Creating a Tropical Oasis in a Northern Garden
Hardy Plants to Create a Tropical Looking Garden
One of the hot trends in gardening for the last couple of years has been to create a lush, Southern tropical oasis right in your own back yard. Transforming a ho-hum garden into a tropical paradise by using masses of brightly coloured blooms or attractive berries set off by a rich tapestry of foliage is possible to achieve, even in northern climates. Combining colour and selecting plants for their strong architectural value allows gardeners to create dramatic scenes in the garden giving the image of a tropical paradise from far, far away.
Creating an authentic tropical garden in a northern garden means dealing with the challenges of using plants native to an area that extends from an area bordering the equator from the Tropic of Cancer to the Tropic of Capricorn. Many of these tropical plants are happiest in an environment that has continuous year round sunshine and balmy, warm temperatures. In this area the sun shines for the same twelve hours every day, all year round. The sun in the tropics heats up the air to a nice 30 to 40 degrees Celsius (80-90 deg. F.) too. Another challenge presented by a true tropical climate are the rainy and dry seasons that result in almost daily torrential rain in the afternoon for months followed by drought that puts plants into dormancy. Recreating most of these conditions in northern gardens is almost impossible unless unlimited funds were available. So without an environment that is similar to their native home, many of what we think of as true tropicals are going to sulk, decline or outright die.
Some tropical plants though will still flourish in northern gardens. Getting these to grow well though might present an additional challenge. Finding plants that are large enough to make an impact is a difficult task since there are usually not too many 2-metre (6 feet) tall palm trees in local garden centres. What might be available is a colourful croton, say about 60 cm (2 feet) tall if lucky. Unfortunately this won’t contribute much toward the overall tropical feel in the garden until they have grown for a season or three. Searching for a large variegated ginger, that is one metre (3 feet) tall, will be a lengthy process and probably quite pricey.
Since the effort to find real tropical plants that are suitable for an outdoor garden is considerable, most gardeners will want to keep them for more than just one season. The plants really deserve to be kept over the winter instead of landing in the compost pile when temperatures start to fall to near freezing. To overwinter tropicals, the minimum requirement is a heated room to keep temperatures above freezing and the ideal is to have a bright, warm conservatory or greenhouse to re-create natural conditions.
If the efforts needed to recreate the tropical garden using authentic tropical plants are a bit daunting, there are hardy plants that can be used as tropical impostors! It is possible with a few tropical-looking temperate plants placed strategically in the garden, to change the feel of a traditional garden into one that resembles gardens seen in the Caribbean, Hawaii, Mexico or Costa Rica. There are cold-hardy plants that have a dramatic size and form, vivid foliage, and extravagant flowers that resemble their more tender counterparts. Combining these tropical-looking, yet hardy plants in a dense planting and a tropical effect can be gained without dealing with overwintering tender plants indoors through the winter. A quick visit to the garden centre will show that there are plenty of perennials, shrubs and trees that could pass as tropicals in our garden climate. Just look at them from a tropical prospective and select those that best represent the theme.
Some of the best tropical plant impostors have variegated foliage. The exotic looking 5-metre (15 foot) tall, gold-variegated Japanese angelica tree is a great candidate for a full sun or partial shade location and is very hardy. The leaves are edged in cream-yellow colour which develops a pink tone in the fall if grown in the sun.
The deep purple foliage of forest pansy Eastern redbud is similar to many tropical shrubs. The heart shaped leaves are an attractive red-purple colour in the spring. These change to dark green during the summer and return to a good purple for the fall. This shrub grows in full sun or partial shade and will reach 3 metres (9 feet) tall at maturity. An added benefit is the rose-purple pea-shape flower in the spring.
Maroon foliage is also key to the attractiveness of the ‘Royal Purple’ smoke tree. This time each leaf is round in shape and starts out a rich maroon-red colour in the spring. The colour deepens to a purplish-red or close to black in the summer. In the fall, the leaves turn a rich, red-purple colour. The flowers and seeds of the smoke tree are very different from other plants. They are full plumes containing small, airy flowers that fast develop into fluffy seedheads that last for months. The plumes are beautiful and are colour coordinated purple too. The shrub can easily be pruned to stay compact, or if left unpruned will reach 5 metres (15 feet). Full sun is essential for the best foliage colour and blooms.
For a dramatic golden foliage statement in the garden, try ‘Sum and Substance’ hosta. Incredibly hardy, this hosta has golden chartreuse leaves and pale lavender blooms in late summer. The ultimate size is 80 cm (32 inches) tall and 2 metres (6 feet) wide. Also the golden leaf locust will produce a sunny, golden glow from its leaves if a taller plant is needed.
Hardy ornamental grasses can also be used to create the impression of a tropical garden. Try the hakone grass (also called Japanese forest grass) which is know in the nursery as Hakonechloa macra ‘Aureola’ for its bold gold striped leaves that reach 40 cm. (15 inches). This plant needs partial shade to avoid scorching. Other striking, sword-like foliage combinations can be made with variegated and zebra iris.
The common rose mallow (such as the cultivars of Hibiscus moscheutos ‘Fantasia’ and ‘Plum Crazy’) are grown for their exotic, large colourful blooms from late summer to fall. Pair this mallow with an ornamental rhubarb (Rheum palmatum var. tanguticum) or the plume poppy (Macleaya cordata) for a dramatic effect.
Where there’s an idea and the will to make it happen, there’s a way to create a tropical oasis in any garden!