Tree · Cupressaceae
Juniper
Juniperus chinensis
Give it full sun and sharp drainage, and a juniper asks for almost nothing the rest of its long life.
Full sun
Every 7–14 days
USDA 3–9
1–59 ft · 0.3–18 m
Overview
Juniper is one of the toughest evergreens you can plant. It belongs to the cypress family and grows across the northern hemisphere, shrugging off cold, heat, drought, salt, and poor ground that would defeat most shrubs. The forms run from flat groundcovers a foot high to upright trees reaching up to 59 feet (18 m), all carrying the same aromatic, scale-like or needle-like foliage.
What sets juniper apart is how little it asks once it settles in. Give it sun and soil that drains and it will hold its color through winter, anchor a slope, screen a fence line, or stand alone as a sculptural specimen. The berry-like blue cones on female plants take about two years to ripen and draw birds through the cold months.
There is one firm limit worth knowing up front. Juniper grows slowly and will not resprout from bare old wood, so the plant you shape in the early years is more or less the plant you keep. Prune lightly and often rather than waiting for a hard cut later.
Care
The short version: full sun and fast-draining soil are the whole game. Water through the first year to settle the roots, then leave it largely alone, feed it rarely, and prune only into green growth.
Light
Juniper wants full sun, ideally 6 or more hours a day, and it will take a little partial sun. Push it into real shade and the growth thins, the color dulls, and disease moves in.
Water
Water a new juniper regularly through its first year to settle the roots. After that it's very drought tolerant and only needs help in a long dry spell, since the one thing it won't forgive is soggy soil.
Soil
Sharp drainage matters far more than richness here. Juniper handles sandy, rocky, and even clay ground as long as water moves through, and it's comfortable across a wide pH of 5.0 to 8.0.
Temperature
Few shrubs are this hardy. Juniper takes everything from about -29°F to 100°F (-34°C to 38°C), holding its foliage through hard winters and shrugging off summer heat.
Humidity
Outdoor humidity is whatever it is, and juniper doesn't mind. Air movement counts for more than any humidity level, since still, damp air around crowded foliage invites the tip blights.
Feeding
Juniper rarely needs feeding at all. If growth looks poor, a single light application of balanced or slow-release fertilizer in spring is plenty, and overfeeding does more harm than good.
Pruning
Shape it lightly in late spring and cut only into green growth, because bare old wood will not push new shoots and leaves a permanent gap. Pull off dead, diseased, or blight-killed tips during dry weather.
Repotting
Container and bonsai junipers want fresh room every 2 to 3 years. Repot when you see roots circling the pot, water running straight through, or growth slowing with yellowing foliage.
Size & spacing
Forms range hugely, spanning 1 to 59 feet (0.3 to 18 m) in height, with spreads of 2 to 20 feet (60 cm to 6 m). Match the cultivar to the space and give each plant room for air to move through the canopy.
When to plant
Juniper is planted, not sown, and the best windows are spring and fall when the soil is workable and the weather is mild. Set plants out then so the roots can establish before summer heat or winter cold, and water through that first season while they take hold.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: spring or fall
- Harvest: inconspicuous; blue berry-like female cones mature over about two years
Hardiness
USDA hardiness zones: 3–9
Temperature: down to -40°C
Troubleshooting
A juniper in the right spot stays trouble-free for years, so most problems trace back to wet soil or crowded, damp growth. Watch the new tips, the inner foliage, and the branches, and match what you see below before reaching for a spray.
Whole plant thinning and slowly declining
When a juniper sits in wet ground, Phytophthora root rot sets in and the foliage thins, dulls, and fades from the top down. The roots turn dark and rotten, and there is no easy cure once it takes hold. Fix the drainage, stop overwatering, and replace plants that are too far gone.
Fix:
- Improve drainage and stop overwatering
- Plant in raised beds and amend heavy clay with porous material such as ground pine bark
- Remove severely affected plants, as root rot is difficult to reverse
New shoot tips fading to brown and dying back
Two fungal tip blights cause this. Phomopsis tip blight attacks soft new growth in warm, wet weather, while Kabatina tip blight kills year-old twigs in spring through small wounds. Prune well below the dead tissue in dry weather, disinfect your tools between cuts, and open the plant up so air moves through it.
Fix:
- Prune out and destroy blighted tips well below the dead tissue during dry weather, disinfecting tools between cuts
- Improve air circulation by spacing and selective thinning
- Avoid overhead watering and wetting foliage
- Apply a labeled fungicide (mancozeb, thiophanate-methyl, or copper) protectively on new growth where blight is recurring
Needles stippled yellow, sometimes with fine webbing
Two sap-feeders give this look. Spruce spider mites stipple the needles in cool spring and fall weather and leave fine webbing, while juniper scale clings as tiny bumps and yellows the foliage. Tap a branch over white paper to spot moving mites, then knock them back with a strong jet of water or insecticidal soap, and treat scale with a dormant oil spray in late winter.
Fix:
- Dislodge mites with a strong spray of water
- Apply insecticidal soap or a labeled miticide for heavy mite infestations and preserve natural predators
- Apply 2-3 percent horticultural oil as a dormant spray in late winter for scale, or treat crawlers with a labeled insecticide
Spindle-shaped bags dangling from thinning branches
Those little carrot-shaped bags are bagworms, caterpillars that feed from inside a portable case stitched together with bits of foliage. A heavy crop can strip branches or kill a whole plant. Pick the bags off through fall and winter to clear the overwintering eggs, then spray Bt in spring while the larvae are still small.
