How to Grow Broccoli in SW Michigan

Gardening in Michigan

Gardening in Michigan has been one of my greatest joys due to its temperate climate, mild summers, and beautiful seasons. I have grown (and seen) some of the most beautiful and flourishing gardens here! However, with these perks come its fair share of challenges, including late frosts, short springs, and a short growing season.

Armed with the right tools, tips, and knowledge of the seasons, however, you can grow an amazing amount of delicious and healthy food, and this includes BROCCOLI!

Health Benefits of Broccoli

If not for its nutty flavor and versatility in the kitchen, broccoli should be a staple in your garden because of its powerhouse nutritional benefits! It's chocked full of vitamins, minerals, fiber and antioxidants - all great things when it comes to staying healthy and vibrant.

As with most dark green veggies, broccoli is full of vitamin C and vitamin K. In fact, one cup of raw broccoli has 135% of RDI for vitamin C (put down the orange juice, y'all!) and 116% of RDI for vitamin K, which is amazing (note: talk to your doctor about vitamin K if you're on blood thinners.)

Now you lose a fair amount of vitamin C when you cook it, but even then, cooked broccoli provides 84% of the RDI (still more than 1/2 of an orange!). And as you probably know, steaming broccoli retains the most of then nutrients.

You can read more about the health benefits of broccoli HERE, but here's a quick list of its benefits:

Contains lots of antioxidants (inhibit or neutralize cell damage)
May reduce inflammation
May protect against cancer
May help control blood sugar
May support heart health
Promotes healthy digestion & reduces constipation
May slow mental decline & support brain function
May slow the aging process
Supports a healthy immune system (hello, vitamin C & K!)
Supports dental & oral health
Promotes healthy bones & joints
Can support a healthy pregnancy
Can help protect your skin against sun damage

So with these in mind, let's go grow some broccoli!!

Categories & Varieties of Broccoli

As with most vegetables, there are several varieties of broccoli to choose from, each with its own set of features. Knowing and understanding the nuances of each variety will help you not only help you grow broccoli successfully, but extend your harvest of it as well.

Some broccoli varieties can be ready to harvest in 60 days! While others can take as long as 100 days, and you can even grow it throughout the winter. If you schedule your calendar correctly, you can be eating homegrown broccoli practically year round!

2 CATEGORIES OF BROCCOLI: Heading and Stem

Heading broccoli, as the names suggests, has a large head made up of many, tightly-woven florets attached to a thick stalk.
Stem broccoli has a thick stalk where the florets grow off of it.

4 MAIN TYPES OF BROCCOLI: Calabrese, Purple Sprouting, White Sprouting, and Broccoli Rabe

Photos courtesy of BAKERS CREEK, GARDENING KNOW HOW, GARDENER'S WORLD, & SAN DIEGO SEED COMPANY

CALABRESE: The most common type of broccoli, Calabrese originates from Calabria, Italy (where I used to live!) and is known for its large, dark green heads and tender stalks. This variety is adaptable to various growing conditions and has a delicious, mild flavor.
PURPLE SPROUTING: A variety that grows well into, if not through the winter, purple sprouting broccoli is both beautiful and prolific! It has a thinner stalk that produces many side shoots (a characteristic of some heading brassicas) of small purples heads. It's known to have a sweeter flavor and obviously provides a pretty pop of color to your garden (and dinner plate!) AND it touts the HIGHEST LEVELS of vitamin C and antioxidants of all the broccoli varieties (you can thank its purple color for that!)
WHITE SPROUTING: White sprouting broccoli seeds and plants are harder to find, but are worth the search. Their slender stalks with tiny white flowers have a milder, sweeter flavor than its purple cousin; AND the heads, stalks, and leaves are edible, making this a superb choice for the kitchen. This variety is also great for overwintering as it can survive temperatures as low as 10°F or -12°C!
BROCCOLI RABE: Though in the brassica family, broccoli rabe (or rapini) is actually a "cousin" of broccoli. Its florets are much smaller, its stems more slender, and its leaves more plentiful. Unlike broccoli, however, all parts of broccoli rabe are edible — its stalks don't require peeling because they're not as thick and tough as broccoli's. Rapini is known for its bitter taste, and is particularly associated with Mediterranean cuisine. This was one of a ALL-TIME FAVORITE VEGETABLES when I lived in Italy! It's amazing roasted with garlic, salt and olive oil!

