Ground Cover

I am new to gardening. I have several large areas in my yard where the grass doesn't grow. If there some time of ground cover or ivy that grows quickly that I could use? And where would I get it?? at a nursery??? The area is mostly shade.

Be careful what you wish for, Eileen. Don't create a monster that will run amok and become unstoppable. The English Ivy, as you may know, can be an incredibly invasive nuisance, eventually blocking out the sunning and destroying all life on planet Earth. It's a question of root systems that really take hold and hang on for dear life. Rather than visit a nursery, start by cruising the more established neighborhoods on a nice day when gardeners are out. If you see something you admire, take the time to ask the homeowner about it, or at least note it for further research. Take your camera. I would LOVE to unburden myself of the vinca in my yard, which is selling quite dearly at the Home Depot. Not my creation. I have some unidentified types, as well as an Oregon Shamrock that I unsuccessfully removed from a bed last spring (that just encouraged it). It's BACK! Ajuga is growing in my lawn, so obviously stands up to abuse. Sweet blue flowers in spring and early summer. Perhaps you might consider shrubs or perennials in those areas. No need to corral them, then, and it might be more fun for you.

I just planted ajuga in my garden where the grass is getting thinner and thinner and I want it to take over the whole area, it says you can basically abuse it and survives. If you want to get rid of the lawn that's what I would suggest.
check these out...
http://www.bluestoneperennials.com/b/bp/scan/tf=name/ml=12/ma=1/rf=%2A/co=yes/sp=results_pics/st=db/fi=products/sf=ty/se=tc/op=rm/sf=disc/se=0/op=%3E.html?ext_title=Ground%20Covers

I've read that ajuga is very invasive. So- do you plant it to take over what is already there and just have that as a ground cover instead if grass etc. ??

My recommendation is to look for plants that grow well in the soil conditions where your grass doesn't grow, ideally Massachusetts natives. The "Combination Search" feature at wildflower.org is a great place to get started, once you've figured out your soil type (clay, loam, sand) & light conditions (sun, part shade, shade).

I want it(the ajuga) to take over where the spotty grass is.

Pacasandra is a good choice. One of the things I like about it is it is evergreen it also spreads quickly. You might consider more than one type of ground cover for interest. Lamium and Lysimachia nummularia money wort are both nice choices. The pacasandra has a medium green shiny leaf with white flowers, Lamium is varigated with pink and blue flowers and money wort is bright green with yellow flowers. They make a nice combination and grow well in both shade and sun.

I have found that ajuga grows very slowly in shade, at least for me it does.
Below is a web address for classygroundcovers they have a nice search and you can buy the plants in flats.

http://classygroundcovers.com/cat----PACHYSANDRA-terminalis&affl=google-pacasandra?gclid=COf9xN2Yj5MCFRiDkwod_xjXTg

For some reason I thought pachysandra for sunny areas. I like that too. I'll think I'll have to buy some.

I have the pachysandra in total shade and it is spreading like crazy.