TREES AND SHRUBS FOR WARM PLACES

This is a book designed for anyone who wants to extend their plant knowledge. It is designed as a guide for growing plants in any type of warm place; from tropical and sub tropical climates, to greenhouses and courtyards that have become heat traps in temperate places. 

The plants covered are largely “trees and shrubs”; but also include some plants that might only be described loosely as “tree like” or “shrub like”. These are included because they are plants that could be used in the landscape as a substitute for a tree or shrub. 

My intention is not to be comprehensive (as that would require a much larger book); but to provide a valuable reference or learning tool for both amateurs and professionals who work with amenity plants in locations where heat can be a limiting factor. 

This book has been a long time in development. It was first conceived in 1996 and a contract was signed with Hyland House Publishers (in Australia). The initial book was then written, and delivered to the publishers in 1997; but sadly the owners of Hyland House suffered ill health, the publisher was sold and downsized, and the manuscript was placed in a long queue of other books waiting publication. In due course, the rights were surrendered by the publisher, and the manuscript then sat waiting action. 

Over the intervening years, I have been busy both in writing and education. My core business (ACS Distance Education) has expanded into the UK, and established partnerships with 15 other colleges around the world. I have produced a dozen more books (for Kangaroo Press and others) and for three years, produced a Landscape and Gardening magazine for Sydney publisher; Express Publications. 

Throughout this time I continued to take photos of plants, everywhere from garden shows in the UK to the islands of Vanuatu and parts of South East Asia.

HINTS FOR DRY SANDY SOILS 

A useful hint for planting in dry sandy areas is to dig the hole two or three times larger than the pot size that you have to plant. It is best to dig out half of the soil onto one side of the hole and one half onto the other. This gives you two piles of the sand from the hole; to one pile add well rotted compost, peatmoss, well rotted animal manure or some loam. Mix all these together, pop some down the hole to bring it to the correct level then place your plant into the hole and backfill with the remaining soil. Gently tamp down the area around the plant to exclude and air pockets around the roots – using your hands (preferably), rather than stomping it down with your feet, as this will compact the soil too much! Any left over soil can be used to form a lip around the plant to create a small basin to retain water then water the plant in. The idea with this system is to give the plants a good growing environment but at the same time allow them to become accustomed to the soil in which they are expected to grow in. If your soil is hydrophobic though, and repels rather than absorbs water, you will need to use a wetting agent to first remedy this and then proceed as above. You may need to do this regularly though.

Many gardeners also incorporate moisture holding additives into the garden to give their plants a fighting start. Some of these products hold water in crystal form - so that it is still available to the plants. These products only last from a few months to about one year. They are short term remedies only, but do help to get the plants established.

HUMID TROPICS

When planning for the humid tropical gardens, issues such as water availability, while still important, are not as crucial as they might be for drier areas. Humid tropic species have similar water requirements to most other plant species. They, as do most species, require the most attention and watering when they are young and more susceptible to drying out due to their size. Once established however, they will survive quite happily on the natural rainfall that they receive. In fact rainforest plants are no more difficult to grow as a group than any other group of plants. While there are individual species that ARE difficult to propagate or grow, the same is true of the entire plant kingdom and rainforest species should not be shied away from because of this.

Timing and quantity of rainfall needs to be noted or recorded. It is important to know when heavy rain periods are due and the quantity expected to fall. Adequate drainage should be considered in wet seasons to remove excess rainfall to prevent damage to the site and gardens.

The dry season may demand supplementary irrigations for young plants or new gardens.

Humidity, combined with the temperature, tends to encourage fast healthy growth on most species from warm climates. It also tends to encourage various diseases. Plants from tropical climates tend to have a natural resistance to most fungal diseases. Plants from cool climates planted in tropical gardens will usually succumb to most diseases due to its unsuitability.

One of the biggest causes for plant death in the tropics is the result of gardeners attempting to grow unsuitable plants in the garden. Plants that have silvery, hairy foliage are usually poor plant selections for this climate zone. Plants with glossy waxy leaves are good selections. Just like all things in nature there are exceptions to the rules so it is wise to refer to books like this or seek advice from local professionals.

The location of the site on a hill can dramatically influence rainfall and temperature even if the hill is in the middle of a tropical district. Rain may tend to come from only one direction, consequently, the property may be on the "dry" side or "wet" side. Whether it faces north or south will also influence temperature on the site.

High altitude districts within tropical areas will have much cooler temperatures than those properties sited near the coastline.

Handy hints to assist tropical gardeners include:

·       Keep fertiliser up to plants due to extended growing/flowering periods.

·       Mulch the soil and encourage ground covers to prevent soil damage during the wet season and to conserve water in the dry season.

·       Regular pruning/trimming may be required to keep plants under control and neat.

·       Select plants that prefer the climate - disregard plants that do not cope well with humidity.

COASTAL AREAS

Coastal districts have their own share of gardening problems. The climate tends to be slightly warmer in winter and cooler in summer than areas a little inland due to shore breezes. Plants therefore placed in a protected site away from costal winds tend to grow fast and healthy.

Plants exposed to coastal winds may be subjected to salt spray. This is regarded as the biggest problem for coastal gardeners. The selection of plants must therefore suit the general climate, tolerate coastal winds, withstand salt deposits on leaves and the ground, plus survive on usually sand, low fertility soils that do not hold a lot of moisture.

The range of suitable plants is generally those which come from similar environmental districts or those which exhibit:

·       Hairy foliage;

·       Silver or grey foliage;

·       Compact habit;

·       Fine foliage.

The further you move away from the seashore, the less effect the salt-laden breezes have on plants. In one garden it is possible to have sensitive ferns on the protected side of the house, and have she-oaks (Casuarina), coastal rosemary (Westringia) and New Zealand Christmas bush (Metrosideros) on the other side that is exposed to the sea.

WINDY AREAS

Wind can cause severe damage to trees and shrubs. In storms falling plants can result in damage to buildings and other structures. In warm climates strong winds come from storms; tropical climates are prone to cyclones and hurricanes close to the sea. Plants have however adapted to these climatic forces. Palms native to most islands do not fall over or get seriously damaged by strong winds or storms. Likewise many other plants are adapted to the climatic disturbances that occur naturally.