Why Broccoli Didn’t Flower

Recently, a gardener asked our Master Gardener clinic why their broccoli didn’t flower. That question comes up regularly, and I’ve studied it in my own garden, with my own successes and failures.

Someone also asked me the other day if it was too late to plant winter brassicas.

Finally, I want to share a tip about what to do with your Brussels sprouts plants this time of year.

So I’ll tackle three brassica topics in this post. Here we go.

Why broccoli didn’t flower

If your spring- or summer-planted broccoli didn’t set its flower buds (the part we eat), it could be due to  planting at the wrong time, uneven watering, fertilization issues, planting bad starts or bad treatment of seeds or seedlings.

For summer harvest broccoli, timing is tricky, because you want to plant earlier in spring so you get the crop before the summer heat, but if you plant too early, the broccoli won’t get a robust start. If you plant too late, the heat stresses it. I’ve had best success when planting starts in early to mid-May (or doing a succession of plantings through May). That means you’ll be cutting heads in mid-July and into August.

In my experience, they like a lot of compost, which also helps to regulate moisture. So I put them in a well-composted bed, and add a top-dressing a few weeks after planting. I’ll feed once with a balanced complete organic fertilizer, about a month after planting.

Fertilizing with a lot of nitrogen as they’re trying to form heads could prevent the plant from flowering, and probably just produce more leaves.

For overwintering broccoli like purple sprouting (my favorite), I start the seeds in late May/early June, then plant them out in August. Also tricky to keep them consistently watered during that seedling stage. I top-dress with compost in mid-September, then lay a bed of straw mulch over the soil for the winter. They’ll send up a small central head by early March, followed by sprouts.

I don’t grow fall-harvest broccoli often, but I believe that it’s on the same planting and transplanting schedule as sprouting broccoli, but will produce heads in late September. I found the harvest to be small, so now I just concentrate on the sprouting ones.

Brussels sprouts ‘tip’

On to the Brussels sprouts. If you have winter harvest sprouts in the garden now, you’ve probably noticed small sprouts forming along the leaf axils. Also, you’ll probably see a denser set of leaves forming like at the top of the plant. If you cut off that growing tip, the sprouts should develop faster and more robustly. That’s because the plant is now putting all its energy into the sprouts rather than the new leaves.

Here are photos showing this cut on one of my plants:

Brussels sprout topBrussels sprout top cut

Planting brassicas now?

One final note about whether you could be planting brassicas now. The answer is, not really.Most brassicas should be planted in May and June, and transplanted in August, or at the latest in early September.

However! If you can find healthy kale plants still in the nurseries, you could put them in, but I would not expect much production from them over the fall and winter.

Who’s Got Next in 3 Open Beds?

I took inventory last weekend and found three spaces in my vegetable garden that are ready for the next crop rotation. Right now, at this crucial time for getting the fall and winter garden going, I have at least that many choices of crops to start.

Lettuce in flower

We had many salads off this lettuce bed, but now it’s regrown and gone to seed. I’ve enjoyed the stately flower stalks, but now it’s time to rotate fall peas into this space.

Space #1: The Garlic Bed

The garlic came out in early July, so this bed has been sitting “fallow” for a few weeks.

Location: The garlic filled the west end of a large bed. It gets good summer sun, but is fairly close to a tree and some bushes, so the lower angle of the winter sun causes part shade.

Strategy: I’ll plant some root crops in succession, starting with beets. It’s a big bed, but I will only plant one short row each for the next few weeks, using different varieties with 50-65 days to maturity. In September, I’ll fill the rest of the bed with carrots for overwintering. The shorter-season beets will be ready by late September, but the longer-season ones will hold in the bed well into winter (with a bit of mulch), getting sweeter with the fall frosts.

Bed prep: Last week I dug a light dusting of complete organic fertilizer into the soil, and covered the bed with a welded-wire mesh so the open soil doesn’t become a cat’s litterbox. Before I plant, I’ll spread an inch of compost on the soil and dig it in.

Since both of these crops are susceptible to flying insect pests laying their eggs on the plants (carrot rust fly and spinach leafminer) , I will cover the entire bed with a floating row cover (FRC). To make it easy to tend and harvest, I’ll set up cloche hoops and stretch the FRC over that. If we get unusually early frosts, I can switch to plastic to protect the plants for winter.


Space #2: The Pea Bed

We had a great year for peas, with a harvest longer than normal. The vines just got pulled last week. Annual flowers and some spreading thyme crept in around the pea trellis.

Location: This is a very visible bed right by the main path to my deck.

Strategy: I want Brussels sprouts here. Sprouts are a long-season crop that will not mature until December or January, and I like to have them in a visible spot so I can watch the sprouts develop.

A few weeks ago, I started Brussels sprouts from seed, and the plants are quite small, with just two sets of leaves. I’ll hold them in the pots for another week and then plant them.

When it comes time to plant, I will hedge my bet  by going to the nursery and buying some starts, and will interplant them with the ones I started from seed. That will give me a second variety too.

