How to Grow Creeping Phlox: The Ultimate Guide
Written by Hannah Miller. Reviewed and Fact Checked by Elizabeth Smith. Published to Spring Plants. Updated: 20th February 2023.
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Creeping phlox is my number one choice for growing next to paths and in rockeries, where it can creep over the surface and delight with its abundance of small blooms.
I had several phlox plants at my previous property and it was a pleasure to grow, easy to maintain and reliable.
Key plant details:
- Spring-flowering: I was rewarded with around three weeks of blooms in May and sometimes into June.
- Ground covering: I feel it’s ideally suited to path edges, around driveways, in rockeries and as a space filler.
- I found that creeping phlox was the perfect weed suppresser.
- Perennial and low maintenance: I never experienced issues with weeds, pests or diseases in my garden.
Size
Height: Up to 15cm (6″)
Spread: Up to 50cm (20″)
Type
Perennial evergreen, sometimes semi-evergreen
Growth
Moderate growth rate. Time to max size: 3-5 years
Difficulty
Easy to grow, even for beginners
Native
Native to North America
Location
Rockeries, paths, around boulders and under tree canopy
Sunlight
The more sunlight, the more flowers you can expect but phlox still performs well in dappled shade
Hardiness
US zone 4-9 and hardy in all parts of the UK
Water & Feed
Drought tolerant once established but requires reliably moist soil until then. Feed twice a year in the spring and again in early summerÂ
Companions
Phlox is versatile: Grow with alliums, tulips, irises, aubrieta, lamb’s ear +many more spring and early summer plants
Planting
Spring or autumn when the soil is warm but avoiding the extremes of a hot summer or cold winter
Flowering
April, May and June
How to Grow Creeping Phlox, Based on My Experience
If you’ve never grown creeping phlox before, here I answer questions that I feel will help you get started and the information I provide is based on my experience:
How is Creeping Phlox Sold?
Creeping phlox can be grown from seed, I tried it once, and the results were mixed and slow going.
Phlox is sold as plugs in most garden centres and I found it can be propagated easily via division and stem cuttings. I started off with a few plug plants a few years ago and quickly grew my stock by division.
Where is the best spot for creeping phlox?
In my previous garden, I found that creeping phlox produced an abundance of blooms when grown in full sun, but the ones I had in partial shade still performed well, not just not quite as prolific.
Based on my experience, I think you should grow them in or near:
- Rockeries.
- Edges of paths and patios.
- Under taller plants and trees where enough light still reaches the ground.
Is creeping phlox full hardy? Will it survive the US/UK winters?
Creeping phlox is winter hardy in all parts of the UK and in US zones 4-9, and I never had any issues with the cold weather, it always bounced back from winter.
Creeping phlox is a perennial and in my garden in Surrey it was evergreen but I’ve seen some that were deciduous in cooler parts of the country.
Is creeping phlox invasive?
While creeping phlox isn’t invasive, I’ve seen some gardeners confuse it with a similar plant that very much is.
The petals on Dame’s Rocket look remarkably similar to those on phlox, but this species is invasive and self-seeds easily and quickly, so much so that some countries and US states have placed restrictions on it.
What soil conditions are best for creeping phlox?
I’ve always grown creeping phlox in fertile, yet free-draining soil with plenty of organic matter dug in.
I’ve always found that once established, the plant is resilient, but extra care and attention to the soil conditions may be required in the first year after planting, just to give it a head start.
When and how should creeping phlox be planted?
I planted the plugs around 40-50cm (15-20″) apart in the spring, and they performed very well.
I’ve seen gardeners grow them in pots in the autumn and then transfer them to the garden in the spring, so you could try this if you buy them later in the year.
Is creeping phlox prone to pests and diseases?
I didn’t experience any issues with creeping phlox in my garden, with no sign of the usual pests, bugs and diseases.
I’ve heard that powdery mildew can be an issue if creeping phlox is too compacted and this can be remedied by thinning them out and giving them some breathing space.
When does creeping phlox flower and how long for?
I managed to get around 3 weeks of blooms around May. Sometimes they flower in late April and sometimes into the first week of June.
How much water and fertiliser does creeping phlox require?
Creeping phlox is a resilient plant that I’ve found is fairly drought-tolerant once established.
