Ornamental · Polygonaceae
Mountain Fleece
Persicaria amplexicaulis
Offer it steady moisture and a little room, and mountain fleece rewards you with 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 forgiving, good-natured perennial that gives back months of color for very little fuss. From June into October it lifts slim, red bottlebrush spikes over tidy mounds of green leaves, and the display hardly pauses. It sits in the knotweed family yet minds its manners, building a clump that widens gently instead of running off.
Think of this as a friend for the damp corner of the garden. It settles happily into average to wet soil, takes full sun wherever the ground stays moist, and copes cheerfully with part shade. Hardy right down to zone 4, it fades back each winter and comes home faithfully every spring, rising waist-high at 3 to 4 feet across.
The care it asks of you is small and easy to keep up with. Trim the old growth to the ground in late winter, refresh a tired clump every few years, and glance now and then for aphids and slugs. Deer and rabbits usually leave it be, which makes it a calm, dependable choice for a border or a spot beside a pond.
Care
The short version: full sun to part shade, in soil kept steadily moist. Trim 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 settle in comfortably.
Light
Mountain fleece is happiest in full sun, though it takes partial shade or partial sun in good grace. The one thing to remember is moisture, because in full sun the soil has to stay damp, or the plant will wilt in the heat of summer.
Water
This is a plant that loves a drink, so there is no need to hold back. Keep the soil steadily moist, watering about every 3 to 7 days, and reach for the can more often in hot spells or strong sun. It even shrugs off wet ground and the edge of a pond.
Soil
Give it average, medium to wet but well-drained clay or loam and it will thrive. It copes with steadily damp conditions that would rot fussier plants, and it is relaxed about pH, growing across a comfortable span from 6.0 to 8.0.
Temperature
Mountain fleece is wonderfully cold-hardy, down to -29°F (-34°C), and easy up to around 86°F (30°C). It dies back over winter and returns each spring, so even a hard freeze is no worry for an established clump.
Humidity
Outdoor humidity is simply whatever the day brings, and the plant is content either way, so you can put that off your list. What it truly asks for is moist roots, not damp air.
Feeding
Keep feeding light and simple. Work in a balanced general-purpose fertilizer or a little compost at the start of the growing season in spring, and that is usually all it needs. Go gently, since too much nitrogen makes the soft growth aphids favor.
Pruning
Cut the whole plant right back to the ground in late winter or early spring to make room for fresh shoots. Through summer, nip off the spent spikes to coax more bloom and gently curb self-seeding.
Repotting
Mountain fleece is not a container plant, but it does appreciate dividing every 3 to 4 years. Lift and split the clump when it loses vigor, hollows out in the middle, or begins offering fewer and smaller flower spikes.
Size & spacing
Picture a clump that grows to 3 to 4 feet (91 to 122 cm) tall and just as wide. Leave each plant a matching 3 to 4 feet (91 to 122 cm) of room so it can fill out in comfort without crowding its neighbors.
When to plant
Mountain fleece keeps to an easy, forgiving seasonal beat. Sow seed indoors in late winter, move young plants outside in spring once the frost has gone or again in early fall, and the flower spikes will carry you 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 sturdy, healthy plant that rarely gives real trouble, so most of what you will run into is a chewed leaf or a stem knocked flat by a storm. Match what you see below and step in early, while every fix is still quick and simple.
New shoots curling with tiny insects gathered on them
Take heart, because those clustered little bugs are just aphids, the most familiar visitor mountain fleece gets, and they are easy to handle. They gather on soft new shoots and leaf undersides to sip sap, leaving a sticky film behind. A firm spray of water knocks most of them off, insecticidal soap settles the heavier patches, and the lady beetles and lacewings that arrive will happily see off the rest.
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
Chewed holes and thinned patches showing up on the leaves
Don't worry, this ragged chewing has two easygoing suspects. The metallic copper-and-green Japanese beetles feed openly in daylight, while slugs and snails do their work after dark and leave telltale slime near the soil. Pick the beetles off into soapy water each morning, scatter a little iron-phosphate bait for the slugs, and tidy away the damp debris they shelter in, and your clump will bounce back.
