1. Buy the best plants
Look for plants that have healthy foliage and no roots creeping out of the nursery container’s bottom drain holes (which means they’re probably rootbound). When you have a choice, buy little plants (in 4-inch nursery pots); they’re less expensive (usually under $5), easier to handle, and will catch up to the larger ones with winter rains. Smaller plants are your best bet if you need multiples to fill out a bed. Gallon-size plants, on the other hand, start around $10 each but can provide instant effects.
2. Check the tags
Find out how big the plants will grow, and whether they need sun or shade. Then choose plants that will thrive in the spot you have in mind for them. “Full sun,” for example, means you should plant in a spot that gets at least six hours of sun a day.
Unless you have your own compost pile at home, or perfect garden soil that drains well, buy bagged compost to add to the soil before planting annuals, edibles, and many ornamentals (trees and native plants generally do not need added compost). It’s often sold at nurseries in 1- and 2-cubic-foot bags, and in bulk at garden suppliers. Avoid bagged compost that looks as though it has been piled and stored in hot sun for months—it won’t do much for your soil.
4. Improve your soil
Dig up the existing garden soil to a depth of about 10 inches, breaking up clods and removing stones as you go. Then (unless you’re planting trees or natives) spread 4 to 6 inches of compost over the area and dig it in. Rake the soil until it’s level and smooth.
Set up a watering system if you don’t already have one. Drip is ideal for many plants, but soaker hoses or hose-end sprinklers work too. Water plants still in their nursery containers with a hose before planting.
6. Provide room to grow
Allot plants enough space to reach their full sizes (when in doubt, read the label). It’s tempting to cram them closely together when they are small, but a crowded plant never grows well.
Slide the rootball out of the container and gently loosen the roots on the sides with gloved hands. Using a shovel, dig a planting hole that is roughly twice as wide as the rootball and about as deep. Set the plant in the hole. Trees, shrubs, and perennials should sit about an inch above grade to allow for settling; annuals can be flush with the ground. If your native soil is loam and drains well, backfill the hole with it. If it’s sandy or heavy clay, mix compost into the backfill (except when planting trees or natives).
8. Spread mulch
To prevent weeds and help retain moisture, lay 2 to 3 inches of mulch (such as fine bark) over the soil around plants. Avoid piling it against trunks, crowns, or stems, as that can cause rot.
9. Nurture new growers
All young ornamentals—even natives and drought-tolerant choices—need deep watering right after planting. Irrigate them deeply and thoroughly with the hose, even if you plan to let drip irrigation take over later. Give them regular water through the winter if rains are slight, and then beyond until they reach maturity at a year or two.