Is Garden phlox good for the Colorado Front Range?

Yes, Garden phlox is a well-suited perennial for Colorado's Front Range.

How far apart do I plant Garden phlox?

Space Garden phlox about 17 in apart for a faster, fuller bed, or up to 24 in apart for a looser planting.

Is Garden phlox hardy on the Front Range?

Garden phlox is hardy in USDA 4 to 8. The Colorado Front Range spans roughly USDA 4b to 6a, so it is well within range.

How much water does Garden phlox need?

It needs medium water once established.

Is Garden phlox safe for dogs?

Garden phlox is not known to be toxic to dogs, but confirm with your vet for a specific animal.

Is Garden phlox prone to pests or disease on the Front Range?

Garden phlox can be affected by powdery mildew and other issues common to this group on the Front Range. These are general tendencies, not a diagnosis, many are stress-driven and preventable with good siting and watering. For a specific plant or an active problem, consult a certified arborist or CSU Extension.

How long does Garden phlox bloom?

Garden phlox blooms for several weeks, a long-season performer on the Front Range. Bloom timing shifts a week or two with elevation and spring weather.

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Garden phlox

Phlox paniculata 'Delilah'

Compiled by Nicholas Julia · Reviewed against CSU Extension & Plant Select® · Updated 2026-10-14

Garden phlox (Phlox paniculata 'Delilah') is a perennial suited to the Colorado Front Range. It matures to about 24 to 32 in tall and 18 to 24 in wide, needs medium water, and prefers full sun to partial shade. A richly colored garden phlox in magenta-purple, fragrant and a magnet for butterflies from midsummer on. Wants regular water and good air circulation (mildew-prone in dry heat). Seen at Denver Botanic Gardens.

Not on an authoritative Colorado list. Garden phlox grows on the Front Range, but it is not on the CSU Extension, Plant Select, or Colorado Native Plant Society lists our recommended plants come from. We include it for coverage because people grow it here and ask about it. Read the guidance below as our own honest take, not a formal recommendation.

medium water24 to 32 in tall and 18 to 24 in widePet-safe (non-toxic to dogs)

At a glance

Will it survive here?

Hardiness zones: USDA 4 to 8
Water needs: medium water
Sun: Best in full sun; tolerates partial shade.
Soil: clay, loam, sandy
Soil pH: 6.0 to 7.5
Hail tolerance: moderate
Wind tolerance: moderate
Salt tolerance: low

How big, what shape?

Mature size: 24 to 32 in tall and 18 to 24 in wide
Planting spacing: ~17 to 24 in apart

What it looks like, and when

Bloom time: mid summer, late summer, early fall
Bloom color: purple, pink
Bloom length: Long (several weeks)
Foliage: Deciduous

Who else benefits

Pollinator value: high
Deer: Not rated
Colorado native: No

Also worth knowing

Fire rating: Not rated

Common problems on the Front Range

Powdery mildew
Spider mites

These are general tendencies for this group of plants on the Front Range, not a diagnosis. Many are stress-driven and preventable with good siting and watering. For a specific plant or an active problem, consult a certified arborist or your local CSU Extension office.

Planting & establishment

Give it steady moisture and good air flow; drought stress and crowding invite powdery mildew.

Frequently asked questions

Is Garden phlox good for the Colorado Front Range?: Yes, Garden phlox is a well-suited perennial for Colorado's Front Range.
How big does Garden phlox get?: It matures to about 24 to 32 in tall and 18 to 24 in wide.
How far apart do I plant Garden phlox?: Space Garden phlox about 17 in apart for a faster, fuller bed, or up to 24 in apart for a looser planting.
Is Garden phlox hardy on the Front Range?: Garden phlox is hardy in USDA 4 to 8. The Colorado Front Range spans roughly USDA 4b to 6a, so it is well within range.
How much water does Garden phlox need?: It needs medium water once established.
Is Garden phlox safe for dogs?: Garden phlox is not known to be toxic to dogs, but confirm with your vet for a specific animal.
Is Garden phlox prone to pests or disease on the Front Range?: Garden phlox can be affected by powdery mildew and other issues common to this group on the Front Range. These are general tendencies, not a diagnosis, many are stress-driven and preventable with good siting and watering. For a specific plant or an active problem, consult a certified arborist or CSU Extension.
How long does Garden phlox bloom?: Garden phlox blooms for several weeks, a long-season performer on the Front Range. Bloom timing shifts a week or two with elevation and spring weather.