It could be that the region you’re in isn’t designed for those veggies

I had this happen to me with lettuce in FNQ. I guess some vegetables are better than others to plant.

Here for the answers…. this always happens to me

As a beginner Gardner I would really love to know this to!

I had terrible time with broccoli and cauliflower this year. But I couldn’t figure out why

Hey I’m not sure where you actually live but the number 1 reason most veggies, especially cauliflower and broccoli flower and goto seed “ bolt” is stress. Most of the time it’s due to the temperature in the ground. They don’t like being hot, to keep them cool you can try adding a really thick layer of mulch over the soil around your veggies, and make sure they get plenty of water in the mornings before the sun can get to them! If they waste all their energy on simply surviving you won’t get a good harvest and it’s the plants natural response to “reproduce “ before it dies off, hence the flowers and seeding

Some seasons are worse than others. This year seems to be a bad one. It’s frustrating after all the effort.

You need to pick broccoli regularly to stop it going to seed, where you cut it, it will regrow. Plant early autumn while there’s enough heat to get it started but not too much to make It go to seed. Feed and water well. Inconsistent watering can cause plants to bolt, as can excessive heat. Timing is everything with vegies and every location is different

I put a lot of prep into garden beds before planting.

I don’t have any advice sorry but am thankful you asked this question because I have learnt a lot from the comments.

Really depends on timing, environment and soil and trial and error. Ensuring your planting in the correct seasons for growth is a must, I have started putting sugar cane mulch around my vegetable and that has dramatically helped. Ensuring you have enough water for moisture. I have sandy soil and I struggle to grow brown onions but everything else seems to grow great. The first year I messed up my pumpkin and Carrots simply by having them in too shady conditions and not enough water. Since moving them to a different area they have flourished

Maybe get some advice from a garden centre and even describe the soil type. I get lots of advice from our local garden centre.

From one season to the next I find success changes. Weather these days is insane and unpredictable. TBH I have found a facebook group for my state where people are very passionate and knowledgeable regarding growing fruit and veg, plus they are in my region thereabouts so weather considerations are applicable. Plus it’s your own trial and error with soil prep (so so important), mulch, watering schedule, type of plant etc. So many variables but I feel like while failure is disappointing, the learning and trying is knowledge for next time! Keep going!

I was hoping to find some helpful answers here, but nope. My broccoli, cauliflower, cabbage and brussel sprouts all did this. I put it down to lack of sunlight as I tried to grow them through winter in Tassie.

Really depends on the environment but I find mulch works for me

Sorry to see nobody answered your question yet !
You might find some explanation and tips in this article
https://gardendrum.com/2015/05/14/how-to-stop-veggies-and-herbs-bolting-to-seed/