Further to my post about weeding I have attached some photos of the out of control flowers in question. This is a quarter acre lot. The flower beds are around the entire perimeter in the side and back of the property and there is a good size garden area in front of the house. Depending on where they are the garden bed runs anywhere from 4 to 15 feet wide. They're hardy little suckers. My husband dumped a load of gravel on the side garden that he plans to turn into a driveway and they're coming out through a foot of gravel. I thought they might be called lupis? The other ones I don't know what they are. They're a blue/purple color and can be a couple of feet high and they are everywhere in the side and back perimeter of the property. We plan to rototill everything because its so much out of control. Will rototilling stop them? Putting down black polyethelene for a year didn't do the trick. And yes in the last photo that's a poor rhododendron trying to live amongst the weeds. Nasty blue weeds everywhere ( photo / image / picture from whistler's Garden ) Close up of the weed I can't kill ( photo / image / picture from whistler's Garden ) Close up of another plant that grows like weeds ( photo / image / picture from whistler's Garden ) Portion of the back yard taken over by weeds. ( photo / image / picture from whistler's Garden )
The first ones are some kind of muscari - grape hyacinth, grows perenially from a bulb so it could be harder to get rid of. The third pic is of a Centaurea, which is a self-seeding perennial and can quickly take over a bed. If you really need to get rid of them (keep in mind that some people pay good money for these plants at nurseries!) you could dig them up - the muscari bulbs should only be a couple inches deep - or else drench them a few times with vinegar.
The first two pictures are of Hyacinthus orientalis var. albulus. In the Pacific Northwest they are a bulb that does multiple, but are enjoyed by me. They will naturalize as they seem to have done in your yard. You can move them about any time to a more desirable location. Round-up will not kill the bulbs in the first application because of the lovely large size of your bulbs. The foliage will soon die back. Both plants and the number and size that you have would cost you a pretty penny to purchase like IBI implied. Looks like you have inherited an old established garden. You might want to get the expertise of a Master Gardener to help you with identifying your gold mine in plants. Looks from the pics some of those other weeds are perennials also. It is getting a little late, but this time of year there are many charitable organizations that have plant sales that might want to harvest some of your perennials and bulbs that you don't want. IBinsanity id'ed the centura.
Tilling up the area will not stop the plants, plus tilling the ground is not the healthiest thing to do for the soil anyway. You really need to pull them up and if you really do not want them or would like to get rid of a lot of them call around to find charitable organizations like Jewel recommended. A local garden club might even come over and dig them up for you. Or offer them on a rEcycle or freecycle list, many gardeners will be happy to come dig them up for free.
Rototilling the garden, rake and level it and then put turf down is what we've decided on. Hopefully the old plants won't grown up through the new lawn! If the garden wasn't so out of hand we might have considered salvaging it. But 7 years of renters who let it go wild is more than we're capable of bringing it back. I'll check some of those sites and post for gardeners who might want some new plants to dig up. There's aloe throughout the property too that we've been digging up and disposing. I thought we had it all but I see some plants still in there yesterday. Our priority this summer is pulling out the old picket fence and putting in chain link in the back yard. Once the fence is cleaned up we'll be putting in the turf.
Funny thing, one mans weeds is another mans flower. To me, bluebells in the first are a joy and I have them colonised all over my garden. The cornflower I also adore, that haze of blue in the mornings is a delight in my front garden and they will grow where other things struggle so I welcome them. If you leave any bulbs or roots from the Centaurea in the ground and lay turf over them, they will still happily grow through. If you really want rid, digging or weedkiller is the only way to go. Rotovating over the centaurea will only chop up the thick roots, multiplying your problem.