Fix:
- Handpick and destroy bags in fall and winter to remove overwintering eggs
- Apply Bacillus thuringiensis (Bt) in spring while larvae are young and small
- Use a labeled insecticide for heavy infestations of older larvae
Woody galls sprouting orange jelly horns in spring
These galls are cedar-apple rust and its relatives, fungi that bounce between junipers and apple-family hosts like crabapple and hawthorn. The galls barely hurt the juniper itself, so the real reason to act is to protect nearby fruit trees. Cut the woody galls out before they push out their orange horns, and keep junipers well away from apples and crabapples.
Fix:
- Prune out and remove woody galls before they produce orange horns in spring
- Plant rust-resistant juniper cultivars
- Do not plant junipers within a few hundred yards of apples, crabapples, or hawthorns
- Apply a labeled fungicide (mancozeb or propiconazole) where control is needed, though galls do little harm to the juniper itself
Toxicity
Juniper is a low-worry plant around animals and people. It carries none of the toxins on the standard poison lists, and its sharp, bitter foliage usually keeps pets and livestock from eating much in the first place. The main thing to know is that the berry-like cones can mildly upset a stomach in quantity, and only a few species are the true culinary juniper used to flavor gin.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Caution
Juniper isn't poisonous to cats, and the sharp, aromatic foliage usually keeps them away. A cat that does chew a lot of the berry-like cones may get a brief, mild stomach upset that settles on its own.
Dogs Caution
Dogs can nose around a juniper without real danger, since it carries no listed toxins. If one eats a mouthful of the cones or oily foliage, expect nothing worse than some drooling or a loose stool for a day.
Horses Caution
The strong terpene scent makes juniper unpalatable, so horses tend to leave it alone. A horse that grazes a large quantity of berries may feel mild gut irritation, but the plant is not considered a poisoning risk.
Rabbits Caution
Rabbits rarely bother with the resinous needles, and juniper holds no toxin that threatens them. Keep any nibbling small, as the volatile oils can loosen the gut in larger amounts.
Livestock Safe
Cattle, goats, and sheep generally pass juniper by because of its bitter, aromatic foliage, and it is absent from the usual lists of plants that poison them.
Birds Safe
Birds eat the ripe blue cones freely and help spread the seed, so the fruit poses no problem for them at all.
People Edible with care
The berries of certain species, mainly Juniperus communis, are the spice that flavors gin, but ornamental landscape junipers are not all edible and some cones can upset the stomach. Treat only known culinary species as food, and handle the prickly, oily foliage with gloves.
The aromatic foliage and berry-like cones may cause mild, self-limiting stomach upset if eaten in quantity, and the prickly juvenile needles plus juniper oils can mildly irritate skin, so wear gloves when pruning. This is irritation, not poisoning.
Varieties
Junipers come in more forms than almost any other evergreen, from creeping mats to pencil-thin columns. These are the ones you'll meet most often in the nursery.
'Hetzii'
A vigorous, wide-spreading blue-green shrub that earns its place in big foundation plantings and screens.
'Sea Green'
A compact, fountain-shaped shrub with arching branches and rich mint-green foliage that makes an easy low hedge.
'Spartan'
A narrow, dense, dark green column that reaches about 15 to 20 feet tall but only around 5 feet wide, the classic upright screen.
'Hollywood' / 'Kaizuka'
An irregular, twisted upright with rich green foliage that gardeners grow as a living sculpture.
Juniperus scopulorum 'Skyrocket'
A pencil-thin blue-gray column so narrow it works as a vertical accent in the tightest spots.
Juniperus squamata 'Blue Star'
A dwarf mounding shrub of 1 to 3 feet, packed with dense silvery blue-gray needles.
How to propagate
How you multiply a juniper depends on what you're after, since named cultivars won't come true from seed and have to be cloned by other means.
Stem cuttingsModerate
Late fall through winter from semi-hardwood to hardwood growth · Several weeks to a few months to root
Most cultivars are grown from cuttings so they stay true to the parent. Take semi-hardwood to hardwood pieces from late fall through winter, dip them in rooting hormone, and set them in well-drained media, where they root over several weeks to a few months.
GraftingDemanding
Winter under glass · Weeks to months
Grafting is the route for upright tree forms and choice cultivars that won't root from cuttings. It's done in winter under glass and takes weeks to months to knit together, which is why it stays in the hands of skilled growers.
LayeringEasy
Spring · Several months to a year
Layering is the simplest method for the low, spreading kinds. Pin a trailing branch to the soil in spring and it will root in place over several months to a year, which suits groundcover and shrub forms well.
SeedDemanding
After cleaning and cold stratification · Slow and erratic, often more than a year to germinate
Seed is mostly for raising species rather than named cultivars, which don't come true this way. Clean the cones and give the seed a cold stratification, then wait, since germination is slow and erratic and often takes more than a year.
Myths
Berries from any landscape juniper are safe to harvest and eat like the ones used to flavor gin.
Only a few species, mainly Juniperus communis, are grown as a culinary spice. Many ornamental junipers carry berry-like cones that taste bad and can bring on mild stomach upset, so don't assume the berries on a landscape juniper are edible.
You can rejuvenate an overgrown juniper by cutting it back hard into the old bare wood.
Junipers won't push new shoots from old leafless wood, so a hard cut into bare branches leaves a permanent dead hole. Always prune into green, foliage-bearing growth and shape the plant a little at a time.