St augustine grass is commonly used for partial shade area (3-4 hours of direct sun or all day of filtered sun). If you have a lot of money to burn, check out Shadow Turf. Diamond zoysia may be similiar to Shadow Turf but there's no way to know unless you try both. They will blend in with bermuda much better than st augustine grass.

Almost any cool season grass will suffer in the summer heat if it doesn't get enough water. KBG probably needs more water to stay green than some of the alternatives. Some fescues can get by with somewhat less water than KBG, but they'll still go dormant in the summer with no water. If you want a cool season grass that will stay green with no additional water, I think your best bet would be a native grass like western wheatgrass. Despite the name, it does extend as far east as Ontario. The drawback is that it is somewhat blue green instead of the green of a traditional lawn grass. It can also be rather difficult to get started. If you want a traditional lawn grass with a traditional lawn grass color, you'll need to water it to keep it green in the summer. If you don't mind a different color, something like western wheatgrass may do the trick.

Review your many watering practices. Pick the one that looks most like this: Water deeply and infrequently. Deeply means a full inch (as measured by a tuna or cat food can). Infrequently means once a month this time of year gradually changing to once a week during the hottest part of the summer. You'll have to measure your own sprinkler to time how long it takes to get an inch. Mine takes 8 full hours. My neighbor's takes 20 minutes. Once you know that information, try watering a full inch and adjust your water frequency according to how long it takes your lawn to look withered. Don't water just because you haven't watered recently. Water when the grass looks dryish. With St Aug that is a fragile time. Water at the first sign that any of the lawn is getting dry. Mow St Augustine at the mower's highest setting. If you can go 2 or 3 weeks in between mowing, do that. I have a St Aug yard that has not been mowed in 14 months and, if you like tall grass, it looks great. It seems to have stopped getting longer at about 30 inches tall. You don't need to do that but I can tell you that 2 inches is way too low, 3 inches is still too low, and 4 inches is lower than I like. The taller the better especially out in the full sun. Do not ever till your lawn. If you ever get that urge, stick your finger in a light socket until the urge goes away. If you till it you will be mowing a progressively bumpier and bumpier lawn for years to come. Jackalleness is new to this forum. He lives in Oz and apparently is not familiar with St Augustine. It does not grow from seed. Maybe they do things different down under.

I'm growing hosta, astilbe and lady's mantle from seeds I harvested from my own plants and winter sowed. Pulmonaria (lungwort) is another shade lover, as is black snakeroot, Japanese painted fern, bleeding heart, Japanese sedge grass (carex), and toad lily (tricyrtis). My full shade area is packed with all of the ones mentioned so far on this thread. Brunnera (Siberian bugloss) 'Jack Frost' is going gangbusters in that bed as well but I've never had any volunteers and I hear it's not worth trying to grow from seed. They're gorgeous plants for the shade but they're pricey at the garden nurseries. The one I have is 'Jack Frost.' Best way to get more of them is to grow one & divide it every 3-4 years. Another one that's pricey but does produce seeds is Lenten rose (Hellebore), so named because it blooms during the season of Lent, very early. It's evergreen too. I WS coral bells seeds I got in a trade but got zero germination. I may try to harvest seeds from my own plants this year and try again. I figure since coral bells were the ONLY seeds out of 44 different, new perennials I WS, I should probably try at least one more time. The hosta I WS are doing great but they're not variegated like the parent plants. That's the downside of WS hosta seeds--chances are you'll get plain green ones but they're still free plants! They take time to get any size on them--3-4 years minimum. They don't need cold stratification--I grew some last summer in a sunny window, wintered them over and they're back up again this year, albeit still small. For moist shade, turtlehead (chelone) is nice. I WS seeds and have some nice size sprouts. I WS the white since the butterflies supposedly prefer them over the pink. Don't forget hydrangea--the "hydra" part of the name is Greek for water. They want some shade too and there are gorgeous new cultivars coming out all the time. Lamium makes a nice groundcover for shady spots along with ajuga if you don't mind it spreading everywhere. Creeping myrtle seems to thrive wherever it's planted--I've got it growing in full shade, full sun and everything in between.