If you had the rare opportunity to create a new garden in an empty space, where would you start?

Most of us acquire gardens or landscape beds that were never designed; they just grew haphazardly around a house or next to a sidewalk or garage. Even if you started your own garden, you were probably a beginner, or had entirely different interests, lifestyle, tastes or plant knowledge. But let us imagine a blank palette – a well-sited space, with good sunshine and excellent soil, of course – and plan a new garden. What comes first?

First things first

Most design teachers and writers cover shape and structure early in the lesson, because these features greatly define your garden. Whether the bed is square, round, oval or kidney-shaped, it begins to create an identity: Straight lines suggest formality; gentle curves are more relaxing. If there is a path to and from, or through, the space, that, too, influences all future choices.

If you are really making a new garden in the middle or at the edge of a lawn, use a rope or hoses to outline the space. Then step way back from it and look from several angles, especially the primary vantage point such as the deck, kitchen window or street. It may even help to place pretend plants there – baskets, tall houseplants, lamps – to get the sense of a real garden. You don’t have to be an expert to know if that outline, in that space, looks and feels balanced, pleasing and in proportion to the whole yard.

The bones are the big features that dominate the design, usually all you see in winter – trees and large shrubs, especially evergreens, and architectural elements such as a fountain, arch, pergola or gazebo. Decide early what you must have – a bench, a small tree, a bubbling fountain – and place it in the new space. Now you no longer have a blank palette.

The backdrop is whatever surrounds the garden, physically or visually, and it’s usually something you don’t control. Your backdrop could be the neighbor’s garage, your back fence or a view in the distance. If your new garden has no imposed backdrop, you might choose to add a beautiful stone wall, attractive fence or hedge to provide definition. Like a stage set, what surrounds or encloses a space draws attention and adds importance to whatever happens within.

In short, we can’t ignore the shape, bones and backdrop factors. It is so much more fun to get on with the gardening – choosing, combining and planting plants – but design elements will define your garden for years to come. Think it through.

Now for the plants

When the stage is finally set, the plants are the players. Design work is not done, however.

A few plants will have full-time jobs providing the skeletal structure of your garden, sometimes by themselves and sometimes in relationships with solid “hardscape” features. Plan the tall hardscape pieces in conjunction with the choice of largest plants because they have the same jobs: vertical interest, focal points, support for vines, shade or backdrop for smaller plants.

Too many tall things – trellises, trees, giant grasses – makes a space look cluttered, whereas one tall thing draws attention and pleases the eye. Choose your tall feature early, and if you already have the heirloom gas street lamp or Grecian urn selected, you may not need a tree.

If your garden design does call for a tree or large shrub, or several if the scale is larger, an important caveat is in order: Do not fall in love with and choose a tree at a nursery based on what you see before you. How tall and wide will that plant become when it is mature?

Of all the landscape design mistakes that professionals see every day, failure to ask this question is the worse because the consequences are most expensive and disruptive. How many times must we pull out an arborvitae or juniper placed 3 feet from a front door or remove a gorgeous, 20-foot Japanese maple that was put 4 feet from the corner of a house and now blocks half the living room window?

Evergreens and small trees including Japanese maples are now available that actually will remain the size that will suit smaller landscape spaces, but you can’t make a large plant into a small one by chopping it back continually. For your garden bones and focal points, good nurseries do have beautiful specimens that will remain 22 feet tall, but you must read, communicate and understand.

Nearly as important as focal point plants or bones, front-edge or border plants greatly define or frame a garden. A uniform front-edge planting ties a garden together and suggests a plan; it provides comforting uniformity.

The front edge of the bed can be all one kind of plant – a bright coleus, begonias, lamium or sedum. It can be several swaths of different species with the same color foliage or flowers – gray lamb’s ears, dusty miller and snow-in-summer. Or it can be long sweeps of several different kinds of plants, preferably repeating at least one of the groups for continuity. What does not work: one of everything you like that is short, or a dotty every-other-one alternating pattern.

It’s fun to choose upfront plants these days, as garden centers offer so many flowering annuals that you can change every season and low-growing perennials that quickly cover the soil and block weeds. More than in any other part of the garden, choose more plants for the front border than you think you’ll need and put them closer together than you normally would. The front edge makes a strong first impression and makes a garden look finished much quicker than any plants you place within the garden bed.

Rules aren’t really made to be broken; most garden design principles will serve you well. But it’s your garden, and the most important rule should be that your garden should give you joy. Go make a design, and find the joy.

Sally Cunningham is a garden writer, lecturer and consultant.