Zone 5b: What Grows and How to Garden There

What a zone 5b winter means

Zone 5b is the warmer half of zone 5. Most perennials, shrubs and fruit sold for northern gardens survive here, and the plants that fail usually do so for one of three reasons: flower buds killed in a hard winter, blossoms killed by a spring frost, or roots and evergreen leaves dried out by winter wind. Choosing the right species and cultivar handles the first. Site handles the other two.

Where zone 5b is

Zone 5b covers southern Wisconsin around Milwaukee and Madison, much of Iowa including Des Moines, northern Illinois outside Chicago, eastern Nebraska, lower Michigan away from the lakes, upstate New York and the higher ground of Pennsylvania, Massachusetts, New Hampshire, Vermont and Maine. In the West it includes the northern Colorado Front Range from Fort Collins to Longmont, western Montana valleys such as Missoula, the Black Hills around Rapid City, and high valleys in Idaho, Utah, Wyoming, Nevada, New Mexico, Arizona and eastern Oregon and California.

Fruit trees and small fruit

Nebraska Extension’s short list for home orchards in the eastern part of the state is apples, pears, tart cherries and plums. Its picks include disease-resistant apples ‘Enterprise’, ‘Freedom’ and ‘Liberty’; fireblight-resistant pears such as ‘Moonglow’, ‘Magness’ and ‘Harrow Delight’; tart cherries ‘Montmorency’, ‘North Star’ and ‘Balaton’; and European plums such as ‘Earliblue’ and ‘Damson’, which bloom later than Japanese types.

Sweet cherries are possible but unreliable. Iowa State grows ‘Gold’, BlackGold and WhiteGold only in the southern half of Iowa and expects a good crop in just 2-3 years out of 5, because they bloom early. Peaches and nectarines often lose their flowers to cold, and apricots bloom so early that spring frost takes them most years.

Hardy kiwi (Actinidia arguta) is an option for a sturdy arbor: Wisconsin Extension rates it to -25°F when fully dormant, though new shoots and flowers are damaged by a spring frost of 30°F.

Perennials, bulbs and shrubs

Iowa State lists peony, daylily, hosta, Siberian iris, daffodil, baptisia and sedum among perennials that commonly live 20 years or more, while delphinium, lupine, coral bells and hybrid tulips often fade within a decade. Daffodils, crocus and grape hyacinths are the bulbs to plant for permanence; Iowa State plants tulips and daffodils 6-8 inches deep.

For hydrangeas, smooth and panicle types flower on new wood and bloom every year. Bigleaf hydrangeas lose flower buds in cold winters (Cornell).

Special concerns

• Winter drying in the West. Colorado’s Front Range winters bring warm, windy, dry days without snow. Evergreens, especially those planted in the past year and those on the southwest side of buildings, turn brown from winter burn (Colorado State, Utah State). Water in fall and during dry spells of a month or more.
• Wet winter soil. Lavender, rosemary and other Mediterranean herbs die from wet roots more often than from cold. Rosemary does not survive outdoors here.
• Spring frost pockets. Plant fruit on ground higher than its surroundings and avoid south- or west-facing slopes that push early bloom (Iowa State).