Unwanted grass in garden

Recently planted a rose garden also added bulbs.
I tried getting all the grass out but, didn't do a good job.
Friends told me to put black plastic down for weed and grass growth. Can't do that bulbs are scatterd.

I did put lic.root as a cover.

Tried Preen as all the landscapers here use it, so I'm told.
Any suggestions. Would prefer going organic.
Thanks all.
Happy gardening.
Sandy

A great natural mulch for those of us near the ocean is salt marsh hay. I go to the marsh at low tide and fill trash barrels with the dried grass. It's usually entwined with dried seaweed and molted crab shells- great things to build the soil!

All I use is mulch...Cedar chips because it's native to this area...I use a thick cover of it around the plant, taking care to keep it away from the roots....The only real trick to keeping grass out is to make sure you pull up all the roots. A couple tricks for next time...If you plant in the spring: lay down plastic or cardboard on the area you want to plant (do this during the summer)...weight it down with rocks and leave it there all winter...by the spring when you're ready to plant, remove the plastic and I promise there will be no grass to deal with, then mulch around the plants. Mulch is great because it doesn't prevent the bulbs from coming up...You can recycle plastic or cardboard by laying it down for paths in your garden, the cover it with clean, fresh soil...no grass ot weeds to deal with!

When I want to kill the grass and make a bed, I put down 7-8 thicknesses of newspaper, and cover with 3" of mulch. Works much better than when I used the breatheable weed cloth which always let the grass come through. The first time I did this, I had a decent plantable area within 3 months, but I also kept it somewhat moist so the paper would rot.

I haven't tried this with bulbs already in the ground, but by the next planting season, the newspaper has become mulch, and newly planted bulbs come up fine through it, and no grass.