How to grow Trachelospermum
Trachelospermum is a woody, evergreen, twining climber found growing wild in woodland from India to Japan. Of the 20 or so species, two are well-suited to our UK climate; Trachelospermum jasminoides (star jasmine) and T. asiaticum (Chinese jasmine). Both are grown for their abundance of highly fragrant summer flowers (June to September) and handsome, year-round foliage. T. jasminoides is the larger and more vigorous of the two and bears pure white flowers (though yellow cultivars are available). Its leaves are longer and turn an attractive bronze-red in the cooler months. The smaller-leaved T. asiaticum has cream flowers which age to yellow, with several popular pink forms as well.
Trachelospermum is a relatively slow-growing, long-lived plant which, unlike many climbers, requires little in the way of pruning and training. Given a warm, sheltered spot and something to climb up (wires, trellis, pergola etc.), it should cover a support largely under its own steam, scrambling and twining both vertically and horizontally.
Though similar in some ways (as implied with the common names) trachelospermum is not a type of jasmine nor even related to it. Trachelospermum belongs to the Apocynaceae plant family which also includes things like periwinkle and oleander, while jasmine is in Oleaceae (the olive family).
Key Information
Soil pH
Position
Hardiness
Where & when to plant Trachelospermum
Position - A warm, sheltered spot (out of cold, drying winds) in full sun or partial shade. Against a south or west facing wall is ideal.
Soil - Fertile and well-draining. Soggy soil is best avoided. Prefers a neutral to alkaline pH, though will grow in slightly acidic soil.
Flowering Period - Summer
Hardiness - Hardy in a sheltered spot. Rated H4 (-5 to -10°C) or H5 (-10 to -15°C) depending on the species or cultivar.
For best results, plant trachelospermum in autumn or spring. An autumn planting can be done by those gardening in mild conditions (and broadly speaking, this is the southern half of the UK). For those liable to cold winters, it is best to wait until spring (generally the northern half of the UK). Try to avoid a midsummer planting, as woody plants struggle to establish well from this.
Trachelospermum enjoys a warm, sheltered spot such as against a wall or building, and does particularly well in an urban environment. If you get severe winters where you live, growing trachelospermum in a cool greenhouse or conservatory can be a good idea; its root system is relatively shallow, so it is perfectly happy to spend life in a large container. Remember it will need some form of support to climb up. A standalone wigwam or similar designed especially for containers not only looks great, but means the plant can be moved outdoors during the summer months.
To get the most out of your trachelospermum, try to locate it where its powerfully sweet scent may be best enjoyed, such as near a seating area or regularly frequented doorway.
How to plant Trachelospermum
· For planting in the garden, it is best to install the support (wires, trellis etc.) first.
· Dig the soil area removing any large stones and weeds and breaking up any lumps. Mix in some organic matter such as manure or garden compost. Rake level and firm with your heels. Rake level again.
· Water the plant well and allow to drain before planting.
· Dig a hole twice the width of the root-ball.
· Place the plant in the hole, ensuring the top of the root ball sits level with the surface of the soil. Too low and the plant may rot, too high and the roots can dry out.
· Backfill with soil and firm in gently with your foot.
· Though trachelospermum naturally twines its own way up and across a support, it is worth giving it a helping hand at this early stage with some tying in of growth. Repeat a few more time until you’re confident it can continue unaided.
· For smaller specimens which don’t yet reach the support, tie growth to an angled cane inserted into the ground to encourage growth in the right direction.
· Soak well with water.
· Mulch around the base with well-rotted organic matter.
· For planting in containers, first choose an appropriately sized pot. For slower-growing plants like this, the best practice is to start just a few centimetres larger than the rootball and increase in size every year or two (this is so they’re not sitting in wet, unused compost which may cause the roots to rot). Always ensure there are plenty of drainage holes in the bottom.
· If you are using a large or heavy pot, it can be a good idea to fill and plant it in situ to save yourself the trouble of moving once full.
· Use a loam-based compost with some horticultural grit mixed in, and, if not already present in the compost (check the description on the bag) some slow-release fertiliser granules.
· Start by partially filling the pot with compost; enough so that when placed on it the upper surface of the root ball is about 3 centimetres lower than the top of the pot.
· Infill all the space surrounding the root ball with compost, firming down with your fingers then adding a little more so the plant is held tight.
· Pick up the container and lightly tap on the potting bench or ground a few times to help further settle the compost around the plant.
· Soak well with water.
· A mulch with horticultural grit will look attractive and help to prevent a ‘cap’ or crust forming on the top of the compost (something container plants can suffer due to the artificial nature of their watering).
· Position next to a wall where there is some form of support such as wires or a trellis. Alternatively, insert a standalone support into the container.
· Though trachelospermum naturally twines its own way up and across a support, it is worth tying growth in at this stage (and a few more times until it is established) to get it going.
· For smaller specimens which don’t yet reach the support, tie growth to an angled cane inserted into the ground to encourage growth in the right direction.
What to plant with Trachelospermum
As a successful climber, you could pair your Trachelospermum jasminoides with similar climbers. With Trachelospermum’s pretty white star-shaped flowers, you can add a climber such as Clematis which will add deep purples to your trellis. Other evergreen climbing plants include sweet-smelling pink Honeysuckle and eye-catching Wisteria plants.
