The exotic survival guide
British winters can easily finish off these trendy beauties, so you need to act fast
OVER the past couple of decades, exotic plants have spiralled i n popularity. Tree ferns, bamboos, hardy bananas and a host of species from far-flung places have taken root in our gardens, where they are treasured for their architectural structure, dazzling flowers and dramatic foliage.
Despite all their advantages, there is a drawback to filling your plot with exotics – many are vulnerable to our winter weather. Frost, snow, rain and gusty blasts can really knock the stuffing out of these beauties, resulting in their exit or causing long-lasting damage to foliage, shoots and roots.
As you read this, nobody really knows what winter has in store but I would advise against leaving exotics to their own devices. Take action now to protect vulnerable specimens and they stand an excellent chance of making it through the next few months unscathed.
Some plants need very l i ttle care. The foliage of half- hardy shrubs, such as Pittosporum tobira, bottlebrushes and Melianthus major, will survive a cold snap if you protect them with horticultural fleece, while tall bamboos will remain upright during strong winds if clumps are encircled with rope and tied to a stake.
A number of palms are ultratough, able to endure temperatures as low as -10C. Chamaerops humilis, Trachycarpus fortunei and Butia capitata fall into this camp. Canary Island date palms (Phoenix canariensis) are less hardy – pile straw around the base, tie leaves together tightly and wrap the structure in fleece.
The foliage of Japanese bananas (Musa basjoo) can deal with frost down to -2C, while the trunk will survive temperatures of about -10C. However, the roots are completely hardy, so even if everything above ground dies back, the plant will still regrow from beneath ground the following spring.
It is possible to retain the height of plants with some careful cosseting. Protect a single stem by removing leaves, placing a plastic pipe over the top and packing with straw. Build a chicken-wire cage around a grove of bananas, filling the void with straw and covering with a waterproof sheet.
I’ve seen several techniques used to protect tree ferns. The most extreme involved stuffing a handful of bracken into the crown, before bending fronds inwards until they snapped. The fronds were then folded over and snapped several more times, leaving them perched on top of the trunk like a big nest. It might sound brutal but the theory is that the broken fronds will keep the crown snug, preventing damage to embryonic shoots.
To retain them for a more impressive canopy next year, simply scoop the whole lot up vertically, tie securely with string and wrap with fleece.
In mild inner cities and coastal locations, gardeners often let tree ferns take their chances. It’s not worth the risk. My garden on the South Coast is rarely troubled by frost but I still protect my tree ferns by tucking a handful of straw into the hollow at the top of the trunks.
If you live in a cold part of the country or have soil that tends to hold on to moisture, then it’s best to lift tender summer- flowering bulbs, corms and rhizomes from the ground. Allow them to dry, then store in trays of compost or sand. Keep in a frost- free place until ready to plant out in spring.
Those in mild areas with freedraining soil can leave bulbs in situ. Cut the main stems to ground level once flowers fade and tidy up tatty growth as it dies back. Cover the surface with a 3in layer of leafmould, compost or bark chippings.