When it comes to choosing plants for landscapes and gardens, it all boils down to one simple task: choosing the right plant for the right place. Well, maybe that doesn’t sound so simple, but with a little knowledge and guidance from resources like this one and some input from friends who garden, a staff person at your local garden center, or other landscape professionals, you can make good choices when it comes to selecting the plants you want to grow and where you want to grow them.
Every plant has a native habitat—a place where it grows naturally or “in the wild,” if you will. Understanding a plant’s native habitat, whether it’s in the open field just behind your house, on the side of a mountain next to a running stream somewhere in China, or in the full sun in an African desert, will help you make the right choice when it comes to selecting the right place for it in your landscape. First, you need to be sure that the plant you want to grow is actually hardy where you live. But what does “hardy” mean? It can mean a lot of things, but when we’re talking about plants, it usually refers to a plant’s ability to survive the winter in your climate, wherever that may be. For instance, palm trees that thrive on the coast of Florida probably won’t last long outdoors after the first frost in Chicago. It’s just too cold and they are not winter hardy.
The USDA (U.S. Department of Agriculture), through many years of research, has come up with a hardiness zone map, which, while not perfect, is extremely helpful for gardeners trying to determine which plants to include in their landscapes. You simply look at the map, figure out which hardiness zone you live in, and then choose plants that are winter hardy to at least your zone or colder. The coldest zones, of course, are farther north and are represented by the smallest numbers—Zone 2, for instance—and as you travel south or west into the warmer regions of the country, the numbers increase. Zone 9, for instance, runs along the Gulf Coast and other coastal regions, as well as parts of the West and Southwest. Most plant labels or reference materials will list a plant’s hardiness zones. Once you know which zone you live and garden in, you’ll have a basic guide to which plants might grow well for you, or at least will survive your winters.
There are entire books dedicated to soil, and it can be a complicated subject. For most homeowners, the question boils down to whether your soil fits into one of three broad categories: sand, loam, or clay. Sandy soils tend to lose water and dry out very quickly and retain very few nutrients, so watering and fertilizing is key to plants thriving in them. Those blessed with good loam are the luckiest gardeners because loam is just the right combination of sand and clay, but with plenty of organic matter that makes the soil rich and water retentive, yet porous and well drained. Water, nutrients, and air are exchanged freely in loamy soil and plants thrive. Then there is clay, the bane of every gardener’s existence. Clay is the smallest particle of soil, with jagged edges that lock together like puzzle pieces, excluding water and air and binding nutrients so tightly that a plant’s roots are unable to pull them away. Without water, air, and nutrients readily available to their roots, plants soon begin to struggle and may die if the situation becomes dire enough.
Both clay soils and sandy ones should be amended with large quantities of good organic matter such as compost, well-composted manure, decaying leaves, and so forth. Organic matter will improve the water and nutrient-holding capacity of sandy soils, and it will help to loosen tight clay so that water, air, and nutrients can reach the plants’ roots. Even good loam should be replenished regularly with organic matter so that the soil’s microbes and its physical structure are well maintained.
When choosing plants for your landscape, further consideration must be given to sun and shade, as well as the microclimates that exist in every yard.
Sun and shade come in varying degrees, but for the purposes of this book, we’ll break it down into four basic categories: full sun, part sun, part shade, and shade.
Full sun can be defined as any part of your yard that receives more than six hours of direct, uninterrupted sun each day (for example, from 7 a.m. until 1 p.m. without the shade of any overhead trees or nearby buildings).
Captivating combinations of foliage provide color and texture in the garden even when plants are not in bloom. This is especially true in shadier nooks where foliage reigns supreme. Here, golden bleeding heart, Dicentra spectabilis ‘Gold Heart’, mingles with false Solomon’s seal, Maianthemum racemosum, the two complementing each other both in texture and color well into the summer and long after each has finished flowering.
Having success in the garden is all about choosing the right plant for the right place. Plants such as the whale’s tongue century plant, Agave ovatifolia, are native to dry regions with desert-like climates. In colder climates, where century plants may not grow, winter-hardy plants such as yucca make perfect substitutes.
Part sun is defined as any part of the yard that receives four to six hours of sun each day, but may be shaded at certain times. Many gardening books reference plants that do well with “morning sun.” This is another way of saying that a plant thrives in part sun.
Part shade is an area of your yard that receives some sun during the day, but it is limited to less than four hours of direct sun. It may also be the very bright shade under a high tree canopy—dappled shade, if you will—where sunlight streams through but is broken by overhead branches and leaves.
Shade is any part of the garden that receives little or no direct sun, but is still light enough for certain plants to grow. It can be found under denser tree canopies that cast even shadows across the ground throughout the day or alongside buildings—especially the north side—where ambient light is present, but direct sun never shines. Shade can be divided into further degrees, but that is beyond the scope of this discussion.
Microclimates are just what the word indicates they are—tiny climates. These are found all around your house and yard, and even within your garden. Buildings create microclimates, larger plants create microclimates, and some microclimates, like those created by a north winter wind, exist naturally. In some Southern gardens, for instance, homeowners may have success with shrubs such as lilacs, which typically don’t thrive in the South, if they place them where cold winter winds prevail. Gardeners up north can use the south side of the house to take advantage of winter sun and warmer microclimates to grow plants that might not be as winter hardy.
Until you understand how hardiness, soil, light requirements, and microclimates all affect your plant choices, you can choose plants all day long and they may not thrive where you want them to grow. Armed with this knowledge, you can now choose plants based on the part of the country where you live and your basic soil type.
Now for a word on actually choosing good plants when you visit the nursery or garden center: choose plants that have an overall healthy appearance. Good plants sit tight in their pots (or rootballs, if you’re buying trees or shrubs that are balled-and-burlapped) and have good color—usually green unless a plant is grown for its colored foliage. Whatever the color, it should be bright, clean, and vibrant. If there are brown patches or if the color is off somehow (pale or grayish), the plants may be stressed or otherwise unhealthy. Also look for spots, white patches, or rings on the leaves that may indicate fungal diseases, as well as any insect pests that may be tagging along.
On small plants—annuals and perennials, in particular—don’t be afraid to inspect their roots. Turn the pot upside down. Can you see healthy, vigorous, white roots through the holes in the bottom of the pot? You should. Gently push your finger down into the soil in the top of the pot. Is the plant so rootbound that you can’t get your finger into the soil? If a plant is that rootbound, it’s going to need a little extra TLC when you plant it, cutting through a few of those roots with a sharp knife to encourage new ones to grow out into the soil.
Finally, look for the plants that appear to be part of the most recent shipments. In spring, this is rarely a problem because retailers are selling plants so fast that new shipments are arriving almost daily. As the season progresses, though, and business slows down, those plants will sit on the shelf longer before they are sold and their health and well being are entirely at the mercy of the staff that cares for them. The less time they’ve spent on the shelf, the more likely they are to thrive once you get them home.
Now that you have a basic understanding of selecting good plants for your landscape, let’s talk about planning for their long-term use and the future of your garden.
Annuals and biennials are important in every garden. The seasonal color and interest they provide is indispensible, and while there is some associated cost with adding new plants each year, they provide longer seasons of bloom than almost any perennials. Many, such as foxgloves, Digitalis purpurea, will reseed themselves throughout the garden for many seasons.