How to care for Trachelospermum
Pruning and Deadheading
Trachelospermum is a relatively slow-growing, self-sufficient plant which rarely needs pruning. At most, you may need to tie in the odd wayward shoot, but other than that it can be left to its own devices. If you need to trim your trachelospermum to fit a designated space, do so in spring.
Neglected, overgrown specimens respond well to a hard, renovative prune, again in spring. Simply thin out any weak, dead, diseased, or damaged growth, then shorten the remaining shoots back by around two thirds, cutting to just above a healthy sideshoot.
Watering
Like all woody plants, regular watering during the first couple of growing seasons in the ground is advisable to help trachelospermum to establish a strong, healthy root system. After this it should be largely self-sufficient, particularly with the moisture-retaining help of an annual mulch (see below).
Container-grown trachelospermum can be watered freely during the growing season and sparingly during winter (i.e., just enough to prevent the compost drying out completely).
Feeding
On healthy, fertile soil, an annual mulch of well-rotted organic matter should provide sufficient nutrients for your trachelospermum. This has the added benefit of suppressing weeds and locking in moisture. Autumn is a good time to carry out mulching as this will also help insulate the roots from frost damage. It can also be carried out in spring.
For an extra boost (most likely to be needed during the first few years of the plant being in the ground, immediately after a hard renovation prune, or annually if growing in poor soil), apply a general-purpose granular feed such as blood, fish, and bone to the surface of the soil and lightly work it in. This is known as a ‘top dress’ and is best done in late winter or early spring, and again in midsummer if necessary.
Container-grown plants rely more on the gardener for nutrition. Get off to a flying start by making sure you use a good quality, loam-based compost specifically for mature plants (John Innes No. 3 is ideal), then throughout the growing season (March to September) apply a liquid feed once a month. Remember also to repot into a slightly larger pot using fresh compost every year or two. In the intervening years and once this is no longer feasible, carry out an annual topdress in spring. Scrape away the top 5cm of compost and replace with fresh, mixing in a little general-purpose slow-release feed.
Cold Protection
Unless your winters are severe, trachelospermum should survive outside without the need for additional protection (as long as it is grown in a sheltered spot out of cold, drying winds). Even so, it can be worth applying an insulating, thick winter mulch around the roots, and being prepared to cover top growth with a layer of horticultural fleece or old bedsheet in the event of a very hard frost.
For those gardening in regions where winters can be very cold and harsh, we recommend growing trachelospermum in a container to allow for overwintering in a cool yet frost-free environment. This might be a conservatory, porch, or unheated greenhouse.
Pests and Diseases
Outdoors, trachelospermum tends to be problem free. Inside, the usual issues of spider mite and aphid can crop up. Keeping plants as healthy as possible is the key to warding off problems, and by this we mean proper ventilation, adequately spaced plants (for good air flow), keeping everything well-watered and fed, and repotting into larger containers when necessary. Thoroughly cleaning the indoor environment every winter can also help to remove overwintering populations of pests.
Where infestations do take hold, try introducing biological controls (often sachets or tubes containing miniscule natural predators), or in the worst cases, remove the affected plant/s altogether.
How to propagate Trachelospermum
We find the best way to propagate trachelospermum is by taking semi-ripe cuttings from summer to autumn:
· Look for current year’s growth which is firm and woody at the base while still flexible at the tip. You’re aiming for a cutting of 10 centimetres or less (any longer and they are more likely to dry out and fail). For best results, choose stems where the leaf nodes are close together rather than far apart.
· Using a sharp knife or secateurs, sever the cutting from the plant and put in a plastic bag straight away to keep it from drying out.
· Fill a pot (or several, if you have a lot of cuttings) with a perlite-heavy compost mix (at least 50% perlite).
· Trim the end of the cutting to just below a node (point at which leaves grow).
· Remove lowest leaves, leaving 2-4 on the cutting.
· If the remaining leaves are large, cut them in half with a sharp knife (to reduce water lost through transpiration).
· Insert the cuttings into the compost and water lightly. Several cuttings can be put in the same container if there is enough space to do this without them touching.
· Place in a greenhouse or propagating unit if you have one or covered with a plastic bag on a windowsill if not (out of direct sunlight).
· Keep the cuttings misted and occasionally watered until they root. You will know this has happened when roots emerge out of the bottom of the container.
· Gently remove rooted cuttings and pot them into individual pots. Grow on in a cool yet frost-free environment such as an unheated conservatory, greenhouse, or cold frame, until they are large enough to be planted out as above.
* Many plants carry Plant Breeders Rights and cannot be propagated for commercial purposes.
Common Trachelospermum questions
· How quickly does trachelospermum grow?
Trachelospermum has a relatively slow-growth rate and can be expected to take between five and ten years to reach full size.
· Does trachelospermum need a trellis?
Yes, trachelospermum is twining rather than self-clinging (i.e., a plant which naturally adheres to a surface using aerial roots or sticky pads), meaning it requires some form of support to scramble up.
· How do you get star jasmine to climb?
New plants can be helped along with some initial tying into the support. Once established, they should continue to climb unaided.
· How do I get my star jasmine to bloom?
Lacklustre flowering may be a result of insufficient sunlight (trachelospermum will grow in shade but this results in fewer flowers), or it may be a lack of nutrients. See our ‘Feeding’ advice above for how best to boost soil fertility.
· Does trachelospermum bear fruit?
In its natural habitat, yes. However, fruiting is rare in a UK climate.
