Worldwide, there are approximately 300 species of clematis, with many from Mediterranean climates, and winter, spring to early summer is the best time to see them in flower.
Some clematis are best grown in containers that can be placed so that roots are in the shade. In containers, suitable composts can be provided to ensure plants can obtain ample nutrients and moisture throughout the growing season.
This article will concentrate on the species and other small-flowered clematis, which are less demanding and eminently suitable for cultivating in the Algarve. Shady terraces and pergolas will show them off at their best.
Soil preparation is paramount to the successful long-term cultivation of clematis in the ground; however, we can dispense with one myth immediately. The acidity or alkalinity (ph value) of garden soil is of little relevance to most clematis. In fact, far from being “lime lovers”, they are actually “lime tolerant”. The reason C. vitalba grows so well on chalk is all about the free draining properties of chalk. Any value of ph between 5.5 and 8.5 is suitable for clematis.
Soil preparation should make the soil deep, humus rich, moisture retentive and yet free draining. It may be necessary to add considerable amounts of grit to heavy clay soils, but a well-worked, clay-based soil will support the cultivation of most types of clematis. Poor quality and sandy soils will require regular additions of nutrients, plus moisture-retaining compost, both to support good root systems and to minimise moisture evaporation, perhaps by using a mulch.
Unlike large-flowered clematis, small-flowered species and cultivars often resent being overfed. They react by putting on soft leafy growth and very few blooms.
The soft growth can easily be damaged by strong winds and if it is sunny and hot. In nature, these lovely small-flowered clematis get by happily on what few nutrients occur naturally in their habitat, together with the humus from the annual leaf fall from their host or companion plants.
Most clematis are sociable plants, happily sharing with almost any other plant that can provide means of support and/or shade and shelter. Some stunning combinations can be created with other climbing plants in the ground or in containers. Local native species C. flammula happily scrambles through and over evergreen shrubs such as Pistaccia lentiscus.
Mediterranean-type gardens are often already well stocked with native plants, so planting a young clematis amongst such plants needs careful preparation. The soil will already be criss-crossed with coarse and fine roots of the existing plants and these root systems may extend far and wide as well as to a good depth.
If the new clematis is to succeed, its immediate rooting area must receive some careful preparation. The existing plants have had thousands of years of evolution to get the best from whatever is available to their roots, whilst the clematis, certainly in its first two seasons, is not equipped to share its compost with such vigorous plants.
Ensure the base of the planting hole drains water away (clematis love water but hate standing in it), place humus rich compost and fertiliser at the base of the hole, then slide clematis from the pot into the planting hole, adding good compost. The top of the root ball can be a little below the top of the hole, but small-flowered and species clematis do not need planting as deep as large-flowered cultivars as clematis wilt does not affect them.
All clematis being grown with other plants should be set on the north side of the chosen host plant to obtain what little shade is available.
Give the clematis at least 5 litres of water and always remember that whenever you water it, give it enough to go down past the roots, to encourage growth downwards into cooler soil. Create a bowl around the plant which retains and directs water to the roots. Many newly-planted clematis fail due to being given water often but too little at a time. The roots of such clematis remain near the surface and quickly succumb when the soil temperature becomes too warm for them.
Which clematis should be tried?
Clematis flammula, C. cirrhosa and C. viticella are native to the Mediterranean and are often found growing wild. They will all be very variable in nature, so note any outstanding specimens seen in the wild (larger blooms or better scent) and then propagate by layering or by cuttings.
C. cirrhosa has given rise to many cultivars that are more endearing to gardeners than the species itself. C. ‘Freckles’ is by far the best, often blooming for five or six months, with pink bells and vivid red freckling. Also recommended is C. ‘Ourika Valley’, a greeny cream with much larger blooms than normal.
C. ‘Landesdowne Gem’ is red inside and pink outside, a wonderful colour for an evergreen clematis. All the cirrhosas are evergreen in the winter, but many of them will go completely dormant in a long hot summer, often disappearing below the undergrowth until early September when they re-emerge and in bloom again within six weeks of the first rains.
Another evergreen clematis, which blooms around the turn of the year, is C. napaulensis. Its blooms hang like cream and purple tassels. It too goes into a summer dormancy period the same as the cirrhosas.
C. viticella occurs naturally in purple, pink, blue and various other shades. The true C. viticella has a nodding bell-shaped bloom, whilst many of its cultivars and hybrids range from bells to completely flat upward-facing flowers.
If obtaining a good range of clematis plants is difficult, then why not try growing your own from seed. The International Clematis Society has a Seed Exchange scheme where seed of unusual and rare clematis are offered for sale to members and to other gardeners.
There is little in life that is more satisfying than seeing your own seedlings coming into bloom for the first time and clematis are not at all difficult to grow. Germination can be as quick as three weeks or as slow as 12 to 15 months. Some seed set in the Algarve in mid-November was up and ready to transplant in early February. Information on growing clematis from seed is available on the website below.
Whilst it is true that the large showy types first attract some gardeners to clematis, most devotees gradually include and then move over to the smaller flower types almost completely. If you attempt to use only large-flowered types in Mediterranean climates, you will miss out on some wonderful scents from the small-flowered species, which include vanilla, cinnamon, clove, lily of the valley, hyacinth, violet, cowslip, lemon and almond.
With grateful thanks to Mike Brown, ex-President, UK Clematis Society
By Rosie Peddle