Extra care and attention to the soil’s moisture is required in the first year until the phlox is established. The ideal soil during the first year is moist but free-draining – phlox plants dislike soggy soil, which can lead to root rot.
I’ve always applied a balanced feed once or twice a year, with the first dose in early spring and the second during the flowering period later in spring or early summer. I had great results at my previous property with this method, and I see no need to apply feed more often.
Is creeping phlox toxic or harmful to humans and pets?
Creeping phlox is not toxic and is included in several lists of plants that are safe for households with pets.Â
I have handled it several times and never had any skin issues, despite having sensitive skin.
How to Care For Creeping Phlox After It’s Finished Flowering
I’ve found creeping phlox to be an easy plant to grow once established, but you may find my tips below helpful:
Pruning
I always pruned creeping phlox after it had finished flowering and by using sheers. I never felt the need to be exact as I’ve seen phlox recover well from aggressive pruning like this.
If the plant is mature and the stems have become leggy, a more aggressive prune may be required, I have seen gardeners chop off up to half the height and it still recovered.
If you prefer your phlox compact, try pruning each year to form a mounded shape, this is what I did and it still “crept” the following year.
Disease Prevention
Creeping phlox is generally disease-free and I’ve never had any issues but you can lift, divide and replant if it becomes compacted. I know from my experience in growing it that phlox prefers some space and likes to breathe; it may suffer from powdery mildew if it doesn’t have enough space and the ground is too wet.
Propagation
The easiest way to create new plants is by division and I’ve increased my stock this way. I’ve taken root cuttings in late winter/early spring before but with mixed results.
Creeping Phlox Companion Plants
Creeping phlox is a popular groundcover plant and I’ve seen it grown under dozens, if not hundreds, of taller plants such as tulips, irises, alliums and rudbeckia.
It can also be combined with other ground covering plants in rockeries and along the edges of borders and paths. Grow with hostas, dianthus, aubrieta, lamb’s ear and more.
Based on my experience and where I’ve seen it grow, I don’t think you’ll have any problems finding plants to grow creeping phlox with.
Problem Solving: 4 Common Issues
While creeping phlox is a low-maintenance plant, and I haven’t experienced any notable issues, here are solutions to some problems you may come across:
1) Creeping Phlox Not Flowering
This is most likely due to a lack of sunlight. Phlox will survive in partial shade, but the more sunlight it receives, the more blooms you can expect. It could also be due to:
- Incorrect pruning, i.e. pruning at the wrong time and taking off the buds.
- Powdery mildew overtaking the plant (I’ve seen this, and it can be remedied by creating space).
- Leggy stems and an overgrown plant.
- Excessive nitrogen fertiliser, possibly as runoff from other plants/lawn etc.
2) Hollow Centre/Crown
I’ve seen this occur in older, mature plants that haven’t been pruned for years – the stems became leggy and the centre hollow with few blooms. I suggest pruning out the dead stems and trimming back to encourage new growth.Â
Follow these steps if you suspect crown rot.
3) Yellowing and Dying Phlox
This is most likely a fungal disease and possibly related to powdery mildew. It may occur in phlox grown in overly damp soil and spread via overhead watering. The issues could be compounded by lack of air circulation as phlox prefers space to breathe and grow. Leaf yellowing can also be due to nutrient deficiencies or overfeeding with specific fertilisers that block the uptake of some nutrients.
4) Aphids/Spider Mites
This is best treated with a spray but lately, I’ve been using sticky pads which are more eco-friendly. If you detect the bugs early enough, you can pinch them off and set up some sticky pads before they have the chance to spread.
Daniel’s Take on Creeping Phlox
Here is a quote from Daniel, our co-founder:
Creeping phlox is an excellent choice for rockeries but it’s also suitable for groundcover where it suppresses weeds and fills in space under taller plants. I love the way cascades over edges, it’s a stunning classic.
More Photos
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This guide was reviewed and fact-checked by qualified horticulturist Elizabeth Smith.
Explore: Elizabeth's profile and qualifications.
Meet The Author: Hannah Miller
Hannah is a keen gardener who grows organic fruit and vegetables in her Surrey garden and is moving towards a more sustainable lifestyle.Â
She is also the proud grower of a dahlia and herb garden.
Hannah worked for the NHS for 12 years but also has a level 3 qualification in horticulture and is currently studying for her level 4.
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