One of the best tools that you have as a gardener to help figure out your gardening schedule is the USDA zone info. The zone information's most crucial data reveals the average last frost and the lowest expected temperature for your area.
To determine the appropriate planting time for cosmos, you can utilize the USDA zone information for the 3b region.
Planting Calendar for Cosmos
| Frost tolerance for cosmos | Tolerant of some frost |
| When to plant | Up to 5 weeks before last frost |
Because cosmos are slightly tolerant to cold, you can plant them earlier in the year compared to other frost-sensitive plants.
Visual Calendar for Cosmos
Planting Calendar for Cosmos in Zone 3b
Key dates to remember:
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Start seeds indoors: | Feb 15 |
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Direct sow seeds: | Apr 15 |
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Transplant starts outside: | May 1 |
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Summer harvest time: | Jun 1 |
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Start winter crop: | Jun 15 |
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Start over-winter: | Sep 15 |
Last Frost Date for Zone 3b
The average date of last frost is May 15 in zone 3b. It might get as low as -35°F (-37°C) during the coldest months of winter.
As the USDA zone information for zone 3b is only an average, the actual date of your last frost will differ annually. Since every microclimate is different, you should also watch the weather forecast closely as you get close to planting time. Watch the weather forecast before planting outside, and have frost protection ready if low temperatures are expected.
USDA Info for Zone 3b
Here is the info for USDA zone 3b.
| Average Date of Last Frost (spring) | May 15 |
| Average Date of First Frost (fall) | 2015-09-15 |
| Lowest Expected Low | -35°F (-37°C) |
| Highest Expected Low | -30°F (-34°C) |
This means that on a really cold year, the coldest it will get is -35°F (-37°C). On most years you should be prepared to experience lows near -30°F (-34°C).
Other Plants to Grow in Zone 3b
You may be interested in our other planting guides for zone 3b.
Vegetables in Zone 3b
- Amaranth
- Artichokes
- Arugula
- Asparagus
- Beans
- Beets
- Bok Choy
- Broccoli
- Brussels Sprouts
- Cabbage
- Cantaloupe
- Carrots
- Cauliflower
- Celery
- Chervil
- Collard Greens
- Corn
- Cornsalad
- Cucumbers
- Eggplant
- Garlic
- Ginger
- Green Onions
- Honeydew Melons
- Kale
- Kohlrabi
- Leeks
- Lettuce
- Melons
- Okra
- Onions
- Parsnips
- Peas
- Peppers
- Potatoes
- Pumpkins
- Radicchio
- Radishes
- Rhubarb
- Rutabaga
- Shallots
- Spinach
- Strawberries
- Summer Squash
- Sweet Potatoes
- Swiss Chard
- Tomatilloes
- Tomatoes
- Turnips
- Watercress
- Watermelon
- Winter Squash
- Zucchini
Herbs in Zone 3b
Flowers in Zone 3b
- Alyssum
- Amaranth
- Anemones
- Asters
- Bachelors Buttons
- Begonias
- Bells of Ireland
- Black-eyed Susans
- Bleeding Hearts
- Calendula
- Carnations
- Chinese Lanterns
- Chrysanthemums
- Clematis
- Coleus
- Columbine
- Coneflowers
- Coreopsis
- Cornflowers
- Cosmos
- Crocus
- Daffodils
- Dahlia
- Daisies
- Daylilies
- Delphiniums
- Dianthus
- Dusty Miller
- Echinacea
- Foxgloves
- Geraniums
- Hellebores
- Heuchera
- Hibiscus
- Hollyhocks
- Hostas
- Hydrangeas
- Impatiens
- Iris
- Lantana
- Lilies
- Lobelia
- Love-in-a-mist
- Lupine
- Marigolds
- Morning Glories
- Nasturtiums
- Pansies
- Peonies
- Petunias
- Phlox
- Poppies
- Portulaca
- Primrose
- Red Hot Pokers
- Roses
- Rudbeckia
- Salvia
- Shasta Daisies
- Snapdragons
- Statice
- Stocks
- Strawflowers
- Sunflowers
- Sweet Peas
- Tulips
- Verbena
- Vinca
- Violets
- Wisteria
- Yarrow
- Zinnias
USDA Zones
USDA zones are a popular way of determining which plants can grow in your area. Zones tell you when your average first and last frost date are, as well as how cold you can expect it to get in the winter.
Our site works best if you choose your zone from the list below. If you do not know your USDA zone, then you can use our zone map.