POPULAR VARIETIES FOR SW MICHIGAN

CALABRESE: As mentioned above, Calabrese is an heirloom variety from Italy. It produces heads about five inches across, is fairly easy to grow and is super versatile in the kitchen. It can be grown as an early spring crop or a fall crops, but I'll tell you in a minute why I DON'T RECOMMEND growing it as a spring crop! Best news? It can be ready to harvest within 60 to 90 days of planting!
GREEN GOLIATH: Green Goliath is a hybrid variety that is tolerant of both heat and cold, which is great for Michigan springs! It produces heads up to 12 inches in width and is known for its ability to produce multiple side shoots after the main head is harvested, extending the harvest period. So, you can basically harvest from this variety for about three weeks versus one! Keep this variety in mind as it is less likely to bolt as the weather warms up (broccoli is prone to bolting/flowering in Michigan's short springs). AND its flavor gets SWEETER with light frosts, tolerating temps down in the 30s without cover. Once temperatures dip, however, cover with mulch and a frost cover to extend its growth into winter. Lastly, GG is ready to harvest in 55-58 days! So you can grow this variety multiple times throughout the year!
WALTHAM 29: This variety is known for its cold-hardiness and impeccable flavor! Its seed are open-pollenated and produce medium-sized, blue-green heads with a mild flavor. The disadvantage, however, is that Waltham 29 is quick to bolt, so you don't want to grow it in a SW Michigan spring. This variety is best started indoors in July and planted out in August when the weather is cooling. You can also direct sow seeds 2-3 weeks before your first frost date, and it will be ready in 50-60 days after transplanting! If possible, though, I recommend starting seeds indoors for better germination.
DICICCO: DiCicco is another tasty, Italian heirloom variety also known as Italian Sprouting or Tuscany Kale. It's also thought to first be cultivated by the Romans. It is small to medium in size with tight clusters of large green florets on a meaty stem. You can expect to harvest 2 to 3 main heads from each plant. DiCicco matures in 60 to 80 days, so start them indoors 6 to 8 weeks before you plan to plant.
PURPLE SPROUTING: An eye-catching variety, Purple Sprouting Broccoli produces numerous small, purple-tinged florets on multiple stems. It has a slightly sweeter taste compared to other varieties and adds a pop of color to the garden and the dinner plate. In Michigan, you can overwinter this variety in a hoop house or greenhouse and it will be ready with florets in the early spring! This is variety takes 180 days to mature, but is worth the wait!
ROMANESCO: Another Italian heirloom and a cousin to cauliflower, Romanesco is a super unique variety of broccoli known for its striking, light green, spiraled head. It has a delicate, nutty flavor and a firmer texture compared to traditional broccoli varieties. When full grown, it can span two feet in diameter and is a heavy feeder, so give it plenty of space and prepare the ground with nutrients. It is also prone to bolting in heat, so plant this variety after the heat of the summer, starting seeds indoors about six to eight weeks beforehand and it will be ready in 65-95 days from seed.

When to Start Broccoli Seeds in Michigan

I've learned over the past few years that broccoli can be a bit finicky to grow, especially with Michigan's short spring season. The abrupt shift from cold/cool spring weather to warm/hot summer weather causes plants like broccoli to bolt before they've even had a chance to mature.

Actually, several varieties of broccoli grow fine in warm, even hot weather, but it's the shift from cold to hot that tells the plant it's time to go to seed. So, you have to plan carefully to avoid planting broccoli too early in the season.

In fact, for the most part, I don't even recommend planting broccoli out in the spring. You're just setting yourself up for disappointment.

As I mentioned earlier, understanding the needs and growth habits of each variety will help you plan when to start your seeds and when to transplant them to the garden.

Some broccoli varieties do well in heat while others bolt at the very presence of warmth. Some are short season varieties and others need a LONG time to mature. So, where do you start??

I like to think in terms of early, mid- and late season harvests. In other words, I want an early harvest, a mid-season harvest, a late season harvest, and with broccoli (and most brassicas) a fall or even winter harvest.

EARLY SEASON - Waltham 29 is your best bet here! It's a cold-hardy variety that is ready in 50-60 days after transplant! That's pretty amazing!

