Phlox subulata aka Moss Phlox

Phlox subulata is a low-growing, mat-forming ground cover that typically reaches only 4-6 inches (10-15 cm) in height but spreads vigorously to 2-3 feet (60-90 cm) wide. The plant grows at a moderate pace, taking 2-5 years to reach mature size. Its prostrate, creeping habit makes it ideal for covering slopes, filling in rock gardens, and creating colorful carpets of blooms.

Phlox subulata is native to the eastern and central United States and Canada. Its natural range extends from the Appalachian Mountains through the northeastern and midwestern states. In the wild, it grows in rocky and sandy barrens, savannas, rocky ledges, slopes, clearings, and open woodlands. The species has been introduced to parts of Europe including Austria, Germany, and the Czech Republic.

Phlox subulata produces masses of star-shaped, five-petaled flowers from March to May, with peak bloom in April-May. Each flower is about ¾ inch (2 cm) across with a tubular base and notched petals. Flowers come in a range of colors including pink, lavender, purple, blue, red, and white. The blooming period lasts 3-4 weeks, creating a spectacular carpet-like display that can completely cover the foliage.

Phlox subulata flowers have a sweet, floral fragrance with slightly spicy notes. The scent comes from terpenes in the blooms. Interestingly, the odor has sometimes been compared to marijuana due to similar chemical compounds. Fragrance intensity varies between cultivars—some varieties like 'Fort Hill' have a noticeable sweet scent, while others are less fragrant.

Many cultivars of Phlox subulata are available in various colors. 'Candy Stripe' features pink-and-white striped petals. 'Emerald Blue' produces lilac-blue flowers. 'Fort Hill' has deep pink blooms with dark eyes and good disease resistance. 'Amazing Grace' offers white flowers with pink eyes. Other notable varieties include 'Red Wings' (crimson red), 'White Delight' (pure white with southern blight resistance), and 'Purple Beauty' (rich purple).

Phlox subulata is an outdoor plant that thrives year-round in USDA zones 3-9 and UK hardiness zone H6. It can withstand temperatures down to -20°C (-4°F), making it suitable for most temperate climates. The evergreen to semi-evergreen foliage persists through winter, providing year-round interest. It's ideal for rock gardens, slopes, borders, and as ground cover where it helps prevent erosion.

Phlox subulata can be propagated through division, cuttings, or seeds. For cuttings, take softwood cuttings from non-flowering shoots in spring or early summer, dip in rooting hormone, and root in a propagator with warmth and humidity. Root cuttings can also be taken in early autumn or winter.

Cut back Phlox subulata stems by half after flowering to maintain a compact shape and promote denser growth. This post-bloom pruning can also stimulate a light rebloom later in the season. In late summer or early autumn, trim any straggly or untidy growth. Regular pruning helps prevent the center of the plant from becoming bare and woody over time.

Phlox subulata is notably resistant to powdery mildew, unlike many other phlox species. However, spider mites can be problematic in hot, dry conditions, and foliar nematodes may cause damage in wet, humid environments. Stem and bulb eelworm can cause twisted, yellowing leaves—there's no cure, so infected plants must be removed. Phytophthora root rot and southern blight occasionally occur; choose resistant cultivars like 'Fort Hill' in problem areas.

Phlox subulata flowers attract a variety of pollinators including butterflies, bees, moths, and hummingbirds. The tubular flowers are particularly appealing to long-tongued insects like swallowtail butterflies, sphinx moths, and clearwing moths. As an early spring bloomer, it provides crucial nectar for emerging butterflies like mourning cloaks, eastern commas, and spring azures. Bees collect both pollen and nectar from the flowers.

Phlox subulata is extremely cold-hardy, tolerating temperatures down to -20°C (-4°F) or even colder in USDA zone 3. It thrives in typical temperate conditions and maintains its evergreen or semi-evergreen foliage through winter. In hot, humid summers, the plant appreciates some afternoon shade to prevent stress. It's well-adapted to exposed and sheltered sites alike.

In spring, watch for new growth and enjoy the spectacular bloom display. After flowering ends in late spring, cut back stems by half to encourage dense regrowth and possibly a light rebloom. Summer requires minimal care for established plants—water only during extended drought. In autumn, trim straggly growth and apply a light mulch in colder areas. Winter needs are minimal as the evergreen foliage persists; avoid overwatering in wet winter conditions.

Moss Phlox is a low-maintenance plant that requires minimal attention, making it an excellent choice for beginners.

Moss Phlox should be watered regularly, allowing the soil to dry out between waterings.

Moss Phlox loves a well-draining soil. Perlite and vermiculite help with drainage, while coco coir adds organic matter, so a good potting soil mix will have all three. You can improve store-bought soil by adding some perlite to it.

Moss Phlox requires abundant, bright and direct light. Placing it less than one foot from a window is the best way to make sure the plant receives enough light to survive and thrive. Depending on your region, however, the current weather can affect the placement of the plant in your home. For example, in some areas the sun may be too direct and intense, so it's best to place it farther away from the window. You may also need to adjust your placement according to the season as the sunlight can change intensity over the course of the year. If you live in a region with significant temperature fluctuations, such as a desert, you may need to place the plant a bit farther away from the window to avoid extreme heat or cold. With some care and attention, your Moss Phlox will be sure to bring you many years of beauty and enjoyment.

The Moss Phlox should be transferred to a new pot once it has increased in size two-fold, or on an annual basis, whichever occurs earlier. Replacing the soil with fresh potting soil containing all the necessary nutrients, is sufficient enough to support the growth of the plant, thus avoiding the need to use fertilizer. It's important to note that plants derive their energy from the sun and not fertilizer.

Moss Phlox is not known to cause harm to humans or pets.