[Grubbypaws]

This is my first year growing PSB. The main heads are beginning to form and I am wondering if I should feed them and if so with what. Doing a quick google search the recommendation is to feed them with a liquid feed. Would tomato food be OK?

[mumofstig]

I don't think it's worth feeding them with anything, 'til it warms up a bit.

Then I use Wilko's liquid veg food only a couple of £s a bottle, green veg need less Potash than tomatoes.
Alternatively put some chicken manure pellets around the roots, if it is dry, water it in well.

[Goosegirl]

I agree with MOS because they won't grow any bigger at this time of year even if you gave them elephant poo.

[Hobovore]

How  fortuitous, I was going to make a purple broccoli thread and there is one right here to add too!

I planted mine last year, they grew and then got mangled by caterpillars. They recovered beautifully and so far have overwintered but are now being mangled by pigeons.

As these plants are now almost 12 months old...when do they start producing?

[mumofstig]

Depends on variety and the weather , so the answer is when they feel like it 

[Dev]

If you start them off too early they make very large plants, which makes it difficult to net them. Start them in June and you get smaller plants but plenty of spears. If you have pigeon problems (and most of us have) you should net them. I use debris netting which is pretty good for keeping butterflies off as well (until they discover the holes!).