Bed prep: I’ll pull up the annual flowers (now gone to seed) and dig out the thyme. Since neither the flowers nor the peas are “heavy feeders,” soil fertility in this bed should be fine, so I don’t need to fertilize. But, since brassicas like a rich soil with good water retention, I’ll dig in some compost, which will also boost fertility a bit. I’ll also use FRC over the young plants to ward off the cabbage moth.


Space #3: The Salad Bed

This spring I sowed a mixed bed of lettuces and other greens, which produced well and gave us salad from April to mid-June. We enjoyed the buds and flowers of the arugula and mustard greens, but those plants bolted first. Then the lettuce turned bitter, and now the plants have shot up and are going to seed. Since lettuce produces a beautiful large seed head, I’ve been letting them stand in the bed.

Location: This is part of a raised bed off the lawn. The trees have grown up in this area, and with the position of the summer sun, the bed now gets shade about half the day. It gets good winter sun after the deciduous trees have lost their leaves.

Strategy: The part shade should be great for a crop of fall peas. These can be planted through July, so I’ll get them in the ground soon.

Bed prep: To prevent the curious, omnipresent crows from yanking the seedlings out of the ground, I will put a layer of floating row cover over the bed. This should prevent slug attacks too, and will keep the seedbed moist during germination, a key to successful summer planting.


Who’s got next?

Well, that’s the plan for three beds and four crops. But there are so many more choices coming: fall salad greens, overwintering kale and sprouting broccoli, Asian winter greens, collards, turnips, kohlrabi, fava beans, cover crops…a long list.

But almost as long is the list of beds that will be free soon: carrot bed, potato bed, onion bed, last-of-the-kale bed, buckwheat cover crop bed, and the quinoa and orach bed. Later, more space will come with the harvest of rutabagas, squash, peppers and tomatoes.

During the height of summer, fall and winter are on my mind. And as I pull out mature crops now, I’m getting more than a summer dinner. I’m getting valuable real estate for the next rotation.


What to Plant Now for Winter Harvest

It may seem crazy, but just as your cherry tomatoes are forming, it’s time to think about winter. seedlngs un traysBut consider the stars of our winter garden: long-season broccoli, cabbage and Brussel’s sprouts. In order to get the sprouts bulging, the cabbage head firming up and the broccoli sending out its shoots, you need to grow a plant that is fairly mature before the onset of winter.  That means starting soon.

The main challenge to winter gardening in the height of summer is water. These cool-season stars need to be grown through our warmest months, and they still might be seedlings when a hot spell hits. So, a cool-season gardener must keep the warm-season vacations short.

Here are a few techniques to make this challenge a bit easier to bear:

Start in flats. Rather than sowing directly into the garden bed, sow into pots and plan to transplant. That way you can keep a closer eye on the moisture content of the soil while the seeds are sprouting — a crucial moment.

Another bonus: the plants will be mobile. You can move them to the shade if you need to be gone for an extended period during a sunny period. Better yet, if you’re planning a weekend away, deliver the tray to a neighbor who can keep an eye on them for you.

Plants you start in pots now would be ready for transplanting near the end of July.

Cover them for shade. Floating row cover, the thin, spun-bonded fabric that lets light and water through, serves in summer as an excellent shade cloth. Drape it lightly over the plants and hold down the edges with earth staples or stones as weights.

An extra benefit of this technique is that the FRC will prevent pests from messing with your plants. The cabbage moth cannot land on leaves that have been covered, so it won’t be laying its eggs, which hatch into voracious larvae.

One caution, though: don’t expect the material to solve all your woes. Slugs and snails will still be looking for your tender seedlings, so patrol the area regularly until the plants are big enough to withstand such an assault. FRC will help the soil retain moisture, too, but again, don’t expect it to do all the work. Check regularly under the fabric to see that the plants are staying well-watered.

Use plenty of compost for moisture retention and a bit of fertilization. Digging in some compost before planting will improve the tilth of the soil, and top-dressing with it after the plants have put on some good leaf growth will provide an additional layer of moisture-holding capacity.

Be aware, though, that top-dressing (spreading a modest layer of material on the surface of the soil around the plant) can get crusty in summer application, which would cause water to run off rather than soak in. Cultivate it lightly before watering if it seems to be crusting over; this will allow the water to get through.

Other things to plant now: parsnips, carrots, beets, chard, kohlrabi, collards…an amazing array of choices for fall and winter eating.

Soon it will be time to start a second or third planting of short-season crops, like lettuce and peas,  for fall harvest. But for now, as you pinch tomato suckers and anticipate the first blush from a chorus line of cheery cherries, think a bit further ahead, to the tasty cool-season crops you’ll want to put on your holiday dinner table.

Brussels Sprouts…Sprouting Buds

The last of the Brussels sprouts have finally come out of the garden, and they held pretty well until the intermittent warm days we’ve had in the last couple of weeks. Then they started to really, well, sprout. The remaining loose sprouts are shooting up into mini flower stems.