Start your seeds indoors about 6-7 weeks before your last frost date. In SW Michigan, that's generally the end of March/beginning of April but ALWAYS check your "frost date" calendar for whatever year you're in, because frost dates change from year-to-year!
Harden seedlings off when they're about 6" tall. This is generally around week three. DON'T MISS THIS STEP! You could lose your plants if you don't acclimate them to the cooler weather outside (read more HERE & HERE).
Transplant seedlings about 3 weeks before your last frost date. If they've been hardened off, they won't mind the cooler days and should tolerate light frosts. You can always cover them with a sheet or frost cloth if you have an extremely cold night; but again, Waltham 29 is a cold-hardy plant.
Harvest broccoli by the first week of June!

MID-SEASON - Green Goliath is a go-to mid-season crop, as it is both cold and heat tolerant. It's ready to harvest 55 to 58 days after sowing, so you can start these plants a few weeks after your early season broccoli. AND if you want another harvest after that, you could start some again a few weeks later.

Start your seeds indoors about 3 weeks after starting your early season broccoli (late April).
Harden seedlings off when they're about 6" tall.
Transplant seedlings into garden about 5 to 7 days after hardening off.
Harvest about two months after starting your seeds, which will be around late June or early July, depending on when you started them. Remember you can succession sow another round of seeds in May if you want another harvest in mid- to late July!

LATE SEASON/FALL - In July and/or August, sow Calabrese, Romanesco, DiCicco, Waltham 29, or Purple Sprouting broccoli for late summer, fall, winter and even early spring harvests. The process is basically the same, just pay attention to the maturity dates of each variety and when you want to harvest them, and then you'll know when to start your seeds.

A NOTE ON MATURITY DATE RANGE: If you're wondering why each variety has a range of dates for when they'll be ready to harvest, there are multiple factors involved. Seed companies can only control for the quality and variety of seed they produce. They cannot control for HOW those seeds are grown.

Germination usually takes 7-14 days, depending on your propagation methods. Are you sowing them directly in the ground? Is the ground cool? Warm? Are you sowing them indoors? What's the temperature indoors? Are they on a heat mat? A cool window sill? All these things matter and can either speed up or slow down your germination! So, the maturity dates on your seed packets have to account for this uncertainty. WANT TO SPEED UP GERMINATION?? Watch this video below 👇🏻👇🏻

Outdoor Conditions can also vary. Where is the broccoli being grown? Somewhere hot with a long growing season? Somewhere cooler with a short growing season? Is there adequate nutrients in the soil? Moisture? Sun? Can you see all the variables that might affect how long it takes the broccoli head to develop?
Side Shoots: I haven't found anywhere that states this for certain, but I believe some of the more expansive date ranges account for the side shoot production that occurs after you harvest the initial brocolli head. As stated above, there are multiple varieties that are known for their abundant side shoots.

Regardless, just be mindful of the maturity date range and make sure it fits into your planting calendar. The nice thing about broccoli is that you don't have to worry about harvesting it before your FIRST frost date. In fact, you can grow and harvest broccoli well after it, especially your cold hardy varieties like Waltham 29 and Purple Sprouting.

Germination & Seedlings

** The information in this section is specific to broccoli seeds, for more in-depth information, suggestions, and recommendations for best seed-starting practices, be sure and check out my Seed Starting 101 Workshop or Guidebook! **

CELL TYPE: I suggest starting broccoli seed in larger cells (2" x 2" or larger) versus smaller plugs (1" x 1" or 1" x 2"). You CAN grow them in smaller cells, but be prepared to prick the small seedlings out and transplant them to a larger cell (or outside, if the temperatures are suitable) around week three. If you don't, your seedlings will be much smaller and less healthy due to lack of space and nutrients.

SOIL MEDIUM: The seed itself will provide the seedling everything it needs (nutrient-wise) until it grows its first set of true leaves (the first set of leaves that emerge are the cotyledon leaves; the 2nd set of leaves are the true leaves). Once the true leaves emerge, the young seedling will need to get its nutrients from the soil medium it's planted in, which is why I recommend starting your seeds in a good, organic compost or potting soil versus seed starter or coco coir.

GERMINATION: I highly recommend you start everything indoors under grow lights and on a heat mat. This provides the seeds the BEST environment for germination, which speeds up your timeline and gives you the biggest bang for your buck (in other words, more seeds will germinate!) Again, watch the video above for more on this topic.

