Rhododendron
Rhododendron
Shallow-rooted and acid-loving — a thick mulch and rainwater matter more here than anything you could feed it.
- Type
- Shrub · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Green
- Flower color
- Pink
- Sunlight
- Partial shade, sheltered from cold winds.
- Watering
- Keep it moist with rainwater; this matters most through summer.
- Feeding
- An ericaceous feed once flowering is over.
- Frost tolerant
- Yes
- Flowering
- April
- Pruning
- Deadhead after flowering, taking care not to cut off the new buds.
- Mar–Apr Bud Break
- Apr–Jun Flowering
- Jun–Dec Growing
- Jan–Mar Growing
- Plant spacing
- 6 ft 7 in
- In-row spacing
- 6 ft 7 in
- Between rows
- 8 ft 2 in
- Square-foot density
- Not suited to SFG
- Root system
- A fine surface mat, and nothing below it
- Working depth
- 4–12 in
- Can reach
- 18 in down where the soil allows
- Spread
- 6.5–10 ft across, about 1–1.5× the width of the plant
- Shallowest pot
- 16 in of soil
Hair-fine roots in a shallow felt, with no deep anchor to fall back on. It cannot chase water, so it is the first casualty of a drought and the first thing killed by a hoe. Mulch it, never cultivate around it, and never let it go dry in its first two summers.
A shallow plate of hair-fine roots and no anchor beneath it, which is why a rhododendron can be lifted and moved almost at any age and why it dies of drought so easily. Plant it high, mulch it deeply, and never let it go dry in summer.
The habit is Rhododendron’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.
- Cats and dogs
- Recorded toxic
Recorded as toxic to cats and dogs by ASPCA.
Both the ASPCA row and our own catalog name only the genus, so the statements match. Azalea and Rosebay are the same row.
- Vine weevil Adults notch leaf edges at night; their plump C-shaped grubs devour roots, especially in containers. Hand-pick adults after dark and water in biological nematodes in late summer.
- Peony botrytis blight Rhododendron bud blast
- Phytophthora root and foot rot A waterborne rot of woody plants that kills from the roots up: the whole plant fades and wilts, and the bark at the base is stained rusty-brown beneath.
- Powdery mildew A white dusty coating over leaves and shoots when roots are dry but the air is humid. Keep plants watered and mulched, prune for airflow, and remove the worst leaves.
Beneficial predators that hunt this plant's pests — grow their favourite flowers nearby to recruit them. companion plant
- Beneficial nematodes Steinernema & Heterorhabditis spp.Hunts Vine weevil
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.
- Frogs & toads AnuraHunts Vine weevil
A resident toad works the beds every night for slugs, cutworms, and weevils. Recruit them with water — even a sunken basin pond — plus damp shade and an upturned-pot toad house; skip the slug pellets that poison their prey.
- Ground beetle CarabidaeHunts Vine weevil
Fast, glossy night hunters that patrol the soil surface for slugs, cutworms, and root-fly larvae. Give them daytime cover — thick perennial edges, stepping stones, a log — and skip the tillage that wrecks their burrows.
- Hedgehog Erinaceus europaeusHunts Vine weevil
A European animal, and worth saying so plainly: there are no hedgehogs in North America, and the ally that does the same night shift here is the toad, the opossum or the ground beetle. Where they do occur, cut a gap in the fence and skip the pellets.
Camellia, Azalea, Pieris, Ferns
Green-leaved shrubs, like this one.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com