Union City, California planting calendar and frost dates

Frost dates in Union City

A 32°F night is rare here: it happens in about 45% of years, so median frost dates do not describe a typical year.

NOAA U.S. Climate Normals 1991-2020 for Hayward Air Terminal, 2.1 miles WSW of the city center. Low-lying and rural spots often frost later in spring and earlier in fall than airports and city centers. Union City shares this station with Hayward, so the two cities have the same frost dates and planting calendar.

What to plant each month in Union City

Because frost is rare and light, cool-season crops (brassicas, greens, roots, peas, garlic) are planted from midsummer through early spring and grow through the rainy winter, while many greens and roots can be sown almost any month. Warm-season crops go in April to June after the soil warms; summer is dry, so they need regular irrigation. Fog belts (western San Francisco, Daly City, coastal San Mateo) have cool summers where tomatoes, peppers, eggplant, melons and corn struggle, whereas the sunnier inner-Bay shoreline ripens them more reliably. The months below follow the planting calendar for San Francisco Bay Area & Northern California Coast from the Cooperative Extension sources listed.

1. January

   Plant: asparagus, beets, cilantro, collard greens, garlic, green onions, kale, lettuce, mints, onions, oregano, radishes, rhubarb, roses, sage, swiss chard, thyme

2. February

   Plant: asparagus, beets, broccoli, cabbages, carrots, cauliflower, celery, cilantro, collard greens, daylilies, garlic, green onions, kale, leeks, lettuce, mints, onions, oregano, parsley, peas, potatoes, radishes, rhubarb, sage, swiss chard, thyme, turnips

3. March

   Plant: asparagus, beets, broccoli, cabbages, carrots, cauliflower, celery, cilantro, collard greens, dahlias, gladioli, green onions, kale, leeks, lettuce, mints, onions, oregano, parsley, peas, radishes, rhubarb, sage, spinach, swiss chard, thyme, turnips

4. April

   Plant: basil, beets, cantaloupes, carrots, celery, chives, cilantro, collard greens, cosmos, cucumbers, dahlias, dill, gladioli, green beans, kale, leeks, lettuce, lilies, marigolds, mints, oregano, parsley, peppers, petunias, pumpkins, radishes, sage, snapdragons, spinach, sunflowers, sweet corn, swiss chard, thyme, tomatoes, turnips, winter squash, zucchini

5. May

   Plant: basil, beets, cantaloupes, carrots, cilantro, collard greens, cucumbers, dill, eggplants, green beans, kale, leeks, lettuce, mints, oregano, peppers, potatoes, pumpkins, radishes, sage, sunflowers, sweet corn, swiss chard, thyme, tomatoes, turnips, watermelons, winter squash, zucchini

6. June

   Plant: basil, beets, brussels sprouts, carrots, cilantro, collard greens, cucumbers, dill, green beans, kale, leeks, lettuce, mints, oregano, peppers, pumpkins, radishes, sage, sunflowers, sweet corn, swiss chard, thyme, turnips, watermelons, winter squash, zucchini

7. July

   Plant: beets, broccoli, brussels sprouts, cabbages, carrots, cauliflower, cilantro, collard greens, green beans, kale, leeks, lettuce, mints, oregano, radishes, sage, sweet corn, swiss chard, thyme, turnips

8. August

   Plant: beets, broccoli, brussels sprouts, cabbages, carrots, cauliflower, celery, cilantro, collard greens, green onions, kale, leeks, lettuce, mints, onions, oregano, parsley, potatoes, radishes, sage, spinach, swiss chard, thyme, turnips

9. September

   Plant: beets, broccoli, brussels sprouts, cabbages, cauliflower, celery, cilantro, collard greens, garden mums, green onions, kale, leeks, lettuce, mints, onions, oregano, parsley, peas, poppies, radishes, sage, snapdragons, spinach, swiss chard, thyme, turnips

10. October

    Plant: beets, cilantro, collard greens, garlic, green onions, kale, leeks, lettuce, mints, onions, oregano, parsley, peas, radishes, sage, swiss chard, thyme, turnips

11. November

    Plant: beets, cilantro, collard greens, garlic, green onions, kale, lettuce, mints, onions, oregano, peas, radishes, sage, swiss chard, thyme

12. December

    Plant: beets, cilantro, collard greens, garlic, green onions, kale, lettuce, mints, onions, oregano, radishes, sage, swiss chard, thyme, tulips, wildflowers

Frost dates and zones by ZIP code in Union City

All 2 of Union City's main ZIP codes take their frost dates from Hayward Air Terminal, so the dates on this page apply across the city. The hardiness zone is 10a in 94587, and 9b in 94552.

Hayward Air Terminal also supplies the frost dates for Hayward, so their planting calendars match Union City's.

Nearby cities

• Hayward, CA zone 10a
• Fremont, CA zone 9b
• Pleasanton, CA zone 9b, last frost Feb 15
• Dublin, CA zone 9b, last frost Feb 15
• San Leandro, CA zone 10a, last frost Jan 7
• San Ramon, CA zone 9b, last frost Feb 15