My Borders Stay Weed-Free All Summer Thanks to This One Plant – and its Fragrance is as Fabulous as its Flowers

If you’re tired of weeding your backyard borders already, creeping phlox is the weed-supressing saviour you’ve been waiting for. Moss phlox grows into a low, lush carpet of needle-like foliage just four inches high, dense enough to block weeds yet still lets bulbs push through. It happily co-exists with bigger perennials and shrubs, and brings drifts of pretty flowers all through April and May that are a nectar-rich treat for early bees and butterflies. While Phlox subulata spreads pretty quickly, it’s not invasive and, thanks to its very shallow roots, is simple to pull up if it ever wanders where it’s not supposed to.

A polite, faff-free groundcover that brings flowers as it banishes weeds? Yes please!

I added creeping phlox to two big borders in my front yard a couple of years ago as groundcover to suppress weeds, largely because I hate doing garden chores where all the world can see me. I soon discovered that it was super-easy to split moss phlox to get new plants for free. So my mat of moss-like foliage quickly grew, creeping around all the other plants in the border so weeds don’t even get a look-in. Problem sorted!

Moss phlox is a perennial so this border is now going to stay pretty much weed-free forever more. It's evergreen in milder climates and, even though leaf-tips may brown in colder zones 3–5, the foliage is typically retained through winter to give year-round groundcover.

Purple Varieties

Pros & Cons of Creeping Phlox

Moss phlox flowers have a sweet, honey-like scent that’s strongest at dusk to attract pollinating moths. It tolerates light foot traffic so won’t complain when you need to access plants for pruning and, once established, is drought-tolerant. It’s cold-hardy and heat-tolerant, too, so most varieties are suitable for zones 3–9.

What’s the ‘but’ I hear you ask?! There is one teeny-tiny issue, and I’ll get to that! But rest assured that because creeping phlox spreads by growing leafy, above-ground stems that root into the soil when they make contact, there’s no worrying about rhizomes running riot underground where you can’t see them. Each plant grows into a mat that’s around 18–24 inches wide, and the trick to ensuring their spread is an amiable amble that leaves plenty of space for neighboring perennials to grow is to keep to this planting distance and be patient for a year or two while the gaps are slowly filled.

This spreading habit means that creeping phlox will spill over a pathway and tumble down the face of a raised bed or wall, too.

But yes, let's get to that ‘but’! When the leaves are crushed underfoot, they can release a musky aroma that some liken to the smell of cannabis. No judgement here, but best to know!

Pink Varieties

Where to Grow Creeping Phlox

Creeping phlox grows best in a sunny spot which gets at least six hours of sunlight a day. It will tolerate partial shade but won’t flower as well or grow such dense, weed-suppressing foliage. Phlox subulata also needs good drainage to thrive so, if your border soil sits wet over winter, this bijou beauty isn't the best solution for you.

Give moss phlox the conditions it loves and, other than watering for the first year while it establishes, the only care needed is to trim off the faded flowers and foliage tips once it's finished blooming. Aim to reduce the mat's height by half to keep the growth dense enough to suppress weeds, which is quick and easy to do with a pair of hedge shears like these from Amazon. If any bare patches develop, simply trim around the gap to stimulate new stems to grow.

Red & White Varieties

How to Make Your Money Go Further

If you buy creeping phlox plants in spring for groundcover, bear in mind that it can be more cost-effective to buy a larger plant and split it into several smaller plants, than it is to buy multiple less mature plants.

Dividing moss phlox is simple to do. Choose a mature plant in a larger pot size and water it thoroughly the day before you plan to divide it. Then ease it out of its pot and, depending on the size of the plant, use your hands to gently split it in half, and in half again if it's large enough, so you have 2 or 4 sections. It's important that each section has a good amount of roots, and it's fine to use a bread knife to help create the sections if the rootball is very dense. Plant each section immediately, water well, and water during dry spells until roots are well established.

You can divide established plants growing in the ground just as easily. So easily, in fact, that I don’t even bother digging the whole plant up now: I simply slice off half the plant with a spade while it's still in the ground, dig up a half and divide that into chunks to replant, and leave the other half to carry on growing where it is. It is important to water the half that's left in the ground, as well as the newly planted sections, to settle soil around the roots and reduce shock.

If you can't decide which variety of moss phlox to grow, then different cultivars will happily intermingle for a tapestry of flowers.