Indigenous weeds are germinating and generally making a nuisance of themselves in your garden. These are seeds that were blown around by the wind or distributed by animals during the hot dry summer months. This can be especially problematic in lawns and should be attended to before the weeds themselves start producing seeds which simply exacerbates the problem. Once you allow weeds to establish themselves in your garden and they go to seed, you are inviting a whole raft of problems which can be rather expensive to rectify. This is why I recommend that every garden has a plan in place where regular upkeep takes place.
Another suggestion to avoid weeds, is to lay down bark mulch which helps in feeding the acid loving plants and keeping the water in the soil. This also seems to totally control the spread of weeds. Yes there are still a few stragglers that get through the mulch, but it combats the weed growth
Most chemicals are available from hardware stores and nurseries to help you eradicate weeds, but if your own attempts fail to deliver results, it may be a good idea to get a professional company like Cape of Storms in to help you.