Santolina pinnata (Rosemary-Leaved Lavender Cotton)
Santolina pinnata, commonly called Rosemary-leaved Lavender Cotton or Green Santolina, is a small, aromatic, evergreen shrub with a compact cushion form. It has feathery, grey-green leaves and long wiry stalks bearing pale yellow button-like flower heads.
It is a drought-tolerant shrub native to the Mediterranean basin, specifically Italy.
HEIGHT & WIDTH
- Botanical name: Santolina pinnata (san-toh-LEE-nuh pin-NAY-tuh)
- Family: Asteraceae (ass-ter-AY-see-eye)
- Common name: Rosemary-leaved Lavender Cotton, Green Santolina
- Synonym: Santolina leucantha
|Santolina||Derives from the Latin words Sanctus Linum meaning holy flax, referring to the “miraculous” healing properties of these plants.|
|pinnata||From Latin word pinna meaning a feather, referring to the feather-shaped leaf.|
How to identify Santolina pinnata
Small, aromatic evergreen shrub with a compact cushion shape. It has slender, finely divided grey-green leaves and solitary pale yellow flower heads on long stems rising above the foliage.
It has upright stems in the middle and slightly curving stems on the edges.
The shrub has an average height of 60 cm ( 1.9 ft) and a width of 60 cm (1.9 ft)
The stems are more or less straight, i.e., upright in the middle and slightly curved at the edges. They are green and hairless.
The stems have alternate, pinnate leaves, with tufts of smaller leaves at the axils.
The flower stems are long and slightly thickened at the base of the pale yellow inflorescence.
The leaf is aromatic, grey-green, hairless, and sessile or short-stalked.
The form is pinnate, with thin cylindrical segments with round ends, usually arranged in 2 or 4 rows, giving it a feathery look.
The overall shape of the leaf is linear.
The size of the main leaves varies between 2.5 and 5 cm ( 1 and 2 in) long and 0.3 to 0.6 cm (0.12 and 0.25 in) wide. The axillary leaves are smaller.
The inflorescence has a capitulum form (button-shaped) and varies between 1 to 2 cm (0.39 to 0.78 in) in diameter. It is composed only of disc florets. There are no ray florets.
The tiny pale-yellow flowers (disc florets) are tubular and have five petals fused at the base. They are held in a tight bundle enclosed by rows of involucral bracts. The stamens and pistil stick out from inside the corolla.
An interesting fact is that the Santolina flowers mature centripetally, i.e. the outer flowers are older and open earlier than the inner ones. That is why the flower button has a darker colour in the centre.
The button-like pale-yellow flowers sit on the tip of long thin stalks 7.6 to 15 cm (3 to 6 in) long and bloom in the summer.
Santolina pinnata Usage
This shrub is very pretty and is mainly grown for its foliage with a delicate feathery look. During the summer, its long flower stalks rise above the foliage carrying pale yellow button-like flowers that create a spectacular effect.
It can be used as a solitary plant or planted in groups. Can be planted in pots, beds or borders. In rock or gravel gardens.
Its compact form that can be easily trained makes it an interesting plant to be used as a hedge.
It is also very popular for seaside gardens because of its resistance to salty water sprays.
Santolina pinnata has been used in folk medicine for its anti-inflammatory, antispasmodic and anthelminthic activities. (I could not find any scientific research done on this species to confirm these properties).
Its main use is for treating cough, digestive problems and deworming.
The flowers of this shrub are attractive to bees, butterflies and other pollinating insects, which then attract other wildlife, such as birds, enhancing the biodiversity of your garden.
This santolina has been used as an insect repellent, being placed in closets and drawers to repel cloth moths.
Santolina pinnata habitat
This shrub grows in the typical Mediterranean landscape at altitudes from 500 to 1500m (1600 to 4900 ft).
It is seen in dry, rocky and sandy areas. Scrublands, thickets and forest clearings.
It also grows in coastal areas because of its tolerance to maritime exposure.
How to care for Santolina pinnata
This shrub is fully hardy, tolerating frost and temperatures down to -15ºc (5ºF) as long as the soil is well drained.
However, until it is fully established, it will need winter protection. Add some mulch to protect the roots from low temperatures and the foliage from the wet soil.
Needs full sun (at least 6 hours per day) to maintain its best colour and compact shape. It will not flourish in the shade, becoming more floppy as the stems lose their firmness when deprived of sunlight.
It likes hot, well-drained to dry, stony or sandy soils. It especially dislikes wet soil, which makes it more exposed to fungal diseases.
If prefers poor soils, if they’re fertile, the shrub tends to become leggy, produce less essential oils and has more difficulty tolerating drought and cold temperatures.
It grows well in most types of soils: mildly acidic, neutral and mildly alkaline.
Once established, Green Santolina is drought tolerant and can go for some time without water (about 4 months if the temperature is not too hot).
Overwatering will probably kill it. In particular, the combination of heat and humidity can lead to fungal disease.
During the first two years after planting, you will need to water the young Santolina every two to three weeks during the summer. Allow the soil to dry out between watering. In case of a heat wave, water more frequently. Monitor your plants closely and look out for any signs of stress.
To preserve the soil´s moisture, you should add mulch around the root area of the plant (but not too close to the base). Wood chips and gravel are good options for mulching.
Santolina pinnata can tolerate strong winds and maritime exposure, being adapted to coastal conditions.
The best season to plant is during Autumn, so it will have all winter to develop its roots. In very cold areas, it is best to plant during the spring as long as there is available water throughout the summer to survive while developing its roots.
How to prune Santolina pinnata
Green Santolina needs to be pruned a couple of times during the year to remain vigorous and compact.
Ideally, you should give it a hard prune in early spring, which is essential to maintain its compactness and avoid becoming too woody or splitting apart. Then a light prune in late summer after flowering to encourage bushiness.
Be careful to always prune above the leaf, as the stems will not regrow if it is cut back too hard.
How to propagate Santolina pinnata
The best way to propagate is by semi-hardwood cuttings taken in the summer or early autumn or by layering.
You can also propagate by sowing seeds in a cold frame in autumn or spring. There is a great article about seed propagation at NC Extension.
Other Santolinas you may also like
Sources of information used for this article
Article from the Internation Dendrology Society Trees and Shrubs online
Models for 3D images from https://identify.plantnet.org/the-plant-list/species/Santolina%20pinnata%20Viv./data