Ornamental · Polygonaceae
Mountain Fleece
Persicaria amplexicaulis
Give it steady moisture and room to spread, and mountain fleece rockets up red bottlebrush spikes from June to frost.
Full sun
Every 3–7 days
USDA 4–7
3–4 ft · 0.9–1.2 m
Overview
Mountain fleece is a hard-working perennial that keeps the color coming for months. From June into October it fires up slim red bottlebrush spikes above tidy clumps of green foliage, and the show hardly pauses for breath. It sits in the knotweed family yet keeps its cool, building a clump that eases wider instead of bolting.
Point it at the damp end of the garden and it takes off. It digs into average to wet soil, laps up full sun wherever the ground stays moist, and shrugs off part shade. Hardy right down to zone 4, it dies back each winter and charges back every spring, rising waist-high at 3 to 4 feet across.
Best of all, it barely asks a thing. Chop the old growth to the ground in late winter, split a tired clump every few years, and keep watch for aphids and slugs. Deer and rabbits skip right past it, which makes it a standout, low-effort pick for a border or a spot beside a pond.
Care
The short version: full sun to part shade, in soil kept consistently moist. Chop it to the ground in late winter, divide the clump every 3 to 4 years, and give each plant 3 to 4 feet of room to fill out.
Light
Mountain fleece hits its stride in full sun, though it takes partial shade or partial sun in good spirits. The one catch is moisture, because under full sun the soil has to stay damp or the plant flags once summer heat rolls in.
Water
This plant is thirsty, so keep the water coming. Hold the soil consistently moist, watering about every 3 to 7 days, and step it up in hot weather or strong sun. It even shrugs off wet ground and the edge of a pond.
Soil
Set it in average, medium to wet but well-drained clay or loam and it takes right off. It powers through steadily damp ground that would rot a fussier plant, and it stays easy about pH, romping across a wide band from 6.0 to 8.0.
Temperature
Mountain fleece is a cold-weather champ, hardy down to -29°F (-34°C) and happy up to around 86°F (30°C). It dies back in winter and springs right back, so a hard freeze never rattles an established clump.
Humidity
Outdoor humidity is whatever the sky hands over, and this plant rolls with all of it. What really fires it up is moist roots, not damp air.
Feeding
Keep the feeding light and it thanks you. Work a balanced general-purpose fertilizer or some compost into the soil at the start of the growing season in spring and call it done. Go easy, though, because too much nitrogen pumps out soft growth that aphids pile onto.
Pruning
Chop the whole plant back to the ground in late winter or early spring to open the way for fresh shoots. Then through summer, snip off the spent spikes to spur more bloom and rein in self-seeding.
Repotting
Mountain fleece is no container plant, but it does crave dividing every 3 to 4 years. Lift and split the clump the moment it loses steam, hollows out in the center, or starts pumping out fewer and smaller flower spikes.
Size & spacing
Count on a clump that shoots to 3 to 4 feet (91 to 122 cm) tall and just as wide. Hand each plant a matching 3 to 4 feet (91 to 122 cm) of room so it can fill out without elbowing its neighbors.
When to plant
Mountain fleece runs on an easy seasonal rhythm you can plan around. Kick things off with seed indoors in late winter, set young plants out in spring once the frost lifts or again in early fall, and the flower spikes barrel on from June all the way to October.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter to early spring (about 6-8 weeks before last frost)
- Plant: Spring after the last frost, or early fall
- Harvest: June to October
Hardiness
USDA hardiness zones: 4–7
Temperature: down to -34°C
Troubleshooting
Mountain fleece is a tough, healthy plant that rarely throws a curveball, so most of what you will run into is a chewed leaf or a storm-flattened stem. Match what you see below and pounce early, while the fix is still quick.
Tender shoot tips twisting under a swarm of little sap feeders
Spot bunched-up bugs twisting the fresh growth and you have found aphids, the pest mountain fleece attracts most. They crowd the tender shoots and leaf undersides, tap into the sap, and leave a sticky glaze behind. Knock them flying with a hard jet of water, follow up on the worst patches with insecticidal soap, and let the lady beetles and lacewings swoop in to finish the job.
Fix:
- Spray plants with a strong jet of water to dislodge aphids
- Apply insecticidal soap or horticultural oil to affected growth
- Encourage natural predators such as lady beetles and lacewings
Leaves munched into tatters and lacy openwork
Two chewers tear up leaves like this. Japanese beetles, the flashy copper-and-green ones, feast right out in the open by day, while slugs and snails raid overnight and leave slime trails near the soil. Pick the beetles off into soapy water at dawn, drop iron-phosphate bait for the slugs, and sweep away the damp debris they duck under, and the clump powers back fast.
