I have no experience with thyme, but I read in my handy Florida gardening book that thyme doesn't do well in summer heat so maybe it is not the best grass substitute? I think that perennial peanuts and sunshine mimosa do well in that capacity although they don't look too good in the winter.

I had the Sunshine Mimosa for a few years but took it out. It looked good in the summer but during the winter it was very sparse and the weeds would pop up between the runners. I put in some Alba Begonias in that area, time will tell if they do well. My neighbor and I planted some Baby Sun Rose ( Aptenia Cordifolia) in our swale where it was hard for grass to grow. It's spreading slowly but we like it so far. Perennial Peanut is another ground cover that you could use and you can mow it if necessary. I would remove the grass but then I always do things the hard way. Someone else might have a better suggestion for you.

Funny thing about that Mimosa-my folks had lived in Fort Myers for twenty years when, upon visiting them, I pointed out this neat, puffy-looking flower growing in the turf on some hell-strip by a mall. They had never seen it! I saw it my first day down there! I guess it's safe to say, the world is composed of two types of people, those who notice plants and those who don't. To wit, if you'll allow me to take this slightly further OT- a botany professor who writes a good blog was writing about his first-day students. He would show them a photo of some scene in a forest somewhere, tropical or otherwise, and ask them to write down what they saw in the picture. Almost to a student, if there was some kind of animal in the picture, it got written down. Nobody....not one student....took note of all the plant life in the photo! And this was a botany class. Sheesh..........I don't hold out a lot of hope for our future. In any case, sunshine mimosa is one of those subtropical plants that, when I'm down in FL I like to look at and conjure up the dream of using it in the north here as an annual. Not saying that would work, or that I'm going to be doing it, but just that it always makes me think about doing so. +oM

And for a completely differing opinion....."Does just mulch look weird?", my answer would be not at all :-) There are all manner of mulches and some are better suited for some applications and locations than others and will have differing aesthetic qualities. Not all mulches will look "dead". I would also argue that nature does not necessarily cover all bare surfaces (other than rock) with plants. In many cases, the soil is covered by layer upon layer of discarded plant matter - fallen leaves and tree needles, dead annual vegetation, pieces of limbs and twigs, etc., forming a naturally occurring mulch that restricts or inhibits unwanted growth while nourishing existing plants I would also ague that some gardeners or homeowners do not want a solid, unbroken expanse of plant material. They prefer individual plants to be distinct and many even prefer that the plants never touch each other. And many groundcovers can be overly aggressive spreaders, requiring more time and attention to control than a typical mulch. Would I use mulch in place of a lawn? Generally, no. In that case groundcover plants might make more sense. Applied organic mulches - shredded bark, wood chips, leaves, certain seed or nut hulls, even compost or manures, etc. - are of huge benefit to a garden in that as they decompose over time, they release valuable plant nutrients and stimulate soil biology. They also help to retard weed growth, slow soil moisture evaporation and insulate both plants and soils against temperature swings. Groundcovers are just living mulches. But they are not the only solution nor necessarily the best. It all depends on one's preferences and application situation.