cardinal flower (Lobelia cardinalis), photographi

How to Grow Cardinal Flower

Lobelia cardinalis · Zones 3-9

Cardinal Flower is a perennial grown for its blooms, which open in summer and return year after year. It's hardy across USDA zones 3 through 9 and shrugs off deer. Its summer flowers are a real draw for hummingbirds, native bees, and butterflies.

Cardinal Flower — the short answer

Cardinal Flower: grown in zones 3–9.

USDA zones
3–9
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

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.

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Zone averages can't see the slope, soil, frost, and sun that decide whether cardinal flower actually takes — and those shift from one yard to the next. Enter your address and we'll score cardinal flower against your land's real conditions.

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What Cardinal Flower is

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

How to grow Cardinal Flower

Cardinal Flower grows in USDA zones 3 through 9.

USDA Zones

3-9

USDA PHZM 2023

Soil pH

Data pending

Sun

Data pending

Growable Ground plant catalog

Drainage

Data pending

Growable Ground plant catalog

Mature Height

3 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

  1. Start the season right

    Plant cardinal flower in full sun.

  2. Match the soil

    Pull a soil test from your local Extension lab to confirm pH and drainage match cardinal flower'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 cardinal flower blooms in the cool of the morning, just as they open, for the longest display.

Where Cardinal Flower thrives

Cardinal Flower is hardy across USDA zones 3 through 9. 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 39 spans average winter lows from -40°F to 30°F (USDA PHZM 2023). Across the 50 states and DC, that band covers 42 outright and splits 9 more down the middle — and which side of that line your land sits on changes the answer.

Zones 3–9 highlighted on the USDA national hardiness zone map

Zones 3–9·Where Cardinal Flower growsOpen map →

Where Cardinal Flower stands, state by state

Cardinal Flower is rated for zones 39 — a cold floor USDA puts at -40 to -30°F. Across the 50 states and DC, 42 sit fully inside that band, the line runs through 9 more, and 0 sit outside it — and inside every split state, the same line runs on at county grain.

Fully inside zones 3–9

42 states

3 of 42 shown

The line runs through

9 states

3 of 9 shown

Cardinal Flower’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 Cardinal Flower

In rotation planning, cardinal flower 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)

Good to know

One caution for pet owners — cardinal flower 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.)

Cardinal Flower is a standout pollinator plant — high value to bees and other pollinators. (Source: Lady Bird Johnson Wildflower Center.)

Your land is one point inside Cardinal Flower'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.

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See if Cardinal Flower will thrive on your land

Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether cardinal flower 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

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 Cardinal Flower

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 DatabaseUSDA PHZMASPCA

Frequently asked questions

Can I grow Cardinal Flower in my zone?

Cardinal Flower grows in USDA hardiness zones 3 through 9 (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 Cardinal Flower?

Time cardinal flower to your own season rather than the calendar. Your local frost dates set the exact window — a Growable Ground report reads them for your address.

What soil does Cardinal Flower need?

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

Does Cardinal Flower attract pollinators?

Yes — cardinal flower's flowers are a strong nectar and pollen source for hummingbirds, native bees, and butterflies. (Source: Lady Bird Johnson Wildflower Center.)

Is Cardinal Flower safe for pets?

Cardinal Flower 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.)