Hi, I need some advice. I have a new house and planted grass seed a few weeks ago. I have excellent soil, but no sprinkler system. The new lawn is coming in slowly, but I have a hard time keeping it wet.
Since the lawn is establishing so slowly, grassy weeds are starting to invade the bare soil, and even amongst the new grass. I tryied spraying them, but that just killed the new grass around them. So, here's my question: Will the new grass out-compete these weeds once I start mowing?? Or will they be in the lawn forever now?? What should I do??
First, welcome to The Helpful Gardener! 
If you're new to forums, you might have missed the Sticky message at the top of the Lawn Care Forum:
https://www.helpfulgardener.com/forum/viewtopic.php?t=1782 (Organic Lawn Care, also aimed at new lawn-keepers)
There are many, many threads re. new lawns, renovating old lawns, taking down weed patches, etc. in the Lawn Forum, as well as several experienced lawn-keepers. When you find a forum member whose advice is helpful, use the Search function at the top left-hand corner of the page to find other posts by that member.
An all-around gardening book, like Sunset's Western Garden Book, will also contain instructions for establishing a new lawn. The Sunset book is aimed at gardeners in the western United States and Canada, and Montana *definitely* is included!
Best wishes for success!
Cynthia H.
Sunset Zone 17, USDA Zone 9
If you're new to forums, you might have missed the Sticky message at the top of the Lawn Care Forum:
https://www.helpfulgardener.com/forum/viewtopic.php?t=1782 (Organic Lawn Care, also aimed at new lawn-keepers)
There are many, many threads re. new lawns, renovating old lawns, taking down weed patches, etc. in the Lawn Forum, as well as several experienced lawn-keepers. When you find a forum member whose advice is helpful, use the Search function at the top left-hand corner of the page to find other posts by that member.
An all-around gardening book, like Sunset's Western Garden Book, will also contain instructions for establishing a new lawn. The Sunset book is aimed at gardeners in the western United States and Canada, and Montana *definitely* is included!
Best wishes for success!
Cynthia H.
Sunset Zone 17, USDA Zone 9
No, ckendall, the new grass will not outcompete the weeds when you begin mowing. What you have encountered is one of the barriers to spring seeding, in that spring offers more weed pressure than fall. Something else is that I expect you planted Bluegrass there in Montana, and Bluegrass is a very slow starter, taking several weeks just to germinate. The problem is the impossibility of growing grass and controlling weeds at the same time, which everyone encounters when in your shoes. My advice is to always concentrate on growing the grass so that it comes in thick and healthy. With proper maintenance, the grass will be able to crowd weeds but not all of them and not until it is well established. I don't expect your spring planting to become a well-established lawn until fall and possibly not until next spring. In the meantime, absolutely do not allow it to go dormant this summer because it is too stressful on the new grass plants and seedlings. You will have to irrigate through the summer to keep it green. Please tell me if you know *how* to irrigate and if you need maintenance tips.