Lobelia is an annual or perennial grown for its blooms, which open from spring through fall and return year after year. It's hardy across USDA zones 10 through 11, shrugs off deer and grows just as well in a container as in the ground. Its flowers are a moderate draw for honeybees, native bees, and butterflies.
Lobelia — the short answer
Lobelia: grown in zones 10–11, part sun, pH 5.5–7, about 90 days to maturity.
- USDA zones
- 10–11
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Soil pH
- 5.5–7
- Growable Ground Plant Database
- Sun
- Part Sun
- Growable Ground Plant Database
- Days to Maturity
- 90 days
- Growable Ground Plant Database
- Frost-kill temp (growing season)
- 28°F
- Growable Ground Plant Database
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — each tile names its own row's source, because per-field provenance varies.
Score Lobelia on your exact land.
Zone averages can't see the slope, soil, frost, and sun that decide whether lobelia actually takes — and those shift from one yard to the next. Enter your address and we'll score lobelia against your land's real conditions.
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What Lobelia is
Lobelia grows as an annual or perennial and reaches around 6 inches at maturity. It blooms from spring through fall. It's also deer-resistant and well suited to containers.
How to grow Lobelia
Lobelia grows in USDA zones 10 through 11. Lobelia does best in part sun — at least 4 hours of direct sun a day — and soil from pH 5.5 to 7, on well-drained ground. It needs around 700 growing degree days to mature, which is why climate matters as much as soil.
USDA Zones
10-11
USDA PHZM 2023
Soil pH
5.5 - 7
Growable Ground Plant Database
Sun
Part Sun
Growable Ground plant catalog
Drainage
well (dry spells)
Growable Ground plant catalog
Frost Kill Temperature
28°F
Where cold starts killing growing tissue. Not a winter-survival floor — a dormant perennial takes far colder, which its hardiness zone answers.
Growable Ground Plant Database
Days to Maturity
90 days
Growable Ground plant catalog
GDD Required
700+
Growing degree-days of accumulated warmth it needs to mature — humid summers reach this faster than cool coastal ones.
Growable Ground plant catalog
Mature Height
0.5 ft
Growable Ground plant catalog
Frost-Free Days
0+
The frost-free stretch it needs start to finish — short-season areas may need an indoor head start.
Growable Ground plant catalog
Start the season right
Plant lobelia in part sun with at least 4 hours of direct sun. It grows in the cool halves of the year, so sow it in spring or late summer rather than waiting for midsummer heat.
Match the soil
Lobelia prefers pH 5.5 to 7 (Growable Ground Plant Database). A quick soil test from your local Extension lab tells you whether to add lime or sulfur to land in band.
Water steadily
Keep the root zone evenly moist through establishment. A 2–3 inch mulch layer holds moisture without waterlogging.
Harvest at its peak
Cut lobelia blooms in the cool of the morning, just as they open, for the longest display.
Where Lobelia thrives
Lobelia is hardy across USDA zones 10 through 11. Zone is only the starting point, though: the soil pH, drainage, and frost dates on your specific land decide how well it actually does.
A USDA zone is a 10°F band of average annual extreme winter minimum, so zones 10–11 spans average winter lows from 30°F to 50°F (USDA PHZM 2023). Across the 50 states and DC, that band covers none outright but splits 8 down the middle — and which side of that line your land sits on changes the answer.
Zones 10–11·Where Lobelia growsOpen map →
This map is derived from the USDA ARS / PRISM Plant Hardiness Zone Map (2023) and is not the official USDA Plant Hardiness Zone Map.
Where Lobelia stands, state by state
Lobelia is rated for zones 10–11 — a cold floor USDA puts at 30 to 40°F. Across the 50 states and DC, 0 sit fully inside that band, the line runs through 8 more, and 43 sit outside it — and inside every split state, the same line runs on at county grain.
The line runs through
8 states
- California · zones 4b-11a
- Nevada · zones 4a-10a
- Arizona · zones 5b-10b
3 of 8 shown
Lobelia’s band covers part of each of these states — which side of the line your county sits on changes the answer, and each state page draws it.
State zone extents: USDA Plant Hardiness Zone Map (PHZM) 2023. A zone is a 10°F band of average annual extreme minimum temperature, so a state that splits the band contains the boundary — its own page draws the county line, and a parcel report resolves which side your land sits on.
What grows around Lobelia
Growing guides for lobelia
In rotation planning, lobelia counts as a Other — beds recover best when other crops don’t follow each other in the same spot year over year. (Growable Ground derivation — crop-rotation group from botanical family)
Related plants in annual flower
Good to know
One caution for pet owners — lobelia is toxic to dogs and cats (moderate severity). Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency. (Source: ASPCA.)
Lobelia offers moderate value to bees and other pollinators. (Source: Pollinator Partnership.)
Your land is one point inside Lobelia's range
This page resolves to the species. Your state page draws the county line, and a report reads the parcel — the soil pH, drainage, sun, and frost dates on your exact ground, which no species average can see.
See if Lobelia will thrive on your land
Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether lobelia actually takes — we score it against the real conditions at your address.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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How we know this about Lobelia
The figures above are cited per row, not per site: the pH band names this plant’s own source column, the three temperature figures each carry their own, and days-to-maturity cites the publication that actually lists it. All of it comes from the Growable Ground Plant Database — a compilation over FAO ECOCROP, USDA PLANTS, and university Extension sources, published openly with per-field provenance.
Grounded inUSDA PLANTS Database•USDA PHZM•ASPCA
Frequently asked questions
Can I grow Lobelia in my zone?
Lobelia grows in USDA hardiness zones 10 through 11 (USDA PHZM 2023). Zone is one factor — soil pH, drainage, and frost dates on your specific parcel also shape whether it takes.
When should you plant Lobelia?
Lobelia is a cool-season crop, so it goes in during the cool halves of the year — early spring, and again in late summer for a fall planting — rather than at the height of summer heat. Your local frost dates set the exact window — a Growable Ground report reads them for your address.
How much sun does Lobelia need?
Lobelia does well in partial sun — around 4 hours of direct sun, and it takes some afternoon shade in stride. That flexibility makes it a good match for a bed the house or a nearby tree shades for part of the day. A Growable Ground report maps how the sun actually falls on your land, hour by hour, so you can set it where the light lines up.
What soil does Lobelia need?
Lobelia prefers soil pH 5.5 to 7, on well-drained ground (Growable Ground Plant Database). Your report scores your parcel's actual soil against that using USDA SSURGO data.
Does Lobelia attract pollinators?
Yes — lobelia's flowers are a solid nectar source for honeybees, native bees, and butterflies. (Source: Pollinator Partnership.)
Is Lobelia safe for pets?
Lobelia is toxic to pets (dogs,cats) with moderate severity. Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency. (Source: ASPCA.)