Here’s the last good stalk, showing its interesting spring habit.

Brussels sprouts sprouting

I cut away the leaves along the sprouts, but left this one eruption for show-and-tell. If it sat in the garden much longer, all of the

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sprouts would look like this. In fact, here’s another plant that didn’t sprout-up properly, so I’m just letting it go to flower.
Brussels sprouting to flower

The main stalk of the plant bends left, and toward the bottom, a number of sprouts have opened up and shot out at a right angle. A few of the flower buds are about to open.

I could still be eating it at this stage. We often eat the Brussels sprouts leaves if the plant doesn’t produce sprouts but just gets very vegetative. They’re a quicker stir-fry and still have that tangy, smoky flavor unique to this cool-season crucifer, Brassica oleracea, Gemmifera group. You can also eat the flowers, which provide a light sprout flavor when tossed into the dish briefly at the end of cooking.

I’m often asked about planting Brussels sprouts, as it seems that many times they do not properly produce sprouts. I’ve certainly had my share of failures (see above). I think it’s a combination of timing, soil fertility and weather. Well, isn’t everything?


Open-pollinated (OP) Brussels sprouts range 120 to more than 200 days to harvest (from transplanting). That’s 4 to 6 months, plus a month if you grow them from seed, so you really need to plan ahead. There are F1 hybrids that have been bred to mature much faster, as quickly as 75 days or so. I like to grow the OP varieties and harvest in winter, because I like the way brassicas get sweeter after they’re hit by frost.

For such long-season plants, I always start them in flats and then plant them out into the garden. I’ve found that if I get the transplants into the ground by mid-June, I should have sprouts for the holiday feasts. If I don’t get them in until mid- to end of July, I’ll be eating them in February and March, and they may “bloom.”

It’s a good idea to grow two varieties with different maturity dates, or practice succession sowing, so you will have a longer harvest. (The F1 hybrids are also planted in May and June, for harvest in late summer.)

The seedlings will need 5-6 weeks to transplanting, so that means doing the first sowing in pots by May 1.


I usually apply one feeding of liquid organic fertilizer to my starts, when they’ve gotten a few sets of leaves and are maybe 2-3 inches tall. When I plant them in the garden, I work in a spadeful of worm bin compost or a dusting of complete organic fertilizer (COF). Along with the N-P-K, they need the secondary nutrient sulfur and the trace mineral boron, both of which are present in organic fertilizer.

I do not fertilize much once the plants are in the ground. I am betting that, once the plants are established, the active soil food web will take over and deliver enough fertility throughout the root zone of my plants.

For overwintering plants like Brussels sprouts, they need to put on most of their growth by mid-fall, say by October 1, because the cooler soil and shorter days trigger much lower activity in the soil food web, and fertilizers will not be as available or taken up by the plants.

My final step in proper plant feeding is to get a soil test done every 2-3 years to see how I’m doing. If you’re growing crops in your vegetable beds year-round, you need to pay much more attention to soil fertility.

My favorite OP varieties: Roodnerf, Long Island Impoved and Rubine. Get them from Territorial Seed Co., Baker Creek Heirloom Seeds or Seed Savers Exchange.

And if you’re growing organically (and I hope you are), you also need to pay attention to potential diseases. Fungal problems like club root and bacterial diseases like black rot can affect brassicas, and the best defense is good garden sanitation and crop rotation.


The transplanted Brussels sprouts will be still young plants, just starting to get some size, by the time our warmest summer weather hits in August, so you might be tempted to plant them in partial shade. I advise against that. I’ve had best production from the plants in the most sunny spots. The challenge is keeping them well-watered during their crucial late-summer growing season.

They will benefit from a bed with lots of compost, and a top-dressing of mulch on the soil during that warmest time. That will help the soil retain water better, which means less stress on the plants. (Another stressor at that time of year is aphids, which love to swarm along the juicy stem and thick leaves. Douse the plants from overhead with a hard spray of water whenever you see aphids to keep them at bay.)

Fall and winter treatment

In the fall, a predictable cooling weather pattern provides the best situation for overwintering plants.

I apply a loose mulch of straw around the base of the plants in October, to keep the soil slightly warmer and prevent the roots from becoming exposed and desiccated by winter winds. If an unpredictable early freeze is forecast, I might throw a blanket of floating row cover over my brassicas to protect them a bit more.

Brussels sprouts nutrition

But by December, the plants should have acclimated to winter, and don’t need covering. In fact, covering can be detrimental, as it could provide a cozy spot for pests like slugs and snails to take up residence.

Once the plants have reached “full frame,” you can nip off the tip of the plant, so it will send more energy into sprout production. I often forget to do this, and still get sprouts. Often, too, my sprouts are smaller than the grocery-store ones, but sometimes sweeter. To harvest, twist each sprout off the plant, working from the ground up, or just cut off the entire stalk if you need a lot.

It’s a long haul to grow a vegetable like this, but these tasty bite-size cabbages are worth the effort, packing a couple of hearty meals on each plant. This year, why not give them another try?

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