Alternanthera
Alternanthera is a flower in the Amaranthaceae family. It grows best in full sun to part shade with medium moisture, and is listed for USDA zones 2-13. Plants reach maturity about 70–77 days after planting and sit about 12 inches apart.
Varieties
1 from True Leaf Market · sorted by days to maturity▸Purple Knight70–77 days
Container; Annual
70-77 Days to maturity. Alternanthera dentata. Alternanthera Purple Knight Seeds. Non-GMO, Annual or Perennial. Purple Knight Alternanthera seeds promise an exotic and neat ornamental foliage ideal for many humid gardens across North America. Purple Knight seeds mature into robust mounded shrubs of rich purples and reds unfurling out for an eye-catching trim along walkways, borders, and fences. Alternanthera is native to the year round warmth of Asia, Africa, and Australia and will thrive all season in similar climates. Purple Knight alternanthera is easy to grow from seed and guarantees a unique and low-maintenance ground cover for any residential or commercial property.
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Plant spacing
In a square-foot bed, space alternanthera about 12 in apart — that fits 1 plant in each 1-foot square (1×1). Wider rows or containers space the same.
Plan your alternanthera planting
Add alternanthera to a free GardenDraft plan and get sow, transplant, and harvest dates computed for your ZIP code — with a drag-and-drop bed layout and reminders when it’s time to plant.
Start your free plan →At a glance
Growing timeline
Care & troubleshooting— extension-sourced, with citations
When to feed, prune & water
Mulch to suppress weeds and retain moisture
Mulch- Routine careApply organic mulch around plantsstrong evidence — extension confidence
Spread a few inches of straw, shredded leaves, or compost around established plants (keeping it off stems) to hold soil moisture, suppress weeds, and moderate soil temperature; wait until soil has warmed for heat-loving crops.
Plan crop rotation
Rotation- Routine careRotate plant families between bedsstrong evidence — extension confidence
Avoid planting the same family in the same bed in consecutive years (aim for a 3+ year gap), grouping crops by family so soilborne diseases and pests that build up don't carry over to the next susceptible crop.
- Routine careSequence for soil healthmoderate evidence — extension confidence
Follow heavy feeders like tomatoes and brassicas with legumes or a cover crop to support soil fertility and structure, and keep simple notes each year so you can track where each family grew.
Protect the garden from rabbits and voles
Protection- Routine careFence out rabbitsstrong evidence — extension confidence
Surround beds with 1-inch mesh chicken wire at least 2 feet tall with the bottom buried or staked down a few inches so rabbits can't push under it.
- Routine careReduce vole habitat and guard stemsstrong evidence — extension confidence
Keep grass and mulch pulled back from plant bases and crowns to remove vole cover, mow surrounding vegetation, and use hardware-cloth guards around vulnerable woody stems before winter.
Thin beet-family seedlings
Thinning- Routine careThin clusters to one plant each· every 2 wks · ~2 wksstrong evidence — extension confidence
Beet/chard 'seeds' are clusters, so several sprout together. Thin to one strong seedling every 3-4 in; the thinnings are edible greens.
Clean up debris and sanitize at season end
SanitationUnusual this time of year.
- Routine careRemove spent plants and fallen debrisstrong evidence — extension confidence
Pull and clear old plants, dropped fruit, and leaf litter at season end, since many pests and diseases overwinter in this debris; dispose of diseased material rather than composting it.
- Routine careClean tools, stakes, and cagesmoderate evidence — extension confidence
Wash and sanitize stakes, cages, and tools that touched diseased plants before storing or reusing them to avoid carrying pathogens into next season.
Something looks wrong?
Describe what you see on your alternantheraand we'll rank the likely causes — most likely first, least-invasive fix first.
Blister beetles
Pestmoderate- CulturalHand-pick wearing gloves· every 2 daysmoderate evidence — extension confidence
Wear gloves (these beetles release a blistering fluid) and knock beetles into soapy water, or use row cover ahead of swarms; their larvae eat grasshopper eggs, so tolerate light feeding when you can.
