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Rock Cress Vs Creeping Phlox [5 Major Differences]

Tiny flowers of Rock Cress that come in different shades might deceive you for Creeping Phlox. But it’s essential to know the difference, Rock Cress vs Creeping Phlox.

Generally, Creeping Phlox is a Polemoniaceae, while Rock Cress (Arabis spp) is a member of the mustard family Brassicaceae having different features. Besides, both plants have unalike leaf structures, growing habits, and thriving conditions.

So, follow along to find the key difference between Rock Cress and Creeping Phlox.

Are Rock Cress And Creeping Phlox The Same?

Given the different family and botanical classifications, Ross Cress (Arabis spp) is not the same as Creeping Phlox (Phlox stolonifera).

But both plants have many common attributes, the first being their bloom color.

Generally, the white, pink, lavender, or purple shade on flowers is mutual in both plants, making them appear identical.

They add a pop of color to your garden. So they are often grown to attract pollinators like bees and butterflies.

Further, the other similarity is the low-growing habit of the plant. Rock Cress and Creeping Phlox stay close to the ground. So they are often used as ground cover to create a carpet-like effect.

Moreover, both plants have the potential to persist for more than a single growing season, owing to their perennial nature.

Rock Cress Vs Creeping Phlox: Major Difference

At first glance, it is common to mistake Rock Cress for Creeping Phlox, given their almost similar appearance, like how most confuse Dame Rockest and Phlox.

But with a closer look, you can decode the difference in leaf structure, flower, and growing habits between these biologically dissimilar plants.

1. Origin and Family

The major and only invisible difference between the Rock Cress and Creeping Phlox is their botanical classification and native region.

Rock Cress is a member of the mustard family, Brassicaceae. So, scientifically these Southern European and Asian native plants are the distant cousin of Wild mustard.

Meanwhile, Creeping Phlox, native to Eastern America, belongs to the Polemoniaceae.

2. Growth Habits and Spread

Despite both being low-growing perennials, Rock Cress and Creeping Phlox differ in compactness, with one being a little bushier than the other.

Generally, Rock Cress has a compact mound of foliage, typically reaching a height of 6 to 12 inches. But Creeping Phlox doesn’t normally makeup to the height of Rock Cress, with an average height of 4 to 6 inches.

Although the Rock Cress makes it appear upright, Creeping Phlox is relatively more Creeping like its name.

It can spread up to 2 feet and form a dense mat of foliage in the garden.

On the other hand, Rock Cress has a clumping growth habit, so extending about 1 to 1.5 feet in its immediate surrounding takes time.

3. Foliage Morphology

Rock Cress has narrow, elongated leaves with lobed margins. The leaves are grey to bluish-green with a silvery dust appearance.

As for the Creeping Phlox, it has bright green needle-like leaves that are arranged in an alternate pattern along the stems.

But the actual difference is when you feel the plant. If the leaves feel smooth, soft, and fleshy, it is the Creeping Phlox. But the one with a fuzzy texture with tiny hairs on the surface is the Rock Cress.

4. Flower Appearance

Another distinction between Rock Cress vs Creeping Phlox is petal arrangement and flower size.

Creeping Phlox flaunts its five-petal flowers, usually in the spring. The flowers are relatively larger, 0.75 to 1.5 inches in diameter, with elongated petals often forming a star-like shape.

A side by side comparison of creeping phlox and rock cress.
Only a closer look will help you notice the floral difference.

Unlike the above, Rock Cress has four petals, usually rounded or oval-shaped. The petals gather at the base to form a tube-like structure.

From afar, the blooming Rock Cress resembles a bunch of butterflies covering your garden.

5. Growing Conditions

Rock Cress and Creeping Phlox are drought-tolerant plants capable of surviving hot and dry summers.

However, light tolerance in Creeping Phlox is more than the others.

Generally, Rock Cress thrive in full to partial shade with at least 5-6 hours of direct sunlight. While Creeping Phlox can keep up with some shade, it requires full sun for 7-8 hours.

You can grow the Rock Cress from Zone 3 to Zone 7 without much problem.

But Phlox can barely make it beyond Zone 4 to Zone 9. So, use winter protection like a burlap cover or fleece blanket to protect your plant from winter extremities.

From Editorial Team

Extra Tips!

Neither Creeping Phlox nor the Rock Cress contains harmful chemicals that are toxic to humans and pets.

However, do not allow your pets to nibble on them, as excess greens may lead to gastrointestinal discomfort. Also, the symptoms may elevate to vomiting and weakness.

So, we recommend you contact a nearby vet in case of any mishaps.