Broccoli is Hard to Grow

At least for me, onthe roof. 

The Problem with brocolli, is that it is a cool season crop, but it takes a fairly long time to mature.   Last year I put my transplants into their raised beds in early to mid April.   The seemed to grow fast, big, and hardy.  But by late June or early July when they began to develop their heads, the temperature of the soil was often above 80 degrees.  I tried to cool things down with shade-cloth, but the ambient temperature of the roof (it was a hot June, too) overwhelmed any coolness the soil might have retained.  On the roof, the soil will be the same temperature as the air, or warmer, as the roof  surface can go well into the 100’s–hot enough to burn skin.

I am devoted to brocolli.  When my wife and I used to get our veggies primarily from the grocery store, we ate brocolli almost every night.  One way or another, I determined, I would grow good roof-top brocolli.   So I started my seeds inside in mid-January, and planted good sized seedlings in the middle of February.  This brocolli would not suffer from over-heating. 

About two weeks ago the first  tight heads began to form and grew steadily larger and fuller.  But about a week ago something else happened.  Instead of growing large and tight, the earliest ones began to open and spread.  They was about to flower, even though the soil temperature dips into the 50s at night, rising to the 70’s, only, during the day.  Perfect brocolli growing temperatures.  What happened?

Apparently prolonged exposure to cold weather can cause brocolli to flower prematurely, to create “buttons.”  While still tasty, unlike the heat-caused bolting, these were paltry looking little sprouts–the brassilica version of Charlie Brown’s Christmast  tree.  I included them in the CSA boxes this week.  I hope my subscribers  remember the experimental nature of my project as they nibble on these gangly little guys.

The good news is there is another round of brocolli, about 2 or 3 weeks behind this one, just starting to form its heads.  They look tight.  They didn’t suffer the cold nights of February.  Perhaps they will grow large and tight.


4 Responses to “Broccoli is Hard to Grow”

  1. Birchnose Says:

    Great blog, I’d love to see more photos if possible!

  2. Heidi Says:

    I do not garden, I frequent the farmer’s market, so I have no clue….but I am wondering, how would Romanesco do as compared to broccoli? Have you eaten it? I like it much more than broccoli, and it’s mathematic.

    (In case you’re wondering, I think I found you via treehugger or some such place. I am so looking forward to pictures!)

  3. rooffarmer Says:

    Hello Heidi,

    I don’t know if I’ve had Romanesco. Is it the same thing as Broccoli Raab? I grew some of it this year but it didn’t do all that well, and unfortunately took up a lot of space for how much it produced (one of my major concerns is amount of produce per square foot). I’m intrigued by the description of “mathematic.” Say more.


  4. Bruce F Says:

    Hi Erik,

    Jay Sand from Philadelphia sent me an email mentioning your site – fantastic project you’ve got going on.

    I read a few of your earlier posts and feel like we’re headed in the same direction. Nice to know about other people growing vegetables on their rooftops.

    I had the same problem with spindly broccoli heads this year, at least on the ‘Green Goliath’. My ‘Romanesco’ takes a bit longer to set up so there’s still hope for it.

    Check out this link on Romanesco –

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