Honeysuckle

The scented one is the invasive one

Two honeysuckles are commonly planted in American gardens and they are not interchangeable.

Japanese honeysuckle, Lonicera japonica, is the one with the powerful sweet evening scent that most people picture. It is also a documented invasive across much of the country, smothering native vegetation and pulling down young trees.

Trumpet honeysuckle, Lonicera sempervirens, is the eastern native this entry records. NC State is direct about the trade: the flowers are non-fragrant. They are scarlet to orange-red outside and yellowish inside, an inch and a half to two inches long, and they are one of the best hummingbird plants there is.

So the honest framing is a choice rather than a substitution. If what you want is the scent, the native does not provide it. If what you want is a well-behaved climber that feeds hummingbirds for months, this is the plant, and the invasive one is not worth the risk.

Telling the honeysuckles apart in the field

The name covers a native vine, an invasive vine and a group of invasive shrubs, and the shrubs are what most complaints are actually about. Two questions settle it in seconds: is it a vine or a shrub, and if it is a shrub, is the stem hollow?

The hollow stem test

This is the single most useful piece of honeysuckle identification and it takes one cut. Snap or cut a young stem on a shrubby honeysuckle and look at the center: the invasive bush honeysuckles have a hollow brown pith. Native shrubs in the same size class have solid stems. It works in winter, it works on a plant that is not flowering, and it does not require getting the species right.

A second giveaway is the calendar. The invasive shrubs leaf out very early in spring and hold their leaves well into fall, which is exactly how they shade out everything beneath them. A stand of shrubs that is green in a woodland when nothing else is, in either direction, is almost always this group.

Honeysuckle in Michigan and the Great Lakes

Michigan is where this comes up most, and the confusion is largely a naming problem. What is regulated and removed there is the invasive shrub group above, listed by the state and by MSU Extension. What is called bush honeysuckle in a native-plant context is Diervilla lonicera, a low native shrub that is a different genus entirely and is recommended as a replacement rather than a problem.

Beyond Diervilla, the Great Lakes native alternatives usually named for the same job are New Jersey tea, Ceanothus americanus; Carolina rose, Rosa carolina; fragrant sumac, Rhus aromatica; and red osier dogwood, Cornus sericea. For the vine, the native trumpet honeysuckle on this page is the answer.

What it wants

Hardy in zones 4a to 9b, climbing 10 to 20 feet with a spread of 3 to 6, at a rapid growth rate.

Full sun or partial shade at two to six hours, with the best flowering in full sun.

Soil should be medium moisture, well drained and humus-rich, at a pH anywhere from acidic to neutral.

It is a twining vine, so it needs something to wrap around: a trellis, arbor or fence. It cannot climb a flat wall, and left on the ground it sprawls as a groundcover, which is a legitimate use.

Two rules that decide the flowering

1. Do not prune until after flowering

   It flowers on new growth, so NC State’s instruction is to wait. A tidy-up in early spring removes the display.

2. Do not feed it nitrogen

   High nitrogen fertilizer produces foliage at the expense of flowers. This is stated plainly and it is the commonest self-inflicted problem on flowering climbers.

3. Give it a real support from the start

   Twining stems need something to wrap. Wires, a trellis or an arbor, in place before planting.

4. Full sun for flowers

   It grows perfectly well in part shade and flowers noticeably less.

5. Keep it off the house

   See the fire note below.

Which coral honeysuckle to buy, and why Major Wheeler is the one

The species has one real weakness in a home garden, which is powdery mildew in hot humid summers, and one habit that disappoints, which is a heavy flush of flower in late spring followed by comparatively little afterwards. Cultivar choice addresses both.

Major Wheeler is the cultivar recommended most consistently, and the reasons are specific rather than general. Penn State Master Gardeners report it starting to bloom in mid May and continuing until after frost, which is a far longer season than the species usually gives, in heavy scarlet flushes. They also report never seeing a trace of mildew on it, alongside the cultivar Magnifica. It is vigorous with it: a single one-gallon plant reached ten feet tall and six feet wide within two years.

The practical consequence of that vigor is that it needs its support built before planting, and a structure sized for a mature vine rather than the plant in the pot. A twining vine cannot be moved to a bigger trellis later without cutting it back hard.

The fire risk, which is easy to miss

NC State flags trumpet honeysuckle as high flammability and advises against planting near homes.

That is an unusual note to find on an ornamental vine and it is worth taking at face value, particularly in regions with a real wildfire season. A dense flammable vine growing up a wall or across a porch is exactly the fuel path that defensible-space guidance is written to prevent.

On a freestanding arbor, fence or pergola away from the building, the concern does not apply in the same way.

What it feeds

NC State records the flowers attracting hummingbirds, bees, butterflies and some moth pollinators, with small red berries taken by songbirds.

