Mountain clematis vs Trumpet vine

Mountain clematis and Trumpet vine are often considered for the same spot in the garden (flowers, screening, pollinator friendly). The data below shows where they differ: size, hardiness, care, toxicity and price.

Mountain clematis

Clematis montana 8 m × 4 m after 10 years

One of the most vigorous clematis: it climbs by twisting leaf stalks, so it needs wires, a trellis, a fence or an old tree, and will not go up a…

Climber

Full sun

Part shade

from about PLN 20

Trumpet vine

Campsis radicans 7 m × 3 m after 10 years

A very vigorous deciduous climber that clings to walls, fences and tree trunks with aerial roots and carries clusters of orange-red trumpet flowers…

Climber

Full sun

Part shade

from about PLN 27

Key differences

Mountain clematis grows larger: 8 m × 4 m after ten years, against 7 m × 3 m for Trumpet vine (an estimate: sources differ).
Trumpet vine is hardier: down to -29 °C, against -18 °C for Mountain clematis.
Trumpet vine copes better with summer heat than Mountain clematis.
Trumpet vine tolerates drought better than Mountain clematis.
Mountain clematis needs less care than Trumpet vine.

Which one to choose?

Mountain clematis is the better choice if you have little time for care.

Trumpet vine is the better choice if space is tight, the garden is cold or a frost pocket, the spot is hot and sunny or you cannot water regularly.

Watch out for

Mountain clematis

It is less hardy than other garden clematis: in Central Europe hard, windy winters can kill it back, and a late spring frost can destroy the developed flower buds, leaving it without flowers that year. Plant it by a sheltered wall and mulch the base. Pruning in winter or spring removes the flower buds. It grows very large and quickly overruns and weighs down small trellises, gutters and roof tiles. Clematis wilt, aphids, snails and earwigs can occur.

Trumpet vine

It sends up plenty of suckers from its roots, even several metres from the parent plant, in lawns, beds and paving joints, and it also seeds itself from winged seeds; a neglected plant forms an impenetrable thicket. Plant it where you can mow around it or where paving contains it. The aerial roots grip render and mortar joints, so pulling them off damages render and paint, and the heavy woody stems can lift roof tiles and grow under eaves and into gutters, so keep it well away from the roof on a house wall. Because it flowers on the current year's shoots you can cut it back hard in early spring. Young shoots may be killed back in a hard winter, but the plant resprouts. Aphids can settle on it.

The data side by side

Feature	Mountain clematis	Trumpet vine
Group	Climber	Climber
Size after 10 years	8 m × 4 m (uncertain)	7 m × 3 m (uncertain)
Ultimate size	5–12 m × 2.4–4.5 m	7.6–12 m × 1.5–4 m
Growth rate	Fast	Fast
Light	Full sun, Part shade	Full sun, Part shade
Soil	Average garden soil, Clay, Sandy, Calcareous	Average garden soil, Clay, Sandy, Calcareous, Acidic
Hardiness	down to -18 °C (USDA 6, RHS H6)	down to -29 °C (USDA 4, RHS H7)
Heat tolerance	Medium	High
Foliage	Deciduous	Deciduous
Flowering	May–June, white, pink	June–September, orange, red
Water need	Medium	Medium
Drought tolerance	Low	High
Maintenance	Low	High
Planting distance	200 cm	250 cm
For dogs	Toxic	no data
For cats	Toxic	no data
For children	Toxic	Mildly toxic
Typical price	approx. PLN 20	approx. PLN 27

Prices are rounded, indicative values. Toxicity data is for information only. If your pet or child has eaten a plant, contact a vet or a doctor. Data updated: October 17, 2026

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