Zone 6 gardens get real winters, with lows of -10 to 0 degrees F, and a frost-free season of roughly 150 to 180 days. That is plenty of time for tomatoes, peppers and squash if you start them on schedule, and the cold winters are exactly what peonies, tulips, lilacs, apples and many of the best perennial flowers need. The keys are knowing your frost dates, starting warm-season crops indoors, and choosing perennials and shrubs rated to zone 5 or colder for a margin of safety. Below is a practical zone 6 plant list and month-by-month calendar for both 6a and 6b.
In this guide
Key Takeaways
- Zone 6a lows reach -10 to -5 degrees F; 6b lows reach -5 to 0 degrees F.
- Typical last spring frost is late April to mid May; first fall frost arrives early to mid October. Check local dates.
- Start tomatoes, peppers and eggplant indoors in March; transplant after mid May.
- Zone 6 is ideal for classic perennials: peonies, coneflowers, daylilies, hostas, phlox and bearded iris.
- Plant garlic and spring bulbs in October, and trees and shrubs in early fall or spring.
Zone 6 at a Glance
Zone 6 runs across much of the central and northern US: southern New England and the lower Hudson Valley, Pennsylvania, Ohio, Indiana, Illinois and Missouri, Kansas, parts of Kentucky and the mountains of the Southeast, much of Colorado’s Front Range and Utah’s valleys, and the higher inland Northwest. Because zones only describe winter lows, a zone 6 garden in humid Ohio and one in dry, high-altitude Denver have very different summers. Confirm your exact zone on our USDA hardiness zone map guide.
| Subzone | Average winter low | Typical last spring frost | Typical first fall frost |
|---|---|---|---|
| 6a | -10 to -5 degrees F | Early to mid May | Early October |
| 6b | -5 to 0 degrees F | Late April to early May | Mid October |
Use these as rough guides only. Frost dates shift with elevation, cold air drainage and proximity to large lakes. Your county extension office publishes local averages.
Perennial Flowers for Zone 6
Zone 6 is one of the best climates in the country for hardy perennials. Cold winters satisfy their dormancy needs, and summers are long enough for a big show. These are reliable choices that come back year after year:
| Perennial | Light | Bloom time | Height | Notes |
|---|---|---|---|---|
| Peony | Full sun | Late May to June | 2 to 3 ft | Plant eyes 1 to 2 inches deep in fall; lives for decades |
| Coneflower (Echinacea) | Full sun | July to September | 2 to 4 ft | Native, drought tolerant, loved by pollinators |
| Black-eyed Susan | Full sun | July to October | 2 to 3 ft | Long bloom, tolerant of poor soil |
| Garden phlox | Sun to part shade | July to September | 2 to 4 ft | Fragrant; choose mildew-resistant types |
| Bearded iris | Full sun | May to June | 2 to 3 ft | Plant rhizomes shallow in late summer |
| Daylily | Sun to part shade | June to August | 1 to 4 ft | Nearly indestructible |
| Hosta | Part to full shade | Summer | 1 to 3 ft | Foliage star for shade; deer favorite |
| Catmint (Nepeta) | Full sun | May to September with shearing | 1 to 3 ft | Deer and drought resistant |
| Bee balm (Monarda) | Full sun | July to August | 2 to 4 ft | Native, attracts hummingbirds |
| Sedum (Autumn Joy types) | Full sun | August to October | 1 to 2 ft | Late color, winter seedheads |
| Astilbe | Part shade | June to July | 1 to 3 ft | Needs consistent moisture |
| Aster | Full sun | September to October | 2 to 4 ft | Vital late-season pollinator food |
Other strong performers include salvia ‘May Night’, yarrow, coreopsis, Russian sage, baptisia, hardy geraniums, lady’s mantle, bleeding heart, columbine, lupines (in cooler parts of the zone) and ornamental grasses such as switchgrass and little bluestem. If deer visit your garden, favor catmint, salvia, baptisia, Russian sage and ornamental grasses over hostas and daylilies.
Native perennials deserve a special mention because they are adapted to zone 6 winters and support local pollinators. Good choices for sunny beds include butterfly weed, wild bergamot, New England aster, purple prairie clover, rattlesnake master and blue false indigo. For shade, try wild ginger, foamflower, Virginia bluebells, Solomon’s seal and native ferns. Plant natives in spring or early fall and water them through their first summer; after that, most need little care.
Vegetables for Zone 6
Cool-season crops
- Peas: Direct sow from late March to mid April as soon as soil can be worked.
- Spinach, lettuce, arugula: Sow early April to May, and again mid August to early September for fall.
- Broccoli, cabbage, cauliflower: Start indoors in early March, transplant mid to late April. For fall, transplant in late July to early August.
- Kale and Swiss chard: Transplant in April; both keep producing into November, and kale often survives into winter under cover.
- Carrots, beets, radishes, turnips: Sow April through May and again late July to mid August.
- Onions and leeks: Start seeds indoors in February, or plant sets in April. Long-day onion varieties bulb best in the northern half of zone 6.
- Potatoes: Plant seed potatoes in mid to late April.
- Garlic: Plant cloves in October for a July harvest. Hardneck types are especially well suited.
Warm-season crops
- Tomatoes, peppers, eggplant: Start indoors in mid to late March. Transplant after the last frost when nights stay above 50 degrees F, usually mid to late May.
- Beans: Direct sow from mid May through early July.
- Cucumbers, squash, melons: Direct sow or transplant in late May to early June once soil is warm. Choose melons with 80 to 90 days to maturity or fewer.
- Sweet corn: Sow from mid May to late June in blocks.
- Pumpkins and winter squash: Sow late May to early June for October harvest.
