Lythrum
Lythrum virgatum
Slim magenta spikes for ground that stays damp — it seeds itself freely, so deadhead before it travels.
- Type
- Flower · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Green
- Flower color
- Pink · Red
- Sunlight
- Full sun or partial shade both suit it.
- Watering
- Wants the soil damp at all times.
- Feeding
- Feeding is unnecessary.
- Frost tolerant
- Yes
- Flowering
- June
- Pruning
- Deadhead through the season, then cut it down in late winter.
- Overwintering
- Fully hardy; it dies back on its own.
- Mar–Jun Spring Growth
- Jun–Sep Flowering
- Sep–Nov Growing
- Nov–Dec Leaf Fall
- Jan–Mar Leaf Fall
- Plant spacing
- 17.7 in
- In-row spacing
- 17.7 in
- Between rows
- 22 in
- Square-foot density
- Not suited to SFG
- Root system
- Clumping rhizomes
- Working depth
- 6–16 in
- Can reach
- 24 in down where the soil allows
- Spread
- 18 in–2 ft across, about 1–1.5× the width of the plant
- Shallowest pot
- 10 in of soil
The clump widens a little each year from a shallow rhizome that likes to sit at or just under the surface. When the middle goes bare and woody, lift the whole thing, keep the young outer pieces and throw the centre away.
The habit is Lythrum’s own; the figures are what that habit usually comes to at this size, not a measurement of this species. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
Beneficial predators that hunt this plant's pests — grow their favourite flowers nearby to recruit them. companion plant
- Assassin bug ReduviidaeHunts Japanese beetle
A patient ambusher with a curved beak it drives into whatever it catches — caterpillars, beetles, bugs, and the occasional bee, so count it a generalist rather than a specialist. It will jab a careless finger too, so admire it and leave it be.
- Beneficial nematodes Steinernema & Heterorhabditis spp.Hunts Japanese beetle
Microscopic worms watered onto damp soil that hunt down soil-dwelling grubs and release a bacterium that kills them within days. Timing is the whole thing: warm, damp soil and a small target grub, which means late summer for most of what they are used against.
- Garden birds PasseriformesHunts Japanese beetle
Both things are true: birds strip your currants and a brood of blue tits takes several thousand caterpillars out of one fruit tree in a fortnight. Net what you must and welcome them everywhere else — a nest box near the apples is worth more than a spray.
- Praying mantis MantidaeHunts Japanese beetle
A sit-and-wait ambusher that snatches caterpillars, beetles, and anything else that wanders close — friend and foe alike, so count it a mixed blessing. Tall, structured plantings give it perches and egg-case anchors.
- Spined soldier bug Podisus maculiventrisHunts Japanese beetle
A predatory stink bug — same shield outline as the pest, but with a sharp spine at each shoulder and a beak it uses to spear caterpillars and beetle grubs. Learn the spines before you squash a shield bug, because this one is on your side.
- Tachinid fly TachinidaeHunts Japanese beetle
Bristly, house-fly-lookalike parasitoids that lay eggs on caterpillars, beetle grubs, and earwigs — the maggot consumes the host from within. Adults sip nectar from shallow umbels and daisies.
Green-leaved flowers, like this one.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com