TEMPERATURE: Once the seeds have germinated, you can (and should) move the tray off the heat mat onto another shelf with grow lights. Heat isn't important at this stage, as broccoli generally likes cooler temperatures. If you have an outdoor greenhouse, growing broccoli seedlings there would likely be ideal, depending on which variety you're growing. Growing in a basement space is great as well, as the temperatures are typically lower than the rest of the house. All of this being said, I have successfully grown my broccoli on my grow shelves in the main hallway of our house with temperatures around 60-65°F.

WATER: There's a lot of debate about how to water seedlings. Water from the top? Water from the bottom? Which is better? I honestly do both and have great success! Do what works best for you and your growing situation. MAKE SURE the soil is always moist (not drenched) during germination, however, as the seeds require moisture to germinate!

My top watering tips are to avoid under watering and overwatering by keeping close watch on your seedlings trays. Use TOUCH (damp soil or crumbly soil), SIGHT (looking for water in trays & soil moisture), and WEIGHT (tray heaviness indicates soil saturation) as indicators of water needs. When my drainage trays are bone dry, that's usually my best indicator I need to water, as well as droopy plants (but you don't want to get to that point.)

Moving Seedlings Outdoors

While we may be used to the idea of hardening off our warm- and hot-season plants, cool season plants like broccoli to be hardened off as well, especially if they've been growing in a nice, cozy temperate environment such as your house.

For more information on HARDENING OFF YOUR SEEDLINGS, check out THIS POST, and THIS POST.

In general, you can use this suggestion as a guide for WHEN to move your plants outdoors:

Weeks to grow transplants indoors: 3 to 4 weeks
Start seeds: March to April for a spring crop; June for a fall crop
Plant out seedlings: April to May (spring crop); July to August (fall crop)

Broccoli plants need a lot of room to grow adequately. When it comes to garden space, the more room a broccoli plant has, the faster it will grow and the larger the head will be! Additionally, If plants are too close, they will bolt, making the plant inedible for it even matures.

When spacing your garden beds, remember that broccoli plants need enough room for their crowns and leaves to grow very large and expand. So, if you're growing in a raised garden bed, plant seedlings close to the outer edge to allow their leaves to extend outside the bed. This will also free up space in the middle of the bed for additional plants.

If you’re growing broccoli in rows, consider planting your seedlings in a zig-zag pattern as opposed to in a straight line. Broccoli plants grown in a zig-zag pattern are less likely to crowd each other out. They will produce larger yields too. Also, place seedlings on the edge of the row to maximize space.

Caring for Broccoli

Broccoli, like most brassicas, are heavy feeders and require consistent moisture for faster growth. I like to add a thin layer of blood meal or compost to the bed before I plant in my seedlings, unless I've prepared the beds with plenty of compost or chicken manure the previous season.

Doing a soil test will be helpful to know the condition of your soil and what amendments may be necessary to add. You can purchase a kit online or talk to your local extension representative about conducting a free soil test. Most extension offices offer this service as well as local nurseries. So, ask around. But in general, broccoli prefers soils nitrogen-rich soil with a ph of 6.0 to 7.0 that drains well yet retains water.

Stick your finger a good inch or two down into the soil to check moisture levels. If it feels dry, water. If it feels moist, don't water. Along with that, a really good, long water one- to two times a week is better than shallow waterings throughout the week.

Watering deep encourages deeper root growth, which therefore creates healthier, more stable plants and bigger heads. I use a heavy, duty 6-foot sprinkler that I run for one hour per garden once a week. This is generally enough water, unless it's a super hot week. Obviously, rain water is best, so adjust your watering schedule if you've gotten plenty of rain that week.

When to Harvest Broccoli

Harvest broccoli in the morning, when the buds of the head are firm and tight, just before the heads flower. If you do see yellow petals, harvest immediately, as the quality will decrease rapidly.

Cut heads from the plant using a sharp knife or garden sheers, taking at least 6 inches of stem. Make a slanted cut on the stalk to allow water to slide away. (Water can pool and rot the center of a flat-cut stalk, ruining the secondary heads.)

DON'T pull up the plant from the roots, as most varieties have side-shoots that will continue to develop after the main head is harvested. You can harvest from one plant for many weeks, in some cases, from spring to fall, if your summer isn’t too hot.

Immediately store your broccoli in the fridge to prevent the head from drying or opening. If you wash the head, make sure it's thoroughly dried to prevent mold and mildew. You can also flash freeze small pieces of broccoli and then add to freezer bags to have broccoli available throughout the year.