticide on your broccoli plants, check out this post for some help with controlling garden pests organically… Natural Pest Control Remedies For Your Garden