How to Grow Blue Lobelia

Lobelia siphilitica · Zones Data not available

Blue Lobelia is a perennial grown for its blooms, which open in summer and return year after year. Notably, it shrugs off deer. Its summer flowers are a real draw for native bees, butterflies, and hummingbirds.

Zones

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pH Range

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USDA PLANTS DatabaseUSDA PHZM 2023ASPCA

What Blue Lobelia is

Blue Lobelia grows as a perennial and reaches around three feet at maturity. It blooms in summer. It's also deer-resistant.

How to grow Blue Lobelia

USDA Zones

Data not available

USDA PHZM 2023

Soil pH

Data pending

USDA PLANTS Database

Sun

Data pending

plant_species_v5.csv

Drainage

Data pending

plant_species_v5.csv

Mature Height

3 ft

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Frost-Free Days

0+

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  1. Start the season right

    Plant blue lobelia in full sun, once the soil has warmed and frost risk has passed.

  2. Match the soil

    Pull a soil test from your local Extension lab to confirm pH and drainage match blue lobelia's needs before planting.

  3. Water steadily

    Keep the root zone evenly moist through establishment. Match watering to the plant's drainage preference and your local rainfall.

  4. Harvest at its peak

    Cut blue lobelia blooms in the cool of the morning, just as they open, for the longest display.

Good to know

One caution for pet owners — blue 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.)

Blue Lobelia is a standout pollinator plant — high value to bees and other pollinators. (Source: Xerces Society, Pollinator Partnership.)

Where Blue Lobelia thrives

Whether blue lobelia thrives on a given site comes down to its soil pH, drainage, sun, and frost dates — the conditions that vary parcel to parcel.

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See if Blue Lobelia will thrive on your land

Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether blue lobelia actually takes — we score it against the real conditions at your address.

Three things about your exact spot that zone averages miss:

Your soil pHYour frost-free daysYour sun & shade

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Frequently Asked Questions

Can I grow Blue Lobelia in my zone?

Zone data for blue lobelia is being finalized. A Growable Ground report checks your parcel's full suitability against federal soil, climate, and zone data.

When should you plant Blue Lobelia?

Most growers plant blue lobelia after the last spring frost, once the soil has warmed. Your local frost dates set the exact window — a Growable Ground report reads them for your address.

What soil does Blue Lobelia need?

Specific pH data for blue lobelia is pending. A soil test from your local Extension lab confirms what your site needs.

Does Blue Lobelia attract pollinators?

Yes — blue lobelia's flowers are a strong nectar and pollen source for native bees, butterflies, and hummingbirds (Xerces Society, Pollinator Partnership).

Is Blue Lobelia safe for pets?

Blue 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.