There are over 400 types of soils in North Carolina, ranging from heavy clay in the mountainous Piedmont region of the west all the way to sandy soils in the barrier islands. North Carolina also has a wide range of climates, from USDA hardiness zone 8 along the coast to zone 6 in the mountains. With this diverse range of soils and climates, a wide range of flowers will grow in North Carolina. The key to planting and growing beautiful flowers in North Carolina is to work within your particular soil type and climate.
Collect up to 10 soil samples from across your property by digging 1 qt. of soil from each location. Place this soil into a bucket and pick out debris, such as rocks, sticks, trash, grass and roots. Allow the soil to dry and then collect 1 cup of soil in a plastic bag. Take this plastic bag to your nearest county extension office. An extension agent will help you to package the soil and will send it to the North Carolina Department of Agriculture's soil testing facility for a small fee. Test results are usually returned in three weeks. The results will indicate your soil's pH, nutrient content and structure; they will also recommend soil additives and amendments to improve the soil.
Prepare your soil for planting by breaking up the soil with a rototiller to a depth of 12 inches. Spread a 4-inch layer of organic soil conditioners (such as peat moss) and organic fertilizers (such as compost) over the soil. Peat moss will help to aerate and improve drainage in heavy clay soils (such as the kind found in the Piedmont area), and will help to trap moisture in sandy soils (such as the kind found in the Barrier Islands). Add sulfur to lower the soil pH; add lime to raise it. Most flowers grow best in neutral or slightly acidic soil ranging from 6.0 to 7.0. The soil test will indicate how much of each soil additive you should use and how often to apply it.
Mix soil conditioners in with a rototiller.
Select flowers for your soil based on their performance in your USDA hardiness zone. USDA hardiness zone maps are typically printed on the back of seed packets and flower care tags. You can also find them in many gardening books, your county extension service or on the USDA website. Treat tropical flowers such as impatiens and hibiscus as annuals. Plants that are hardy to your USDA zone will return yearly on bulbs or roots that survive the winter in the ground.
Dig a planting hole in the soil for your flowers that is twice as wide as the plant's root ball. Most flowers prefer to have the top of their roots even with the soil line. Bulbs prefer to be planted at varying depths, while rhizomes and crowns thrive when their tuberous roots are above the soil. Dig a furrow for seeds in the soil with a rake or dowel rod.
Plant seeds twice as deep as the seed's diameter at the widest point. Place the root ball or bulb of flower plants into the planting holes. Cover with soil and water so that the soil is as damp as a wrung-out sponge. Water the plants any time the soil does not receive sufficient rain to make it this damp.
Mulch around the flowers with straw or wood chip mulch to prevent grass or weeds from becoming established around the plants. Grass or weeds will steal water and nutrients from the flowers.