Hi pinkgator, Can you be more specific about where you live? Is it zone 9a or 9b? Makes a big difference to some of these plants. In your choices, astilbe is unlikely to do well as it needs more cold. Philodendron you have to look up the type individually for cold tolerance, but if you are 9b, there are many types that would work under your oaks. Leather ferns need a lot of moisture and would be unlikely to get that under oaks unless you sprinkle quite a bit or are able to water it with a hose regularly. Liriope are likely to do well. Caladiums are tricky. If you live in 9b, they have a decent chance of coming back each year. In 9a, I doubt it, but you could plant them as annual bulbs and they would be beautiful under oaks. I am in 9b/10a Sarasota, and I have loads of oaks. I have variegated ginger, understory palms (chinese fan palms, wallichias, arengas, cabada and several others), many types of philodendrons, bird's nest anthuriums, landscape begonias, white bird of paradise, firespikes, pentas, macho ferns, fishtail ferns, holly ferns, heliconias, cast iron plants for extremely dry, non-irrigated areas, beautyberry bushes, wild coffee, brunsfelsia, cycads (dioons, encephalartos, zamias, coonties), powderpuffs, crotons, acalyphas,shrimp plants, justicia golden flame, and many others I'm sure. The trick is to not disturb the roots when you plant, choose something that won't require much irrigation (live oaks can decline if they get pampered too much with water, thick mulch, added soil on top of roots), and add as little as possible in terms of additional soil or thick mulch. I love Meem's garden (Hoe and Shovel). In that photo you see variegated alpinia zerumbet (ginger), liriope, dianellas, landscape begonias (red and large round lily-pad types), holly ferns and saw palmettos. Browse her site and you'll get loads of ideas! Good luck and have fun. Anna

I'm afraid you can suffocate your tree if you add more than 2 or 3 inches a year of soil and etc. over the roots of your trees. Been there, done that, and I am still paying for it even after I removed most of the soil. Having said that I have a whole garden area under my oak tree including pathways. The soil should be in good shape because of all the leaves (that's if you left the leaves on the ground) that fall and decompose. I have planted all types of tropical plants and salvias under this tree. If all your trees are fairly close you may want to add a landscape design that includes, if you have it, some of your sunnier areas. This will be different from just putting circles around each tree. This may be a larger project then you may want to take on but it can be done a little at a time. The feeder roots of your oak tree are usually around 12" deep so I would stick with putting smaller starts of plants in, one gallon size or less. Stay away from the 3 gallon size. Good luck and remember if you are not happy with the way the plants look you can always change it.

The most shade tolerant varieties of St. Augustine are Bitterblue, Deltashade, Captiva, Delmar and Seville. Floratine, Classic, Jade and Raleigh varieties also do well in the shade. Similar sounding Floratam and Floralawn are NOT as shade tolerant. All St. Augustine varieties are more shade tolerant than other lawn grasses. Tree leaves are meant to be the mulch that prevents other plants from growing. The leaves break down to feed microbes which make soil nutrients more available to the tree. The problem with live oak leaves is that they are leathery and take much longer to break down, and they smother any emerging plants when they drop in the spring. I have had good results with Holly Fern (Cyrtomium falcatum) under my mature oak. I do have to water these twice a month in the summer in Central Texas.

I was going to say Shooting Stars" - Dodecatheon meadia, but the rest is wrong. I remember one called something like White Dove or White Bird, but don't know much there.