Use with caution
All parts of rhododendrons and azaleas are seriously toxic - they contain grayanotoxins that can cause drooling, vomiting, weakness, an abnormal heartbeat, and even coma in dogs, cats, and horses, and they are poisonous to people too. Plant where pets and children will not graze it, and never eat any part.
PJM Rhododendron
Rhododendron 'PJM'
flowerPJM is the rhododendron for cold climates, a famously tough hybrid group that survives where most rhododendrons fail. It forms a compact, rounded evergreen shrub three to six feet tall and wide, clothed in small, leathery, dark green leaves that take on rich mahogany-purple tones through winter, and in mid-spring, ahead of most rhododendrons, it covers itself in showy clusters of bright lavender-pink flowers. Bred by the Weston Nurseries in Massachusetts, the PJM group is prized for cold hardiness (often to zone 4), good sun tolerance for a rhododendron, and strong resistance to root rot. It is the easiest rhododendron for the northern garden, excellent massed, in foundation plantings, or in a woodland border.
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Sun
partial shade
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Water
Every 7 days
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Bloom
~30 days
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Difficulty
medium
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Lifecycle
perennial
Comes back every year
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Spacing
3-5 ft apart
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Planting Depth
Plant slightly high, top of root ball at or just above grade; mulch the shallow roots
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Soil pH
5.0-5.5
Growing Details
Soil Type
Acidic, moist, well-drained
Hardiness Zones
Zones 4 – 8
When to Fertilize
After bloom in spring with an acid fertilizer
Fertilizer
Acid-forming (rhododendron/azalea) fertilizer
🌱 Growing Guide
Grow PJM rhododendron in part shade, ideally dappled or high shade, though it takes more sun than most rhododendrons; in hot regions protect it from scorching afternoon sun, and everywhere shelter it from harsh drying winter wind. It demands acid soil - a pH of about 5.0 to 5.5 - that is moist, rich in organic matter, and very well-drained, because like all rhododendrons it cannot tolerate wet feet and rots in soggy ground; amend heavy clay and plant the root ball slightly high. It is hardy in zones 4 to 8. Keep a two to three inch organic mulch over the shallow roots and water in dry spells, never letting it bake dry. Prune, if at all, right after bloom, since it sets next year buds in summer; little pruning is usually needed.
🌼 Have a different variety?Cultivars of the same species usually share the same basic care, and they differ mainly in flower color, height, and bloom form, not in how you grow them. So this guide still applies even if your exact variety isn't the one shown.
Planting Calendar
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Direct sow
Apr 15
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Projected first bloom
May 15
JJan
FFeb
MMar
AApr
MMay
JJun
JJul
AAug
SSep
OOct
NNov
DDec
✅ Plant alongside
Good neighbors that attract beneficial insects or deter pests
- Azalea: A close relative that shares the exact acid soil and part shade and extends the rhododendron bloom season
- Ferns: Woodland companions that enjoy the same moist, acid, shaded soil and soften the shrub base
- Hosta: Bold foliage that fills the shade around the evergreen rhododendron in the same rich soil
🛡️ Pest & disease prevention
Proactive ways to stop trouble before it starts. Tap a name with an arrow for its full guide
Sucks sap from leaf undersides and stipples the tops grayish, worst on plants in too much sun - keep it in part shade, check leaf undersides, and treat early; PJM is fairly resistant
Fine stippling in hot dry weather - rinse the foliage and keep the plant from drought stress
Phytophthora kills rhododendrons in wet soil - the best defense is sharp drainage and planting slightly high; PJM is more resistant than most but still needs it
Cluster on new growth and buds - rinse off with water and encourage ladybugs
🌸 Blooms & cutting
PJM rhododendron is grown for the garden display rather than for cutting, though a few flowering branches make a handsome short-lived indoor arrangement - cut them in the cool morning as the buds open. The real care is simply timing any pruning for right after the flowers fade, since the plant forms next spring buds over summer; deadheading the spent trusses (snapping them off just above the new growth) tidies the plant and channels energy into next year bloom. Keep the shallow roots mulched and evenly moist year-round.
🥗 Nutrition & benefits
An ornamental cold-hardy evergreen grown for its bright early-spring flowers and year-round foliage. The blooms offer nectar to early bees and the occasional hummingbird, but every part is toxic, so its value is purely ornamental - do not let it be eaten.
⚠️ Toxicity & safety
All parts of rhododendrons and azaleas are seriously toxic - they contain grayanotoxins that can cause drooling, vomiting, weakness, an abnormal heartbeat, and even coma in dogs, cats, and horses, and they are poisonous to people too. Plant where pets and children will not graze it, and never eat any part.
For educational and informational purposes only. HomeSown is not medical, health, or other professional advice. Always positively identify any plant before handling or eating it; some plants, and some parts of otherwise-edible plants, are toxic. Consult a qualified professional before consuming or otherwise using any plant, especially if you are pregnant, nursing, taking medication, or have a health condition.