If you garden near the warmer edge of the zone, our zone 7 planting guide shows how timing shifts about two weeks earlier in spring. For plants that only thrive in much milder winters, see our zone 8 plant list, which makes a useful contrast.
Herbs
Perennial herbs that overwinter reliably in zone 6 include chives, thyme, oregano, mint, sage, tarragon, lovage and lavender in sharp drainage, especially hardy English types like ‘Munstead’ and ‘Hidcote’. Rosemary is not reliably hardy; grow it in a pot and bring it indoors. Basil, dill, cilantro and parsley are grown as annuals or biennials.
Shrubs and Trees for Zone 6
- Hydrangeas: Panicle and smooth hydrangeas bloom reliably on new wood. Bigleaf types often lose flower buds to winter cold; choose reblooming varieties.
- Lilacs: Common lilacs and the Japanese tree lilac thrive here.
- Spring bloomers: Forsythia, serviceberry, redbud, flowering dogwood, magnolias (star and saucer types) and crabapples.
- Evergreens: Boxwood, arborvitae, yews, inkberry, spruce, white pine and hardy hollies like ‘Blue Princess’.
- Summer and fall shrubs: Spirea, ninebark, viburnum, weigela, rose of Sharon, clethra and fothergilla.
- Fruit: Apples, pears, sour and sweet cherries, peaches (choose hardy varieties), plums, blueberries, raspberries, grapes and strawberries.
Month-by-Month Planting Calendar for Zone 6
| Month | What to plant or start | Other tasks |
|---|---|---|
| January | Little planting; order seeds and plan beds | Check stored bulbs and tubers |
| February | Start onions and leeks indoors | Prune fruit trees on mild days |
| March | Start tomatoes, peppers, eggplant, broccoli and cabbage indoors; sow peas late in the month in 6b | Cut back ornamental grasses and perennials |
| April | Sow peas, spinach, lettuce, radishes, carrots; transplant brassicas; plant potatoes and onion sets | Divide summer and fall perennials; apply crabgrass preventer |
| May | After last frost, transplant tomatoes and peppers; sow beans, corn, squash, cucumbers | Plant annuals and new perennials |
| June | Succession sow beans and corn; plant pumpkins early in month | Mulch beds; stake tall perennials |
| July | Start fall broccoli and cabbage; sow carrots and beets for fall; harvest garlic | Deadhead perennials; water deeply |
| August | Transplant fall brassicas; sow spinach, lettuce, radishes, turnips | Divide bearded iris and peonies; order bulbs |
| September | Plant perennials, shrubs and trees; sow last lettuce and radishes | Overseed and fertilize lawns |
| October | Plant garlic, tulips, daffodils, crocus, alliums; sow cover crops | Dig and store dahlias and cannas after frost |
| November | Finish planting bulbs before the ground freezes | Mulch perennials and strawberries after ground cools |
| December | None outdoors | Protect young evergreens from wind and road salt |
Bulbs for Zone 6
Zone 6 winters provide ideal chilling for spring bulbs. Tulips, daffodils, hyacinths, crocus, alliums, snowdrops, scilla and grape hyacinths all thrive when planted in October, two to three times as deep as the bulb is tall. Tulips perennialize better here than in warmer zones, especially Darwin hybrids and species tulips. Summer bulbs such as dahlias, cannas, gladiolus and elephant ears are tender: plant them after the last frost and lift them in fall for winter storage. Lilies, alliums and crocosmia ‘Lucifer’ are hardy in the ground.
Plants That Struggle in Zone 6
- Tender perennials: Rosemary, lantana, salvia ‘Black and Blue’ and most agapanthus rarely survive winter in the ground.
- Borderline shrubs: Crape myrtle, gardenia, camellia and southern magnolia often die back or fail; look for specifically cold-hardy selections and sheltered spots in 6b.
- Long-season crops: Okra, sweet potatoes, peanuts and large watermelons are possible but need short-season varieties, black plastic mulch or row covers.
- Figs: Survive only with heavy winter protection or in containers moved into a garage.
Tips for Zone 6 Success
- Respect frost dates. Warm spells in April are common, but so are frosts into early May. Keep row covers ready.
- Warm the soil. Black plastic or raised beds warm spring soil faster, letting you plant warm-season crops a little sooner.
- Extend the fall season. Cold frames and row covers keep greens producing into December.
- Mulch after the ground freezes to keep perennials from heaving during freeze-thaw cycles.
- Choose hardiness wisely. In 6a or exposed sites, pick plants rated to zone 5 or 4 for reliable survival.
- Plant perennials early enough in fall, at least six weeks before the ground freezes, so roots establish.
For bed layouts, crop rotation and soil building, see our vegetable gardening guide.
Frequently Asked Questions
When can I plant tomatoes in zone 6?
Transplant tomatoes after your last frost date once nights stay above 50 degrees F, which is usually mid to late May. Start seeds indoors six to eight weeks earlier, around mid to late March.
What perennial flowers bloom all summer in zone 6?
Catmint, coreopsis, black-eyed Susan, coneflower, perennial salvia and reblooming daylilies give the longest color, especially when deadheaded. Combining early, mid and late bloomers keeps a border in flower from May to October.
What is the difference between zone 6a and 6b?
Zone 6a averages winter lows of -10 to -5 degrees F, while 6b averages -5 to 0 degrees F. The difference affects borderline plants and shifts frost dates by about one to two weeks.
Can I grow vegetables in winter in zone 6?
With protection, yes. Spinach, kale, mache and some lettuces survive in cold frames or under heavy row covers. Growth nearly stops in December and January but resumes in late February and March.
When should I plant bulbs in zone 6?
Plant spring-flowering bulbs in October, after soil temperatures drop below about 60 degrees F and before the ground freezes. Late September works in 6a; early November is usually still fine in 6b.