Breaking Up Horizontal Lines
A ranch home is primarily distinguished by horizontal lines. With just one story, even L-shaped ranches typically have facades that are much wider than they are tall. Select plantings for your yard accordingly, picking enough taller, narrower plants to break up all the horizontal lines. However, avoid excessive contrast of extremely tall and narrow plants, such as some varieties of cypress.
Whether you're going for a neat, formal look or a more naturalistic setting, select a varied mix of plants. The traditional ranch house is designed with a fairly neutral, anonymous look in the front yard, with more extensive and personalized gardens in the back. Particularly when you're designing the secluded space of your backyard, select plants with a range of textures, including large and small leaves, glossy and matte foliage and contrasting shades of green. If you live in a cold-weather environment, include both deciduous and evergreen plants in your yard to ensure year-round color.
Plants for the House Perimeter
Even if you like a fairly straightforward, grassy yard, you'll most likely want to put some other plants along the edges of your ranch home. For an L-shaped ranch, you have to deal with more angles and more varied growing conditions than in a basic ranch. If you plant anything in the inner corner of the "L", expect generally shadier conditions than elsewhere around the house, unless that corner faces south. If you wish to plant any delicate species, the inside of the L is a good place for plants with fragile flowers that tolerate wind poorly. Since you have a one-story home, pay attention to any bedroom windows when selecting plants. For example, putting a spiky cactus right underneath your bedroom window may be inconvenient, should emergency evacuation prove necessary.
The ranch home has its origins in the mid-20th century, following the Arts and Crafts era and closely mimicking the landscape-hugging forms of traditional 19th-century "haciendas" or "ranchos" in California. As a general rule, avoid pairing a ranch house with a highly contrasting, anachronistic landscaping style, such as a Japanese Zen garden or an English cottage garden. If you're a big fan of a particular style, consult with a landscape designer for tips on unifying it with your house's overall design.