Native plants add to the biodiversity of the world's vanishing wild places. They give even a suburban yard a natural look that can be a nice change from cultivated species such as roses and lawns. When you grow plants that are native to your region, you will be helping to conserve and you'll also be freed from much of the care that many cultivated plants require. Native plants grow where they want to grow and rarely need water or fertilizer. Although it might be difficult to find native plants at nurseries, many seed sources exist on the Internet.
Plan to start seeds in the fall. You can collect some seeds from the wild, but be sure to learn the laws of your state or county regarding the collection of native plants and seeds. It's wise to order seeds from online catalogs that specialize in the native plants of your region.
Try starting your seeds in two different ways: by broadcasting them in an area you want them to grow and by starting them in flats or pots, which gives you more control over the amount of water and light they receive. The plants will teach you what they like--for example, perhaps your California poppy seeds will do better in the garden than in a pot. Experiment to find out what works best and then use that method next year if you want to grow more of the same plant.
Weed the area in your yard where you plan to scatter your native plant seeds. Then loosen the soil with a hoe or rake and scatter your seeds over the soil surface. Press them into the soil with your palm.
Fill nursery pots or flats that have drainage holes with standard potting soil if you want to start your seeds in more controlled conditions. Plant tiny seeds on the soil surface and then pat them down without covering them with soil. Plant larger seeds about a quarter-inch to half-inch deep. Different plants have different germination requirements--if you buy native plant seeds, follow the label instructions to learn the specific needs of each plant. Keep your pots in a sunny area that is protected from frost and keep them moist, but not soggy, for most species.
Watch for germination--when your seedlings are 1 to 2 inches tall, thin them to an appropriate distance apart. For example, if you're thinning an area in the garden, leave 6 to 12 inches between smaller plants such as penstemons, but leave more room between plants that will grow large, such as native trees. When your potted seedlings reach 3 or 4 inches tall and your final spring frost has passed, you can transplant them to the garden.
Propagate some species from cuttings or root division. For example, the Pacific Coast iris is a bulb, so this is a plant that you can propagate by digging up the tuberous root, separating it and planting the pieces. You can propagate penstemons from cuttings.