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
Tall stems leaning over or snapped once a storm passes
It looks worse than it is when a big clump takes a knock from wind and heavy rain, and the plant recovers well. Trim any broken stems back with a clean cut so fresh growth can follow. A ring of grow-through supports or a few stakes steadies an exposed clump, and if you can tuck it into a spot out of the worst wind, it will thank you.
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
A few stray seedlings and a clump quietly getting wider
There is nothing to fear here, since mountain fleece only self-seeds and creeps slowly by rhizome where it feels at home, so a few youngsters appear near the parent and the clump eases outward year by year. This is a gentle, steady habit and the plant is not invasive at all. Snip the spent spikes before seed forms, lift out any seedlings you would rather not keep, and divide a clump once it fills its space.
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
Reassuring news for a home with pets or children: mountain fleece is non-toxic. The ASPCA does not list it, and horticultural references note no serious toxicity, so you can plant it freely in a garden that sees plenty of paws and small hands.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
You can relax about a curious cat here, since mountain fleece never made the ASPCA toxic list, and the worst a nibbled leaf might bring is a little passing stomach upset from the roughage.
Dogs None
Your dog is in safe company with this plant. A stolen mouthful of leaves may loosen the stomach for an hour, as any garden greenery can, yet it holds no genuine poison.
Horses Safe
Rest easy about horses, because nothing toxic is on record and grazing does them no harm. They rarely bother with the tough spikes anyway, so most simply wander past.
Rabbits Safe
Rabbits can browse it with no worry at all. It is actually noted as rabbit-resistant, so they usually skip it and choose the softer plants close by.
Livestock Safe
Cattle, goats, and sheep have nothing to fear from mountain fleece, and no case of it poisoning farm animals has ever been recorded.
Birds Safe
Birds are perfectly fine around it. Neither the small seeds nor the foliage carry anything harmful, so it sits happily as a gentle part of a wildlife border.
People Safe
You can welcome children near mountain fleece without concern. It is grown only for looks and poses no poisoning risk if a little one handles 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 comes in a small, friendly handful of named selections that differ mostly in size and flower color. These two are the ones you will meet most often.
Firetail
A much-loved cultivar you will reach for again, holding warm crimson to rose-red bottlebrush spikes from June right through October.
Golden Arrow
A neat, compact choice that keeps to a friendly 18 to 24 inches tall and wide, setting golden-green leaves 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 joy to multiply, whether you split a clump you already have, let it sow itself, or try a cutting.
DivisionEasy
Spring or fall · One growing season
If you want more mountain fleece, dividing is the kindest and most dependable route, and it is hard to get wrong. Wait for spring or fall, ease the rhizomatous clump up, part off a few healthy pieces, and settle them back at the depth they came from. Each piece finds its feet and fills out within a single growing season.
SeedModerate
Late winter to spring indoors, or self-sown outdoors · One to two growing seasons to reach flowering size
The plant sows itself with ease, and you are welcome to gather seed and start it indoors from late winter into spring. Give it time and patience, since seedlings take one to two growing seasons to reach flowering size. Do bear in mind they may not come true, so a seed-grown plant can wander a little from a named cultivar.
Stem cuttingsModerate
Late spring to early summer · Several weeks to root, one season to establish
You are also free to try softwood basal cuttings from non-flowering shoots in late spring or early summer. They root over several weeks and want a full season to settle, though most gardeners find division simpler and happily lean on it.
Myths
All knotweeds are dangerously invasive, so mountain fleece will take over the garden.
You can set that fear aside. Mountain fleece does self-seed and edge outward slowly where it is content, yet it is plainly described as not invasive. It behaves nothing like its aggressive cousin Japanese knotweed, and a quick deadhead or division keeps it right where you want it.
Mountain fleece is poisonous and unsafe to grow around pets and children.
Good news for a shared garden: the ASPCA does not list it as toxic, and horticultural references note no serious toxicity concerns. It counts as a fully non-toxic ornamental, so it is safe among pets and kids.