- OrganicSpot-treat heavy swarms· every 1 wkmoderate evidence — extension confidence
If a large swarm threatens a planting, a pyrethrin or other labeled insecticide can knock them back per the label; avoid spraying open blooms to protect pollinators.
Cercospora leaf spot on beet and chard
Diseasemoderate- CulturalRotate, space out, and water at the basestrong evidence — extension confidence
The fungus survives on debris and spreads by splashing water, so rotate beds, space plants for airflow, and water at the soil rather than overhead. Remove and discard heavily spotted outer leaves and clear crop residue after harvest.
- OrganicApply a copper fungicide if spreading· every 10 daysmoderate evidence — extension confidence
If spotting is severe and weather stays warm and humid, apply a labeled copper fungicide preventively per the label, before the disease takes over the planting.
Japanese beetles
Pestmoderate- CulturalHandpick into soapy water· every 1 days · ~4 wksstrong evidence — extension confidence
In early morning when beetles are sluggish, knock them into a bucket of soapy water; daily removal also reduces the scent that draws in more beetles. Skip the lure traps, which tend to attract more beetles than they catch.
- CulturalCover plants past bloommoderate evidence — extension confidence
On crops that have finished flowering and set fruit, drape a row cover or netting to keep beetles off without blocking pollination during bloom.
Potassium deficiency
Deficiencymoderate- CulturalConfirm with a soil test firststrong evidence — extension confidence
Edge scorch on older leaves has several causes, so get a soil test before adding potassium; over-applying can lock out magnesium and calcium.
- OrganicApply potassium per soil-test guidancemoderate evidence — extension confidence
If the test confirms low potassium, apply a potassium source (such as sulfate of potash) at the labeled/test-recommended rate and keep watering even, since drought worsens uptake.
Slugs & snails
Pestmoderate- CulturalTrap, hand-pick at night, reduce cover· every 2 days · ~3 wksstrong evidence — extension confidence
Pick at night with a flashlight, set shallow beer traps, water in the morning so soil dries by dusk, and clear damp hiding spots.
- OrganicIron-phosphate bait - label use only· every 1 wk · ~3 wksmoderate evidence — extension confidence
Scatter a labeled iron-phosphate slug bait sparingly per the label; it's pet- and wildlife-safer than metaldehyde.
Wireworms
PestmoderateUnusual this time of year.
- CulturalRotate away from grassy groundstrong evidence — extension confidence
Avoid planting susceptible crops right after sod, pasture, or grass cover, where wireworms build up; rotate to a less-favored crop and let infested beds dry out between plantings.
- CulturalBait-trap to monitor· every 5 days · ~3 wksmoderate evidence — extension confidence
Bury pieces of carrot or potato or a handful of soaked wheat seed as bait when soil reaches about 50F, check after several days, and remove the worms you find to gauge and reduce pressure.
Aphids
Pestlow- CulturalBlast off with water· every 3 days · ~2 wksstrong evidence — extension confidence
Knock colonies off with a strong jet of water in the morning; repeat every few days. Light infestations rarely need more.
- OrganicInsecticidal soap - label use only· every 1 wk · ~3 wksmoderate evidence — extension confidence
For persistent colonies apply insecticidal soap to undersides per label. Avoid open flowers.
Bolting (premature flowering)
Disorderlow- CulturalShade and harvest before boltingstrong evidence — extension confidence
Once a plant bolts it can't be reversed, so harvest at the first sign of stalk formation; 30-50% shade cloth and steady watering during heat help delay bolting in cool-season crops.
- CulturalUse bolt-resistant varieties and succession sowmoderate evidence — extension confidence
Choose heat-tolerant, slow-bolt varieties and stagger small sowings so a heat spell doesn't take out the whole planting.
Leaf miners
Pestlow- CulturalPick mined leaves + row cover· every 5 days · ~3 wksmoderate evidence — extension confidence
Remove and bag leaves with tunnels, and cover plants with insect netting to block the egg-laying flies. Damage is mostly cosmetic on leafy crops.