I have been doing a lot of research on plants that don't need a lot of water since we bought a 3 acre property in lake mathews, ca. Here's what I have so far...verbena rigida, creeping raspberry...both spread very fast and require little water. I will be buying these for our slopes. delosperma cooperi is similar to ice plant but very hardy and does not require as much water.... Ice plant requires a lot of water and its heavy. That is what we have currently and we will be replacing it with what I have written here. All our slopes have ice plant and we are trying to save water costs. So I will be adding those ground covers and adding water wise bushes and other plants. Snow in summer also sounds like a good plant to add. They say it spreads fast and it's very nice... I also want to add fremontodendron, it looks like a nice bush to add...since we have so much room... Any other ideas?

The least expensive way to get your certificate is probably to mulch the entire slope and plant a few plants on it. I would choose a couple of species that you like (I'd stick with only native plants because I like them, they are better for wildlife, and because many won't require water after this year) and plant smallish individual plants. With such a large area, youll need lots of individual plants, so start small and spread them out a little. With a thick layer of mulch your soil will be stable for a while untilt he plants grow in. Make sure that you do not allow runoff from above to run down the slope because this will cause erosion. I think you've gotten several good suggestions for plants. Baccharis (Coyote Brush) is a nice, tough, evergreen plant, salvias of several species are colorful and great for hummingbirds (see the Las Pilitas website for ideas), California buckwheat (eriogonum fasciculatum) is easy and attracts butterflies, and a California Fuchsia adds great late-summer color. For a large slope like this you might add Climbing Penstemon (Keckiella cordifolia) as a great summer hummingbird plant - slopes are the best place for this plant as it sort of cascades in its natural form. You've got the space for a great hummingbird/butterfly garden here. I'd start with mulch and the minimum number of plants that will meet the requirement, and add things as you see what thrives and you have more time to think about what you want to grow.

Your pics look very similar to my back yard! We have to get more gravel this year too. Ornamental grasses, bigger rocks(they don't cost much), SHREDDED pine mulch and day lillies. Water the hill at a flat setting on the nozzle. Get that ornamental grass and day lillies in fast though. Man, you can get some bad summer storms and you will have erosion on the sides, you need roots in there tomorrow. There are grasses that prefer shadier conditions, and even some bamboo that are dwarfs, short, that will do an excellent job for you taming that hill. Good Luck! It's alot of work!

If you live in New York as suggested in your name, you might want to search on cliffandjoann. They built a stunningly beautiful pond and have explained the details. They say that some of their plants are in pots. I use impatiens and am under the impression that they will grow without much actual soil. It is certainly true for water cress (from the grocery store) anchored directly in flowing water. For something larger, sweet flag will certainly work. You can also use vines or other plants growing beside or near the area. You can also add logs or other natural materials for interest and coverage.