Well, you could've been me -- I sowed my Brussels Sprout seeds a little late last spring. I don't feel like looking it up now, but I remember it was needing to sow mid-late May to be planted out by Mid-June. Well, that seemed absurd, considering I was still struggling with getting my warm-weather transplants in the ground. So I sowed the seeds some time in Mid-June, along with my other fall cole crops.
I discovered that it was REALLY difficult to grow fall cole crops when the Cabbage butterflies and Diamond Back moths were in full regalia, especially when the cole crops were interplanted with taller growing and fruiting summer vegs, preventing me from covering them up. After fighting that losing battle, the 2 remaining Brussels grew to about 12", then stalled, then we had fall and winter. I figured them a goner for sue. The flimsy hoop cover I put over them collapsed under 24~30" of extra-ordinary snowfall we had over the winter, presumably crushing the Brussels.
This spring, to my surprise, the two emerged unscathed. They hardly grew, however, then went onto produce no bigger than marble-sized sprouts that promptly unfurled and shot off into flowers in the unseasonable 90Ã‚Âº heat wave we had in early April. I couldn't even harvest the seeds because these were F1 Diablos.
I did, however, harvest the flower shoots and turned them into a stirfry.
So am I sowing my Brussels now? I'm looking at the calendar thinking I really should. But the truth is I started those seeds along with the rest of my coles (3 kinds of cabbages and a cauliflower) They are already planted along with the others, and the battle with the White Cabbage butterfly cats have already begun. I picked off two of them today.
My earliest cabbage is starting to head up now, though the red cabbage still looks like a well-grown transplant. I expect hot (peppers and eggplant planting) weather to hit by the end of this week or next week at the latest So we'll see what the Brussels decide to do. If they stall now, then they're in good growth for fall finishing -- I hope.
And maybe I can hit that "harvest after one or two light frosts" window.
It might all be a question of finding the right variety and the correct planting schedule for your particular area. What I'm doing this year is NOT what the instructions I've read anywhere say to do.