Zone 4b: What Grows and How to Garden There

What a zone 4b winter means

Zone 4b is the warmer half of zone 4, but its winters still decide what lives. A good rule from Utah State Extension: hardiness maps miss a lot of local variation, especially in the mountain West, so if you are unsure or the plant matters to you, plan for a colder zone than the map shows. Snowless cold snaps and freeze-thaw cycles in mild spells do most of the damage. Winter mulch, applied after the ground freezes, keeps the root zone frozen steadily rather than heaving.

Where zone 4b is

Zone 4b covers central Minnesota, including Duluth, St. Cloud and Rochester; northern and central Wisconsin around Eau Claire; eastern South Dakota; much of Montana including Great Falls and Helena; southern Wyoming around Laramie; northern Michigan; northern New York; Vermont and New Hampshire’s uplands; and much of Maine. It also reaches northern Iowa and high valleys in Colorado and Idaho, and parts of southern Alaska such as the Kenai Peninsula around Soldotna.

Fruit trees and small fruit

• Apples: SDSU’s list for disease resistance and storage includes ‘Chestnut Crab’, ‘Zestar’, ‘Sweet 16’, ‘Honeycrisp’, ‘Cortland’, ‘Freedom’, ‘Liberty’, ‘Keepsake’, ‘Redfree’, ‘Frostbite’, ‘Regent’, ‘Haralson’ and ‘SnowSweet’. Hardy dwarfing rootstocks are an option with snow cover.
• Pears: ‘Summercrisp’, ‘Ure’, ‘Golden Spice’, and SDSU’s ‘Gourmet’ and ‘Luscious’.
• Plums: ‘Underwood’, ‘Black Ice’, ‘LaCrescent’, ‘Waneta’, ‘Pembina’ and ‘Pipestone’, with ‘Toka’ as a pollinator; ‘Alderman’ and ‘Superior’ suit the warmer parts of South Dakota.
• Cherries: tart ‘North Star’, ‘Meteor’ and ‘Mesabi’.
• Grapes: hardy hybrids. SDSU notes all the cultivars it lists are self-fruitful except ‘St. Pepin’.

Perennials, bulbs and shrubs

Lilacs, rugosa roses, peonies, daylilies, hostas and Siberian iris are dependable. Plant crocus, daffodils, tulips, snowdrops, Siberian squill and grape hyacinths in fall (University of Vermont). Hybrid tea roses need protection: Wisconsin Extension mounds soil over the base and adds a 12-inch layer of leaves or straw.

Short-season vegetables

Iowa State suggests early varieties such as ‘Early Girl’, ‘Stupice’ and ‘Sun Gold’ tomatoes, ‘Red Norland’ and ‘Superior’ potatoes and ‘Early Sunglow’ sweet corn, along with transplants and black plastic for warm-season crops. Hot caps protect only to about 29-30°F, so have row covers ready for late frosts.