Yes — Strong Match
sweet autumn clematis (zones 5-9) fits entirely within California's zone range (5a-11a).
Zone Comparison
Sweet Autumn Clematis Needs
- USDA Zones: 5-9
- Soil pH: 5.5 - 7.5
- Sun: Full Sun
- Drainage: well (dry spells)
- Frost-Free Days: 150+
California Has
- USDA Zones: 5a-11a
- Last Frost: Jan 15 - May 15
- First Frost: Oct 1 - Dec 31
- Annual Rainfall: 5-80 inches
- Common Soils: Alluvial clay, Sandy loam, Adobe clay
Plant Zone Range (zones 5-9)
Preferred Soil pH
Plant data: USDA PLANTS Database / plant_species_v5.csv. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
Growing Season Fit
Zone compatibility says you can survive winter here. Whether the growing season is long enough — and warm enough — is a different question.
Frost-free days
Sweet Autumn Clematis wants 150+ frost-free days; a typical California site sees ~220 (NOAA Climate Normals). That leaves comfortable headroom for succession planting.
Growing degree days
Sweet Autumn Clematis needs ~2000 GDD (base 50°F) to ripen. The state median runs ~3850 GDD (USDA NRCS county aggregates), so California's typical season clears that easily.
Climate aggregates derive from USDA NRCS county-level hardiness data + Cornell CALS Extension GDD-by-region tables + MSU Extension chill-hours-by-zone (1991-2020 NOAA Climate Normals baseline).
Soil + Drainage Fit
Sweet Autumn Clematis likes near-neutral soil (pH 5.5-7.5). That's the common-ground band across California's alluvial clay and sandy loam — a soil test confirms it for your site. Drainage matters: this plant wants well (dry spells). If your California site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH and drainage requirements from USDA PLANTS Database. California soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Sweet Autumn Clematis in California — Quick Answer
- Verdict: Yes — Strong Match
- Plant Zones: 5-9 (USDA PLANTS Database)
- State Zones: 5a-11a (USDA ARS PHZM 2023)
- Growing Season: Jan 15 - May 15 to Oct 1 - Dec 31 (NOAA Climate Normals)
What Else to Consider
Zone compatibility tells you about winter cold survival — but California growers also need to think about:
Drought is a persistent challenge — irrigation is essential in most regions
Wildfire risk affects rural and foothill properties
Adobe clay soils in valleys drain poorly without amendment
Wide climate variation means plant selection is highly location-specific
Where in California Fits Best
California spans USDA zones 5a-11a — wide enough that one county's microclimate is very different from another's. Three counties carry the closest zone match for sweet autumn clematis:
Pollinator + Wildlife Value
Sweet Autumn Clematis draws pollinators (moderate value, USDA PLANTS Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Deer pressure is meaningful across much of California; sweet autumn clematis is listed as deer-resistant (USDA PLANTS Database), which makes it a safer pick for unfenced sites.
California Cooperative Extension
For California-specific cultivar recommendations, planting calendars, and pest pressure for sweet autumn clematis, the canonical source is UC Agriculture and Natural Resources. Their fact sheets carry the local trial data we can't generalize across 50 states.
Check your specific parcel in California
State-level data is a sketch. Your Growable Ground report scores sweet autumn clematis against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
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