Free standing planter pots with plants, are used extensively for exterior beautification throughout the world. Combinations of live plants and planters are used to great effect either as a matter of choice, or as the only practical solution to injecting some live planting into an environment. So far, little attention has been given to the thermal characteristics vis-à-vis ‘heat transfer to the roots’ which this article addresses. The technological requirements to effect some control over the thermal performance of planters is described, together with the particular benefits that flow from its application.

There are some inherent restrictions with regard to the type of planter and variety of plant that can be used, which in extreme environments can be compounded to make the selection of suitable plant/pot combinations limited.

Plants grown in planters will by the nature of the arrangement, have a limited root volume, unlike plants in the ground which will be able to spread their roots with little to no restrictions. The limited root zone must therefore provide the best conditions and environment to provide a secure anchorage for the plant in addition to the most suitable physical environment vis-à-vis water, nutrition etc.

A lesser known and understood variable is the root-ball temperature, a factor that can play a significant role in extreme ‘hot & cold’ climates. The ‘hot’ climate is looked at in the United Arab Emirates, where summer temperatures can reach 50oC in the shade.

The United Arab Emirates has some beautiful landscapes, and much time effort and money goes into their creation and maintenance. The vast predominance of exterior landscape is “in the ground”, but there are also many free standing planters and ‘built-in planters’ on display. Few plant varieties thrive in pots in the harsh summer conditions however, so the choice of plant and pot selection is severely limited.

Providing thermal protection to plant roots in planters was an idea conceived and developed by Douglas Bott at Siji Greenhouse. Experiments have been carried out over the last four years to examine the potential benefits of providing thermal lining to planters, with a view to ameliorating the deleterious effects of temperature variations in the root zone.