The long red trumpet is a hummingbird flower in the textbook sense: the shape excludes most insects and the color is one hummingbirds find readily. Flowering runs from mid spring through summer, March to July, which covers the migration and the breeding season rather than a brief window.

Deer browse the foliage, which is worth knowing before planting one on a low fence in deer country.

What goes wrong

NC State’s list is short: aphids, plus powdery mildew and leaf spots, particularly in hot and humid summer climates.

Aphids on honeysuckle can be dense on the new growth in spring, and they are largely cosmetic on an established vine. Mildew and leaf spot follow humidity and still air, so a vine on an open structure has far less trouble than one flat against a wall.

The complaint that is not a disease is a vigorous plant with very few flowers, and it is nearly always shade, nitrogen, or pruning at the wrong time.

Worked through as symptoms, honeysuckle problems sort into a short list, and almost all of them are cultural.

• White dusty coating on the leaves. Powdery mildew, following humidity and still air. It is worst on a vine flat against a wall and much less trouble on an open arbor or fence where air moves through. Mildew-resistant cultivars are the durable fix.
• Curled, sticky new growth in spring. Aphids, which can be dense on this plant and are largely cosmetic on an established vine. They collapse once predators catch up, and spraying mainly delays that.
• Brown or purple spots on the leaves. Leaf spot, same conditions as the mildew, same answer.
• Plenty of leaf and almost no flower. Too much shade, too much nitrogen, or a spring prune. It flowers on new growth and is pruned after flowering, never before.
• Growth dying back from the tips on a wall-grown plant. Usually drought at the root rather than disease. The ground at the base of a wall stays dry through rain that soaks the rest of the garden.
• The vine will not climb. It twines, so it needs something narrow to wrap around. It cannot attach to a flat surface, and stems laid against a wall or a wide post simply fall away.

Does honeysuckle attract mosquitoes?

Not in the way the question usually means. Nothing about a honeysuckle vine draws mosquitoes to bite the people near it, and the scent is not a mosquito lure.

There is a real connection, but it belongs to the invasive shrub honeysuckles and their stands rather than to a vine on a trellis. Research on Culex pipiens, the main West Nile virus vector across the Northeast and Midwest, found that larvae reared on leaf litter from invasive honeysuckle produced significantly higher adult emergence than litter from most other species. The mechanism is the leaf detritus feeding the larvae in standing water, not the living plant.

The better-documented risk from the same stands is ticks rather than mosquitoes. Work at Washington University found that white-tailed deer used honeysuckle-invaded areas more heavily, that those areas carried considerably more infected ticks than adjacent uninvaded ground, and that removing the honeysuckle reduced tick-borne disease risk.

So the honest answer has two halves. A trumpet honeysuckle on an arbor is not a mosquito problem. A thicket of invasive bush honeysuckle at the back of a property is worth removing, and disease risk is one of several good reasons.

Can you grow honeysuckle indoors?

Not usefully. This is a hardy outdoor climber, and three things rule it out as a houseplant.

• Light. It grows in partial shade and it flowers in full sun. Indoor light will keep a plant alive and green and will not produce the flowers that are the whole point of it.
• Size. Ten to twenty feet of twining growth, at a rapid rate, on a support it has to wrap around.
• Dormancy. It is hardy from zone 4 and expects a cold winter. Kept warm year round it never rests properly.

The one indoor use that works is overwintering. A container-grown plant in a climate colder than its range can spend the winter in an unheated garage, shed or porch, kept cool, dark and barely watered, and go back outside in spring. That is storage rather than growing it indoors, and it is a different thing from a plant on a windowsill.

Toxicity, in plain terms

NC State’s entry carries no toxicity listing for Lonicera sempervirens, and this page records that as not recorded rather than a confident no, because an absent listing is not a positive statement of safety.

Honeysuckle berries in general are not a fruit to eat, and several Lonicera species are recorded as causing stomach upset. Songbirds take them without difficulty.

Frequently asked questions

Why does my honeysuckle not smell of anything?

Because it is probably the native one. NC State describes trumpet honeysuckle flowers as non-fragrant. The strongly scented honeysuckle is Japanese honeysuckle, which is invasive across much of the country.

Why is it all leaves and no flowers?

Three usual causes: too much shade, high nitrogen fertilizer, which NC State says produces foliage at the expense of flowers, or pruning before it blooms. It flowers on new growth, so pruning waits until after flowering.

Can it climb a wall?

Not on its own. It twines, so it needs something to wrap around: wires, a trellis, an arbor or a fence. Without support it sprawls along the ground as a groundcover.

Is honeysuckle a fire risk?

NC State rates this species high flammability and advises against planting near homes. On a freestanding arbor or fence away from the building that concern is much reduced, but it is worth respecting in wildfire regions.

Will it attract hummingbirds?

Reliably. The long red trumpet is a classic hummingbird flower, and it blooms from mid spring through summer rather than for a brief window. Bees, butterflies and some moths visit too, and songbirds take the berries.

Companion plants