You don't say whether they're 'heading' or sprouting 'brocolli's'... but, both are treated about the same during growing... the most likely is heading, which forms a central 'head', which, when harvested will produce other 'heads' along the stalk.
Watch for curling leaves which is the first sign of aphids... they will be seen on the underside of the leaves and can easily be treated by mixing about a teaspoonful of common dish soap ( think ya'll call it 'washing up' soap, no? [I'm in the U.S.])... regardless, mix thie soap in a spray bottle with about a quart of warm water and thoroughly soak the leaves... especially the undersides.
When you water the plants (if you need to) avoid getting water on the heads... wather thoroughly but don't make them stand in water.
Harvest before the heads begin to turn yellow, since the heads are made up of flower buds, whcih when opening will turn yellow.
They are pretty hardy but don't like overly warm weather... if it turns really warm with sunny days, you may wish to shade them with a fine netting for at least part of the day...
Good luck!