📆what zone 8b actually means for planting (not just the map color)

translating the zone number into actual dates for my own yard, because "zone 8b" told me nothing useful for the first two years.

winter lows average 15-20°F. that's the entire definition, not some vague "mild" label.

last frost

March 29 here, per OSU's 30-year average. half the years it's the first week of March, half it's mid-April. don't trust a single date.

first frost: mid-to-late October downtown, earlier out in Forest Grove and Canby

growing season: ~295 days counting both frost dates

start tomatoes/peppers indoors

6-8 weeks before last frost, so mid-to-late January under lights, not on a windowsill.

direct sow spinach, arugula, lettuce

mid-January through March 1, then again mid-September through November 1

transplant tomatoes outside

wait til soil's actually warm, not just past the frost date. I go first week of May and still lose one to slugs some years

harden off

a week, not a weekend. I skipped this year one and lost half a flat overnight (learned the hard way).

fall bulbs (tulips, daffodils): plant in October, before the ground gets saturated

last realistic frost for tender annuals

mid-April if you actually want to skip the gamble, not the printed calendar date

microclimate

the zone map is an average, not a promise. my south fence bed runs basically 9a, the low spot by the gate floods and acts like 8a

USDA map update: revised in 2023, some of Portland edged from 8a into 8b

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