Fix:
- Hand-pick Japanese beetles in early morning and drop them into soapy water
- Set out slug and snail traps or iron-phosphate baits
- Remove debris and mulch that shelter slugs and snails
Towering bloom stalks toppled by wind and driving rain
Those tall flower stems take a real beating from wind and heavy rain, and a big clump feels it hardest. Trim broken stems back with a clean cut and the plant fires off new growth. Ring an exposed clump with stakes or grow-through supports, and where you can, drop it into a spot that dodges the fiercest wind.
Fix:
- Remove broken stems with a clean cut
- Provide staking or grow-through supports for tall clumps
- Site plants in a location sheltered from strong wind
Self-sown newcomers springing up as the patch gains ground
Give mountain fleece a spot it loves and it self-seeds and creeps outward slowly on its rhizomes, so young plants pop up near the parent and the clump pushes wider year after year. This is a steady march, not a stampede, and the plant is not invasive. Snip the spent spikes before seed sets, pull the seedlings you skip while they are small, and split any clump that has outgrown its patch.
Fix:
- Deadhead spent flower spikes before seed sets
- Pull or transplant unwanted seedlings while young
- Divide and reduce clumps that have spread beyond their space
Toxicity
Got pets or kids? Plant away, because mountain fleece is non-toxic. The ASPCA leaves it off its list, and horticultural references report no serious toxicity, so it drops straight into a garden full of paws and small hands.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
A curious cat can prowl right up to mountain fleece and come away fine, since it never landed on the ASPCA toxic list. Chew a leaf and the worst that follows is a quick bit of stomach upset from the roughage.
Dogs None
Dogs romp around it with zero risk. Gulp down a mouthful of foliage and the stomach might loosen for an hour, the way any garden green can, but no real poison lurks in it.
Horses Safe
Horses graze near it without a hitch, since nothing toxic sits on the record. They rarely fancy the tough spikes anyway, so most breeze right past them.
Rabbits Safe
Rabbits can browse it and walk away just fine. It even earns a rabbit-resistant reputation, so they tend to skip it and dive for the softer plants nearby.
Livestock Safe
Cattle, goats, and sheep face no known danger from mountain fleece, and not a single case of it poisoning farm animals turns up on record.
Birds Safe
Birds flit around it in total safety. The small seeds and foliage carry nothing harmful, so it stays a friendly fixture of a wildlife border.
People Safe
Children can play right beside it with no worry at all. It grows purely for the show and poses no poisoning risk if a curious kid grabs or tastes it.
No special handling precautions are documented; as with any plant, discourage pets from chewing ornamental foliage to avoid mild stomach upset.
Varieties
Mountain fleece rolls out in a handful of named selections that differ mainly in size and flower color. These two are the ones you will spot most.
Firetail
A runaway favorite that fires off showy crimson to rose-red bottlebrush spikes from June clear into October.
Golden Arrow
A punchy compact pick that tops out at 18 to 24 inches tall and wide, throwing golden-green foliage against cardinal-red summer flowers.
Companions
Mountain fleece pairs best with plants that share its love of moist ground, and worst with anything that wants to stay dry.
Plant near
Ornamental grasses: Their upright vertical texture contrasts with the fleece flower spikes in borders and meadow plantings with similar moisture needs.
Astilbe: Shares a preference for moist soil and part shade, providing complementary plume-shaped blooms in similar conditions.
Keep apart
Drought-loving Mediterranean herbs such as lavender: These prefer dry, lean soil, which conflicts with the consistent moisture mountain fleece requires.
How to propagate
Mountain fleece is a breeze to multiply, whether you split an existing clump, let it self-sow, or take a cutting.
DivisionEasy
Spring or fall · One growing season
Chasing more mountain fleece? Division is the easiest and most reliable route by far. In spring or fall, dig up the rhizomatous clump, snap off a few healthy pieces, and drop them back in at the depth they came from. Each one grabs hold and fills out inside a single growing season.
SeedModerate
Late winter to spring indoors, or self-sown outdoors · One to two growing seasons to reach flowering size
It self-sows all on its own, and you can gather seed and start it indoors from late winter into spring. Hold your horses, though, because seedlings need one to two growing seasons to reach flowering size. And they may not come true, so a seed-grown plant can wander off from a named cultivar.
Stem cuttingsModerate
Late spring to early summer · Several weeks to root, one season to establish
Fancy a challenge? Take softwood basal cuttings from non-flowering shoots in late spring or early summer. They root over several weeks and need a full season to establish, though most gardeners grab the spade and divide instead.
Myths
Give mountain fleece one season and its knotweed genes will send it romping over every neighbor in the bed.
Not this one. Mountain fleece does self-seed and edge outward slowly where it thrives, but the record calls it flatly not invasive. It behaves nothing like its aggressive cousin Japanese knotweed, and one quick deadhead or division keeps it right in line.
Growing mountain fleece invites a poisoning risk for the family dog, the cat, and the kids.
Plant it and relax. The ASPCA leaves it off the toxic list, and horticultural references flag no serious toxicity concerns. It counts as a fully non-toxic ornamental, ready for a garden buzzing with pets and kids.