flora2b gives good advice. Round up won't kill anything that doesn't have living tissue above ground. The little bulblets on the dying stems can grow into large bulbs in future years and bloom nicely. But you will probably want to remove them and replant them in a nursery bed until larger. Replant them an inch below the surface. BTW, you don't actually have crabgrass, as that is an annual plant that comes from seed each year. But that really doesn matter, because you still have what you have: quack grass, wild fescues, or some other unwanted grass that is perennial(the same plant returns year after year). You may need to apply Round up more than once, since the root mass underground is usually massive compared to the topgrowth. Consequently not enough round up can be absorbed to do the job with one application. Do not cultivate until the unwanted grass is dead. Otherwise you will end up with many more grass plants to kill.

Sage beush in the high desert. - Native Plants Forum - GardenWeb Seed or perhaps cuttings. I'll try both.

Well, I can add to everyone's excitement by noting that Salvia bucharica, found in Afghanistan and to the north and west, is the old world equivalent, with rose bracts and blue tubular flowers. It is in the section Schraderia, which includes a lovely Turkish species (S. hydrangea). These were once considered a separate genus. The equally elusive S. cadmica (yellow flowers) from Greece and Turkey also has large bracts. This is sometimes sold as Greek mountain tea. Searching this info has caused at least a momentary lusting for Turkish and Iranian sages, the second greatest area of Salvia development after Mexico. Alas, I have to leave these to arid area gardens like the Denver botanical Garden, which has done the best job of keeping Jim & Jenny Archibald's collections alive. Many of the collection areas are now too near Iraq and the Kurdish areas of Turkey. Dr. Ian Hedge of RBG Edinburgh told me of an unhappy incident with a Turkish army patrol which they came across by accident. This resulted in having the many exposed rolls of film of Salvias confiscated. Good luck finding anyone willing and able to collect in Iran, either.

What exposure does the porch have? Morning sun, afternoon sun, or what? Red Yucca and the yellow variety of it would work. Ocotillo, although slow-growing, provides a see-through screen. Desert Milkweed can get 3-5 feet tall, and is a very "stalky" thing. I like the idea of a mass of a single plant. If you have sufficient shade (north-or east-facing porch) you can grow Ficus benjamani in the ground as a screen.