The Iowa Gardener: How to read a plant label

  Buy Photo

What the heck is part shade? Part sun? Do I have "well-drained soil?" And what in the world is a "zone?“

Plant labels are one of the first things to look at when considering buying a garden plant, and they can be helpful, but they can be confusing and sometimes downright misleading.

One rule of thumb on a plant label: More detail is better. The more informative a plant label is, the overall higher quality you can expect the plant or seeds to be. It indicates that the company wholesaling the plant (or seeds, for that matter) recognizes that a gardener who has good growing information is more likely to have success. So read the label carefully. You'll save yourself many dollars and hours of effort.

Even good labels, however, are limited. Be sure to take a few minutes, as needed, and pull out your smart phone and look up the plants online, or decipher instructions, like "Thin wood to prevent heavy bearing."

A plus: Some labels have URLs or QR codes to scan for more information. However, label writers are also in the business of marketing and can sometimes make exaggerated claims or are unclear, so check multiple sources if you have time, either before you buy or to guide you before you plant it.

Here's what to look for:

Name. Every plant label will have the common name (like “Marigold,” or maybe a little more detail, like “African Marigold.”) It may also have what is called a cultivar, like “Aztec Yellow.“

Look also for the botanical name, the often difficult to decipher — but very helpful —Latin name, like “Tagetes erecta.” Lots of annuals share a common name. For example, think about how many plants have a common name that contains the word rose, daisy or lily, even though they are not any of those. Botanical names help you figure out what you truly are buying.

Zones. The U.S. Department of Agriculture has divided different parts of the country according to cold hardiness zones, and these are on most labels for trees, shrubs and perennials.

Cedar Rapids — and most of Iowa — is in Zone 5. More precisely, Cedar Rapids is on the southern edge of 5a, the colder part of Zone 5. So is Cedar Falls, Iowa City and Des Moines. Iowa City and much of the southeast portion of the state is in 5b, the warmer part of Zone 5.

Up along the Minnesota border, there are a few spots in Iowa that are Zone 4. The only Zone 6 in Iowa is a teeny spot, just south of Keokuk. (See the full map at planthardiness.ars.usda.gov)

Annual or perennial? In most cases, labels accurately tell you if a plant is a perennial (comes back year after year) or an annual (dies after one year). However, look at the USDA zone carefully. Purple fountain grass, for example, is often sold as a perennial but it's hardy only through Zone 7, tops. It will die out in winter in Iowa.

A handful of popular Iowa garden plants are "biennials," which are plants that have a growth cycle of two years. They grow from seed their first year, and then produce flowers their second year. Definitely look online for how to grow any particular one since each one is a little different and very few plant labels give adequate information to help you make your buying decision.

Light: Sometimes called "exposure." This is incredibly important can be confusing. What is part sun? Part shade? Light shade? Deep shade? Full sun?

Take comfort in that even seasoned gardeners struggle to estimate what different types of light they have in different parts of their garden. It's a learning process and even once you think you've got it figured out, a tree gets cut down and you have to figure it out all over again.

One tip: Plant one of the following to test light conditions in areas you're unsure. An impatiens will thrive in "shade," but not deep, full shade. A marigold will thrive in full sun to extremely light shade. The annuals salvias that are usually red, “Salvia splendens,”will thrive in light shade to full sun.

Full sun is six or more hours a day of full sun, no shade and no dappling from trees. However, here in the upper Midwest, with our less direct sun, I feel that full sun plants need at least eight hours a day. Also keep in mind that most gardeners in Iowa, with all our beautiful mature trees, tend to overestimate how much sun a spot gets. When in doubt, assume it's shadier rather than sunnier.

Part sun/part shade or light shade gets four to six hours of direct, unfiltered light. Dappled or filtered light doesn't count.

Shade is less than four hours of direct sun a day, but with dappled or filtered light, or dappled or filtered light all day long. Fewer plants do well in shade than in full sun or light shade.

Full or deep shade may be some direct sun, but otherwise filtered or dappled light. Very few garden plants do well in full shade.

Height and spacing. Usually very accurate. With trees and shrubs, don't kid yourself by convincing yourself that you can prune it to keep it smaller. That usually looks really unattractive and is a ton of work, if you actually even do it. Buy the right-sized plant for the space.

Follow spacing directions to the letter, especially with trees and shrubs. Measure the actual space and plant so it won't grow into a building or overwhelm other plants. With annuals and perennials space as specified so that plants will get good circulation and not compete with each other, growing up as big and healthy as possible.

Soil. Most Iowa garden plants do best in what is called "rich, well-drained soil." That's soil in which water doesn't puddle (a very gentle slope or raised bed is ideal) and looks nice and black and crumbly. If you don't have that, work in as much compost as you can each year.

Care tips. Read with a grain of salt. For example, it might say, "fertilize monthly," but that's extremely subjective. With what? At what concentration?

Many labels have information on watering, like "does well in dry conditions" or "keep moist." You can't, of course, control rainfall, but you can water additionally in dry conditions for plants that like moist conditions. And you can water those that like it dry less.

Try to plant plants with similar needs, like excellent drainage or moist or dry soil together so you can care for them as a group.

With all your labels, it's smart to keep them for a year or more. That way, you have a better chance of remembering what you actually planted, and you'll also have some handy growing information. Wash them off and write the year on them and — here's the hardest part — store them somewhere where you will remember.

  Buy Photo

Veronica Lorson Fowler is co-publisher of the Iowa Gardener website at www.theiowagardener.com.