Planning out how to arrange furniture in your home — or plants in your garden — used to involve a pencil, graph paper, a measuring tape and a lot of imagination.

The process has gotten easier — and way more streamlined — thanks to a burgeoning selection of home and garden apps.

Furniture companies, interior design firms and even landscapers have been rolling out a new generation of apps and online programs to make the process more foolproof for novices and pros alike, often using virtual and augmented reality technology.

“Design apps are really great for generating ideas, and deciding on materials and sources for do-it-yourself projects,” says Margaret Mayfield, an architect in Los Osos, Calif. “And they’re also very helpful for communicating design ideas to contractors and architects.”

The technology allows you to see what furniture would look like in your home before you buy it, using just the camera on your phone, for example, instead of dealing with the hassle — and back pain — involved in returning, say, an ill-chosen sofa.

And the design apps do not stop at the door. There are landscaping apps to help take the guesswork out of deciding what to plant and where and when.

Among the most popular home apps is Houzz, a free app with 40 million users around the world each month, according to Liza Housman, vice president of industry and marketing for Houzz. Features include a huge database of design photos — searchable by style, country or color, for example — to create a personalized “idea book.”

The site’s “Visual Match” feature allows visitors to order furniture and other products that are the same or similar to those seen in the magazine-type photos. You can work with a friend by using the “Invite a Collaborator” feature, or, through “Directory,” contact local designers, architects or landscapers.

One of the newest features is “View in My Room 3D,” which invites you to photograph your room on your phone and then — using augmented reality technology — place a selected piece of furniture in the room to see what it would look like there.

Other indoor design apps include Hutch, Home Design 3D, and Home Design 3D , Rooms, and interior design apps from stores like IKEA and Overstock.com.

For outdoors, Houzz — which recently acquired the GardenWeb app and is integrating it into its own app — features articles and advice from gardening pros, and a forum where home gardeners can share ideas and suggestions.

Another popular landscaping app is iScape, which helps you visualize your garden, save and share ideas, and buy gardening products.

As with all technology, though, the apps have a learning curve that in some cases is far greater than the old graph paper and pencil method of laying things out. And professionals warn that for major jobs, it’s still best to seek out a pro.